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 https://archive.org/details/mortarsplasterssOOhodg_0 
 
PREFACE 
 
 Id introducing" this book to American Builders and 
 others who are interested in the use of plasters, stuccos, 
 cements and mortar, I feel that I am doing them a 
 service, as there is no such work, so far as I have been 
 able to discover, published in this country that appeals 
 so directly to the practical workman as the present vol- 
 ume does; as I have endeavored to put together as much 
 practical stuff as it was possible to wedge in in a vol- 
 ume of this size, and in order to do this, I have gleaned 
 the best things I could find in English, American and 
 other books and journals, to which I have added much 
 drawn from my own experience, and from the experi- 
 ences of many practical workmen. I have particularly 
 drawn at length from Miller's exhaustive work on the 
 subject of plastering and stucco work, and am also 
 indebted to the same source for a number of illustra- 
 tions used in PART ONE. I have also drawn from 
 Robert Scott Burns to some small extent, and from an 
 earlier work of my own, and from articles I have fur- 
 nished to various building journals during the last 
 thirty years. Part Two is made up partly from my 
 own experience, and partly from treatises on cements 
 and concretes, and from Government Bulletins pub- 
 lished in Washington, D. C. The paragraphs and illus- 
 trations on reinforced concrete are mostly taken from 
 reports of scientific societies, and from papers read 
 before conventions, and from letters and descriptions 
 prepared by manufacturers and users of Portland ce= 
 
 5 
 
 188^8 
 
6 
 
 CEMENTS AND CONCRETES 
 
 ment, furnished me on application, and from materials 
 gathered from many sources, and, while I have added 
 considerable from my own knowledge of the sabject, 
 it may be said that the work is almost a compilation 
 taken from the best authorities on the subjects dis- 
 cussed. 
 
 There is enough material on the subject of concrete 
 floating about in the technical press, of the best kind, 
 to build up three or four volumes of the size of this 
 one, but, in analyzing it, I have sifted it down to the 
 limits of this book, preserving that, which in my judg- 
 ment, was best for the practical worker, and leaving out 
 the most of that which might be termed theoretical and, 
 therefore, to a large extent unfit for artisans' purposes. 
 In making the selections in matters of this kind, the 
 personal factor must necessarily be of more or less 
 value, and I flatter myself that, after a successful build- 
 ing experience in various forms, covering a period of 
 over fifty years, my knowledge of the value of any 
 problem pertaining to the building trades is deserving 
 of considerable respect. It is this knowledge, along 
 with some knowledge of cause and effect, and my simple 
 and unvarnished methods of placing building matters 
 before the American workmen, that have made my 
 books so popular, and lured the working public into pur- 
 chasing, at this writing, nearly two millions of them. 
 And I have reason to 'hope that this volume will, like 
 all my previous ones, meet with a reasonable amount 
 of appreciation from those who work, or guide the work 
 of others, in cements, plasters, concretes and stuccos. 
 
 Fred T. Hodgson. 
 
PART I 
 
 CONCRETES, CEMENTS, PLASTERS AND STUC- 
 COS— THEIR USES AND METHODS 
 OF WORKING SAME. 
 
 INTRODUCTORY 
 
 This book, or rather compilation, is largely made up 
 of the very best material available on the subjects it 
 proposes to discuss. All the latest improvements and 
 methods in the mixing, proportioning and application 
 of plaster, mortar, stucco and cement will be described 
 and laid before the reader in as simple and plain a man- 
 ner as possible. 
 
 The art of using mortars in some shape or other, is 
 as old as civilization, as we find evidences of its use in 
 ruins that date long before historical times, not only 
 in the older countries of Asia and Europe, but also in 
 the ruins of Mexico, Central America and Peru; and 
 the workmen who did their part, or most of this work, 
 were evidently experts at the trade, for some of the 
 remains of their work which have come down to us 
 certainly show that the work was done by men who 
 not only had a knowledge of their trade, but that they 
 also possessed a fair knowledge of the peculiar qualities 
 of the materials they used. '^Plastering," says Miller 
 in his great work on Mortars, "is one of the earliest 
 instances of man's power of inductive reasoning, for 
 when men built they plastered: at first, like the birds 
 and the beavers, with mud; but they soon found out a 
 more lasting and more comfortable method, and the 
 
 7 
 
8 
 
 CEMENTS AND CONCRETES 
 
 earliest efforts of civilization were directed to plaster- 
 ing. The inquiry into it takes us back to the dawn of 
 social life until its origin becoraes mythic and prehis- 
 toric. In that dim, obscure period Ave cannot pene- 
 trate far enough to see clearly, but the most distant 
 glimpses we can obtain into it show us that man had 
 very early attained almost to perfection in compound- 
 ing material for plastering. In fact, so far as we yet 
 know, some of the earliest plastering which has re- 
 mained to us excels, in its scientific composition, that 
 which we use at the present day, telling of ages of ex- 
 perimental attempts. The pyramids of Egypt contain 
 plaster work executed at least four thousand years ago 
 (some antiquaries, indeed, say a much longer period), 
 and this, where wilful violence has not disturbed it, 
 still exists in perfection, outvying in durability the 
 very rock it covers, where this is not protected by its 
 shield of plaster. Dr. Flinders Petrie, in his ^Pyra- 
 mids and Temples of Gizeh,' shows us how service- 
 able and intelligent a co-operator with the painter, the 
 sculptor, and the architect, was the plasterer of those 
 early days, and that to his care and skill we owe almost 
 all we know of the history of these distant times and 
 their art. Indeed the plasterer's very tools do yet re- 
 main to us, showing that the technical processes then 
 Vv^ere the same we now use, for there are in Dr. Petrie 's 
 collection hand floats which in design, shape and pur- 
 pose are precisely those which" we use today. Even our 
 newest invention of canvas plaster was well known 
 then, and by it were made the masks which yet pre- 
 serve on the mummy cases the lineaments of their occu- 
 pants. ' ' 
 
 The plaster used by the Egyptians for their finest 
 work was derived from burnt gypsum^ and was there- 
 
INTRODUCTORY 
 
 9 
 
 fore exactly the same as our ''plaster of paris.'' Its 
 base was of lime stucco, which, when used on partitions, 
 was laid in reeds, laced together with cords, for lath- 
 ing, and Mr. Miller, who has examined a fragment in 
 Dr. Petrie's collection, finds it practically ''three coat 
 work," about % of an inch thick, haired and finished 
 just as we do now. 
 
 Plaster moulds and cast slabs exist, but there does not 
 appear any evidence of piece moulding, nor does any 
 evidence of the use of modelled work in plaster exist. 
 That some process of indurating plaster was thus early 
 known is evidenced by the plaster pavement at Tel-el 
 Amarna, which is elaborately painted. The floor of 
 this work is laid on brick; the first coat is of rough 
 lime stucco about 1 inch thick, and the finishing coat 
 of well-haired plaster about % inch thick, very smooth 
 and fine, and showing evidence of trowelling, the set- 
 ting out lines for the painting being formed by a struck 
 cord before the surface was set, and the painting done 
 on fresco. It is about 60 by 20, and formed the floor 
 of the principal room of the harem of King Amenhotop 
 IV., about fourteen hundred years before Christ, that 
 is, between three thousand and four thousand years 
 ago. Long before this, plastering of fine quality 
 existed in Egypt, and so long as its civilization con- 
 tinued it aided the comfort of the dwellings of its 
 people and the beauty of its temples. 
 
 Nor was it merely for its beauty and comfort that 
 plaster work was used. Even then its sanitary value 
 was recognized, and the directions given in Leviticus 
 xiv, 42-48, which was probably written about one hun- 
 dred years before this date, show that the knowledge 
 of its antiseptic qualities was widely spread^ and the 
 practice of it regarded as religious duty. 
 
10 CEMENTS AND CONCRETES 
 
 Unfortunately there is no direct evidence that the 
 adjacent Assyrian powers of Nineveh and Babylon nsed 
 plaster work. Possibly the fine clay brought down by the 
 rivers of the Euphrates and the Tigris sufficed for all 
 their purposes. Their records are in it : their illustra- 
 tions on the sculptured walls of their palaces are in 
 stone, their painting is glazed on their bricks, and for 
 them there seems to have been but little need for plas- 
 ter work, nor do we find until the rise of Grecian art 
 anything relating to our subject. 
 
 Very early in Greek architecture we find the use of 
 plaster, and in this case a true lime stucco of most ex- 
 quisite composition, thin, fine and white. Some has 
 been found at Mycenae, a city of Homeric date. We 
 know that it existed in perfection in Greece about five 
 hundred years before the Christian era. With this the 
 temples were covered externally, and internally where 
 they were not built of marble, and in some cases where 
 they were. This fine stucco was often used as a ground 
 on which to paint their decorative ornament, but not 
 infrequently left quite plain in its larger masses, and 
 some of it remains in very fair preservation even to 
 this day. The Temple of Apollo at Bassae, built of 
 yellow sandstone about 470 B. C, has on its columns 
 the remains of a fine white stucco. 
 
 Pavements of thick, hard plaster, stained, of various 
 colors, were common in the Greek temples. One of 
 these, that of the Temple of Jupiter Panhellenius at 
 ^gina, built about 570 B. C, is described by Cockerell 
 as existing in the early part of the century, in good 
 condition, though the temple itself was destroyed ; and 
 I have seen at Agrigentum plaster existing in perfect 
 state, though scarcely thicker than an egg-shell, on the 
 sheltered parts of a temple built at least three hundred 
 
INTRODUCTORY 
 
 11 
 
 /ears before our era, whilst the unprotected stone was 
 weather worn and decayed. 
 
 What care the ancient Greeks bestowed on their 
 stucco may be inferred from Pliny's statement that in 
 the temple at El:s about 450 B. Panaenus, the 
 nephew of Phidias, used for the groundwork of his 
 picture stucco mixed with milk and saffron, and pol- 
 ished with spittle rubbed on by the ball of the thumb, 
 and," says he^ ^'it still retains the odor of saffron/' 
 Lysippus, the first of the Greek '^realists" in sculpture, 
 was the first we hear of who took casts of the faces of 
 living sitters about 300 B. C, so the art of plaster cast- 
 ing must have advanced a good deal by that time, as he 
 made presents of copies to his friends. Afterwards we 
 read of many sculptors who sent smaller plaster models 
 of their works to friends. These were, however, prob- 
 ably carved in the plaster rather than cast. 
 
 Whether the Greeks used stucco for modelling is a 
 somewhat doubtful point amongst antiquarians. From 
 certain passages in classic writers I am induced to think 
 they did. Pausanius, who describes the temple at Stym- 
 phalus, an almost deserted and ruined city when he 
 visited it about 130 A. D., describes the ceiling of the 
 Temple of the Stymphalides, built about 400 B. C, as 
 being either of stucco or carved wood," he could not 
 decide which, but his very doubt would imply that 
 stucco or wood were equally common. Now, this ceil- 
 ing was ornamented with panels and figures of the 
 harpies — omens of evil, half woman and half bird, with 
 outspread wings. He also mentions a statue of Bac- 
 chus in '^colored stucco." Of course these are not defi- 
 nite proofs of early Greek stucco modelling, but as the 
 city of Stymphalus had decayed and become depopu- 
 lated before 200 B. C, there is certainly presumptive 
 
12 
 
 CEMENTS AND CONCRETES 
 
 evidence of the ancient practice of the art. Again, fig- 
 ures of unburnt earth are mentioned in contradistinc- 
 tion to those of terra cotta, and sundry other allusions 
 to plastic work occur, which lead me to the opinion that 
 quite early in Greek art this mode of using plaster be- 
 gan. At any rate, we know that it was early introduced 
 into Grecia Magna — the earliest Southern Italian col- 
 ony of the Greeks; and as colonists invariably preserve 
 the customs and traditions of their fatherland even long 
 after they have fallen into disuse in their native hom.e, 
 we can have no reasonable doubt but this art was im- 
 ported rather than invented by them. Thence it spread 
 to the Etruscans of Middle Italy, a cognate people to 
 the Southern Greeks, by whom both plain and modelled 
 stucco was largely used. The Etruscans, as we have 
 seen, were more closely allied to the Greek than the 
 Latin race, but in the course of time these two races 
 amalgamated, the former bringing skill in handicraft, 
 the latter lust of power, and patriotic love of country 
 and of glory, whilst the Grecian element, which blended 
 harmoniously with the first of these, added a love of art. 
 
 This union, however, took long to ripen to artistic 
 fruitfulness. The practical Etruscan element firstly 
 constructed the roads and the sewers, and gave health to 
 Rome. The Latins added to their territory until it em- 
 braced half of Europe, giving wealth to Rome, and not 
 till the luxury and comfort thus created did the artis- 
 tic element of the Greek come in, giving beauty to 
 Rome, and the day of decorative plaster work ap- 
 proached its noontide glory, making Rome the attrac- 
 tion of the world. The absorbance of Greece as a 
 Roman province took place B. C. 145, and the loot of 
 it began, giving an enormous impetus to Roman art. 
 Thousands of statues were brought to Rome, and to 
 
INTRODUCTORY 
 
 be deemed a connoisseur in things artistic or a patron 
 of the arts became the fashionable ambition. But it 
 was not until the century just preceding the Christian 
 era that it became especially noteworthy. Of course 
 there is hardly anything left to us of the very early 
 plaster w^ork of Rome. The constant search for some 
 new thing was inimical to the old. Old structures were 
 pulled down to make way for new, which in their turn 
 gave way to newer, and until the age of Augustus we 
 have but little of the early work left. Strabo, who 
 visited Rome about this time, complains of the destruc- 
 tion caused by the numerous fires, and continued pull- 
 ing down of houses rendered necessary, for even pulL 
 ing down and rebuilding in order to gratify the taste 
 is but voluntary ruin; and Augustus, who boasted that 
 *'he found Rome of brick and left it of marble," in 
 replacing the brick with marble destroyed the plaster 
 work. How that plaster work was wrought we shall 
 learn more from Vitruvius, who wrote his book on archi- 
 tecture about 16 B. C, and dedicated it to the emperor, 
 ^'in order to explain the rules and limits of art as a 
 standard by which to test the merits of the buildings 
 he had erected or might erect." 
 
 Now, Vitruvius was a man who had travelled and 
 seen much. He was with Julius Caesar as a military 
 engineer in his African campaign in 46 B. C, or ten 
 years after Caesar's invasion of Britain. Afterwards 
 he became a designer of military engines, what we 
 should caJl head of the Ordnance Department, and also 
 a civil engineer, persuading him^self that he had a 
 pretty taste in architecture, just as though he were an 
 R. E. of today. Thus he had a practical and also an 
 artistic training, and here is what he says on matters 
 connected with plaster work in Book VII, Chapter IL 
 
14 
 
 CEMENTS AND CONCRETES 
 
 On tempering lime for stucco : ^ ^ This requires that the 
 lime should be of the best quality, and tempered a long 
 time before it is wanted for use; so that if any of it be 
 not burnt enough, the length of time employed in slak- 
 ing it may bring the whole mass to the same consist- 
 ency." He then advises it to be chopped with iron 
 hatchets, adding that ''if the iron exhibits a glutinous 
 substance adhering to it, it indicates the richness of the 
 lime, and the thorough slaking of it.'' For cradling 
 out, and for ceiling joists, he recommends ''the wood 
 to be of cypress, olive, heart of oak, box and juniper," as 
 neither is liable to "rot or shrink." For lathing he speci- 
 fies "Greek reeds bruised and tied with cords made from 
 Spanish broom," or if these are not procurable "marsh 
 reeds tied with cords." On these a coat of lime and 
 sand is laid, and an additional coat of sand is laid on 
 to it. As it sets it is then polished with chalk or marble. 
 This for ceilings. For plaster on wall he says : " The 
 first coat on the walls is to be laid on as roughly as 
 possible, and while drying, the sand and coat spread 
 thereon. When this work has dried, a second and a 
 third coat is laid on. The sounder the sand and coat is, 
 the more durable the work will be. The coat of marble 
 dust then follows, and this is to be so prepared that 
 when used it does not stick to the trowel. Whilst the 
 stucco is drying, another thin coat is to be laid on : this 
 is to be well worked and rubbed, then still another, 
 finer than the last. Thus with three coats and the 
 same number of marble dust coats the walls will be 
 solid, and not liable to crack. The wall that is well 
 covered with plaster and stucco, when well polished, 
 not only shines, but reflects to the spectators the images 
 falling on it. The plasterers of the Greeks not only 
 make their stucco work hard by adhering to these direc- 
 
INTRODUCTORY 
 
 15 
 
 tions, but when the plaster is mixed, cause it to be beat- 
 en with wooden staves by a great number of men, and 
 use it after this preparation. Hence some persons cut- 
 ting slabs of plaster from ancient walls use them for 
 tables and mirrors/' (Chapter III.) 
 
 You will see by these remarks the great care taken 
 through every process, and how guarded the watchful- 
 ness over the selection of materials, and you will also 
 note the retrospectiveness of Vitruvius' observation, 
 how he felt that the work done before the frantic haste 
 of his own time was the better: very much as we find 
 now. Time is an ingredient in all good work, and its 
 substitute difficult to find. 
 
 There are other tips'' contained in this work which 
 are worth extraction, as, for instance, his instructions 
 as how to plaster damp walls. In such case he prima- 
 rily suggests a cavity wall, with ventilation to insure 
 a thorough draught, and then plastering it with pot- 
 sherd mortar, ' ' or carefully covering the rough plaster 
 with pitch, which is then to be ^^lime whited over," to 
 insure ^'the second coat of pounded potsherds adhering 
 to it," when it may be finished as already described. 
 Further, he refers to modelled plaster work which, he 
 says, ought to be used with a regard to propriety," 
 and gives certain hints for its appropriate use. Speak- 
 ing of pavements ^^used in the Grecian winter rooms, 
 which are not only economical but useful," he advises 
 ''the earth to be excavated about two feet, and a foun- 
 dation of potsherd well rammed in," and then a ^^com- 
 position of pounded coal lime, sand and ashes is mixed 
 up and spread thereover, half foot in thickness, per- 
 fectly smooth and level. The surface then being rubbed 
 with stone, it has the appearance of a black surface," 
 ^'and the people, though barefoot, do not suffer from 
 
16 
 
 CEMENTS AND CONCRETES 
 
 cold on this sort of pavement.'' Now all this bespeaks 
 not only theoretical knowledge, but practical observa- 
 tion and experience, and was written nearly two thou- 
 sand years ago, from which you can surmise how far 
 advanced practical plastering had then become. This 
 written evidence is almost all we have of the work of 
 Vitruvius' own time, for even of the time of Augustus 
 hardly anything remains to us, as the great fire of 
 Nero utterly destroyed the greater part of the city in 
 the year A. D. 64, and almost the only authenticated 
 piece of plaster work done before or during his reign 
 is the Tabula Iliaca, a bas-relief of the Siege of Troy, 
 still preserved in the Capitol Museum at Rome. That 
 this was modelled by Greek artists is proved by the fact 
 that its inscriptions are all in the Greek language, and 
 by some it is considered to be of ver}^ much greater an- 
 tiquity. So much for the ancient history of the art 
 of plastering, and I trust I will be pardoned if I con- 
 tinue this sketch, bringing it down to a more recent 
 period and show in what high respect the plasterers ' art 
 was held in the Sixteenth Century, and later. Quoting 
 from an old work, giving an account of the institution 
 of ' ' The Worshipful Company of Plaisterers, ' ' and mak- 
 ing use of the quaint language then in use we are told 
 that: ^^The Plaisterers' Company, which ranks as 
 forty-sixth among the eighty-nine companies, was in- 
 corporated by King Henry VII., on March 10, 1501, to 
 search, and try, and make, and exercise due search as 
 well in, upon, and of all manner of stuff touching and 
 concerning the Art and Mystery of Pargettors, com- 
 monly called Plaisterers, and upon all work and work- 
 men in the said art or mystery, so that the said work 
 might be just, true, and lawful, without any deceit or 
 fraud whatsoever against the City of London or suburbs 
 
INTRODUCTORY 
 
 17 
 
 thereof. The Charter gave power to establish the Corn- 
 pany as the Guild or Fraternity in honour of the 
 Blessed Virgin Mary, of men of the Mystery or Art of 
 Pargettors in the City of London, commonly called 
 Plaisterers, to be increased and augmented when neces- 
 sary, and to be governed by a Master and two War- 
 dens, to be elected annually. The Master and Wardens 
 and brotherhood were to be a Hody corporate, with per- 
 petual succession and a common seal, and they were 
 empowered to purchase and enjoy in fee and perpet- 
 uity lands and other possessions in the City, suburbs 
 and elsewhere. And the charter empowered the said 
 Master and Wardens to sue and be sued as ''The Mas- 
 ter and Wardens of the Guild or Fraternity of the 
 Blessed Mary of Pargettors, commonly called Plaister- 
 ers, London.'' 
 
 THE OLD COAT OF AILJIS. 
 
 The Company under the powers to make examina- 
 tions, appears to have inflicted fines on offending par- 
 ties for using bad materials, and for bad vvorkmanship. 
 Search days appear to have been annually appointed 
 up to 1832, but not since, and the Company has not 
 exercised any control over Plaisterers' work for many 
 ,year§, 
 
18 CEMENTS AND CONCRETES 
 
 Another charter was granted by Queen Elizabeth in 
 1559, but it has been lost, and there is no record of 
 the contents. The Queen granted a new charter in 
 1597, which confirmed the privileges of the Company, 
 and extended the authority of the Master and Wardens 
 to and over all persons exercising the art of plaisterers, 
 as well English as aliens and denizens inhabiting and 
 exercising the said art within the City and suburbs and 
 liberties, or within two miles of the City. 
 
 THE PEESSNT COAT OP ARMS, 
 
 Charles II., by a charter dated June 19, 1679, con- 
 firmed the privileges granted by the previous charters. 
 Having in view the rebuilding of the City, he forbade 
 any person to carry on simultaneously the trades of 
 a mason, bricklayer or plaisterer, or to exercise or carry 
 on the art of a plaisterer without having been appren- 
 ticed seven years to the mystery. The jurisdiction of 
 the Company was extended to three miles' distance 
 from the City. 
 
 There were two orders made by the Court of Alder- 
 men (exemplified under the mayoralty seal, April 1) 
 
INTRODUCTORY 
 
 19 
 
 1585) for settling matters in dispute between the tilers 
 and bricklayers and the plaisterers as to interfering in 
 each other's trades. The observance of these orders 
 was enforced by an order of the Privy Council dated 
 June 1, 1613, and a general writ or precept issue to the 
 * same effect on August 13, 1613. 
 
 Indian Centre-Piece. 
 
 There was also an order of the Court of Aldermen 
 (29 Elizabeth, February 14, 1586-7) relating to the 
 number of apprentices to be kept by members. 
 
 An act of Common Council was passed, under date 
 of 18 James I., October 5, 1620. 
 
 An act of Common Council (6 "William and Mary, 
 October 19, 1694) was also passed to compel all persons 
 using the trade of plaisterer in the City of London, or 
 
20 
 
 CEMENTS AND CONCRETES 
 
 the liberties thereof, to become free of the Company 
 under penalty to be recovered as therein mentioned. In 
 the East the Art of ornamental plastering was well 
 known and almost universally practiced before Mahom- 
 et established a new order of things, and the enriched 
 plaster work of India, Persia and other Eastern Em- 
 pires are evidences of the high character of the work- 
 manship of the Oriental workers in plaster. The 
 Arabian and Moor brought back the Art of the Western 
 World in the early part of the thirteenth century, 
 and it is to them we owe the splendid plaster work of 
 the Alhambra and other work still in existence in Spain. 
 In the Mosque at Medina, built in 622, are still to be 
 seen some fine specimens of old plaster work that was 
 wrought on the building at the time of its completion. 
 The Mosque of Ibu-tubun, Cairo, Egypt, which was fin- 
 ished in A. D. 878, abounds with beautiful plaster work. 
 It contains a number of arches and arcades, the capi- 
 tals of which, like the rest of the building, are enriched 
 wdth plaster buds and flowers made in elaborate de- 
 signs. Even in Damascus, thai old and far-off City 
 indulged in ornamental plaster-work when the people 
 of Western Europe were cutting one another's throats 
 for political ascendency. We illustrate a few examples 
 of old work taken from existing specimens. These will 
 to some extent, give an idea of what the old plasterers 
 could do. See illustrations attached. 
 
 During the middle ages in Europe plastering and 
 stucco existed only as a craft, and its highest function 
 was to prepare a surface to be painted on. Sometimes 
 it was used as an external protection from the weather 
 but rarely was it employed for direct ornament. Some- 
 times small ornaments were carved in plaster of Paris, 
 but it played no important part in decorative Art, 
 
INTRODUCTORY 
 
 21 
 
 excepting perhaps, as gesso, though this belonged rather 
 to the painter than the plasterer. Nor was it until the 
 commencement of the Renaissance in Italy that it 
 showed any symptoms of revival. 
 
 ■Arabesoue from the Great Mos^iUE, Damascus. 
 
 With the commencement of the fifteenth century old 
 learning and old arts began to be studied, the discovery 
 of the art of printing and the consequent multiplication 
 of the copies of the lore heretofore looked up in old 
 manuscripts gave invention and progress new life, 
 
22 
 
 CEMENTS AND CONCRETES 
 
 which has lasted until the present day. Italy has al- 
 ways been the nursing mother of plasterers, and in Mr. 
 G T. Robinson's ''Glimpse of the History of the Art 
 and Craft/' he has shown something of her great and 
 glorious past, and how she sent her sons over almost 
 all Europe to raise the art and status of this craft. 
 
 Persian Centre- Pifxe. 
 
 Even during the depressing times of her history she 
 religiously preserved its ancient traditions and pro- 
 cesses, and in almost all her towns there was some one 
 or two plasterers to whom was confided the restoration, 
 the repair and the conservation of its frescoes or its 
 stuccos. The art dwindled, but it survived. So late 
 as 1851 an English architect, when sketching in the 
 
INTRODUCTORY 
 
 23 
 
 Campo Santo at Pisa, found- a plasterer busy in lov- 
 ingly repairing portions of its old plaster work, which 
 cime and neglect had treated badly, and to whom he 
 applied himself to learn the nature of the lime he used. 
 So soft and free from caustic qualities w^as it that the 
 painter could work on it in true fresco painting a few 
 days or hours after it was repaired, and the modeller 
 used it like clay. But until the very day the architect 
 was leaving no definite information could he extract. 
 At last, at a farewell dinner, when a bottle of wine 
 had softened the way to the old man's heart, the plas- 
 terer exclaimed, ^^And now, signor, I will show you 
 my secret!" And immediately rising from the table, 
 the two went off into the back streets of the town, when, 
 taking a key from his pocket, the old man unlocked a 
 door, and the two descended into a large vaulted base- 
 ment, the remnant of an old palace. There amongst 
 the planks and barrows, the architect dimly saw a row 
 of large vats or barrels. Going to one of them, the old 
 man tapped it with his key; it gave a hollow sound 
 until the key nearly reached the bottom. There, sig- 
 nor! there is my grandfather! he is nearly done for.'' 
 Proceeding to the -next, he repeated the action, saying : 
 ' ^ There, signor ! there is my father ! there is half of him 
 left." The next barrel was nearly full. That's me! 
 exclaimed he; and at the last barrel he chuckled at 
 finding it more than half full: ''That's for the little 
 ones, signor!" Astonished at this barely understood 
 explanation, the architect learned that it was the cus- 
 tom of the old plasterers, whose trade descended from 
 father to son for many successive generations, to care- 
 fully preserve any fine white lime produced by burning 
 fragments of pure statuary, and to each fill a barrel for 
 his successors. This they turned over from time to 
 
24 CEMENTS AND CONCRETES 
 
 time, and let it ain — slake in the moist air of the vault, 
 and so provide pure old lime for the future by which 
 to preserve and repair the old works they venerated. 
 After-inquiries showed that this was a common prac- 
 
 PoRTiON OF A Ceiling from Teheran, Persia. 
 
 tice in many an old town, and thus the value of old 
 air-slaked lime, such as had been written about eighteen 
 hundred years before, was preserved as a secret of the 
 trade in Italy, whilst the rest of Europe was advocating 
 
INTRODUCTORY 
 
 25 
 
 the exclusive use of newly burnt and hot slaked lime. 
 Was there in the early part, indeed even in the middle 
 
 DiArFKED Pi aster I'anei i int. in riiE Aihamuka, Sprain, Thiriff-MH Cf.nturv. i 
 
 of the present century, any plaster image seller who was 
 not an Italian? Indeed, at this present time^ almost 
 
26 
 
 CEMENTS AND CONCRETES 
 
 all the * ^ f ormatore ' ' or piece moulders for the majority 
 of the sculptors of Europe are of Italian nationality or 
 descent, and chiefly by these has the national craft been 
 maintained. 
 
 When after the long European wars of the eighteenth 
 and the commencement of the nineteenth century Italy 
 had rest and power to ^^make itself" (faro de se), the 
 first revival of its industry was felt by her plasterers, 
 and as there was then, as now, more workmen than 
 
 Plastkr Frieze in Mosque of Sultan Hasan. Fourteenth Century. 
 
 work, they emigrated to the neighboring countries; and 
 the major part of the plasterers along the Revieda, in 
 the southern provinces of Germany and Austria, are 
 Italians who go off with and return with the swallows, 
 to earn that wage the poverty of their own country 
 cannot afford them. With this brief historical sum- 
 mary I conclude the Introductory notice, and will now 
 pass on to the more practical domain of the Plasterers' 
 Art. 
 
MATERIALS. 
 
 IJMES, CEMENTS^ MORTARS^ SAND, PLASTERS AND LATHS. 
 
 LIMES. 
 
 The Lime Principally Used for internal plastering 
 is that calcined from carbonate of lime, in v/hich the 
 impurities do not exceed 6 per cent., and is known as 
 fat lime, pure lime or rich lime. It is unfit for any 
 purpose where strength is required, or in situations 
 where it is exposed to the weather, as it has no setting 
 power, and is easily dissolved by wet. 
 
 Hydraulic Limes are those which, in order to set, do 
 not require any outside influences, their own chemical 
 composition of lime and silica^ when burnt, being suf- 
 ficient for the purpose. The name is given for their 
 capability of setting and hardening under water. Hy- 
 draulic limes are obtained mostly from the lias. 
 
 Good Hydraulic Limes are obtained from many 
 places in the United States and Canada, the best 
 known is ^^The Rosendale Hydraulic Cement.'' 
 
 Artificial Hydraidic Limes may be made by mixing 
 a. sufficient quantity of clay with pure lime to obtain 
 a composition like that of a good natural hydraulic 
 limestone. The lime^ if soft, may be mixed with the 
 clay and burnt raw, or, as is more usual, may be burnt, 
 slaked, ground, and then mixed with the clay and re- 
 burnt. 
 
 The Purer the Lime the quicker will it slake. Great 
 care should be taken that the lime is properly burnt 
 or otherwise it will not slake properly, and will prob- 
 ably ''blow'' in the work. 
 
 27 
 
28 
 
 CEMENTS AND CONCRETES 
 
 The Perfect Slaking of the burnt lime before being 
 ^jsed is very important, as it will slake eventually, and 
 cause blisters in the work. In order to effect thorough 
 slaking, the lime should be ^'run" as soon as the build- 
 ing is commenced. It should not be used unless it has 
 been slaked at least three weeks. 
 
 A Bushel of Lime requires in slaking about a gallon 
 and a half of water. 
 
 Lime which Slakes Quickly and with great heat is 
 generally considered to be the best for plasterers' work. 
 
 When Lime Falls in dry weather without any 
 sufficient apparent moisture, it is considered to foretell 
 rain. 
 
 The Lime Should Be Run in couch on the site, where 
 it can be seen by the architect. Care should be taken 
 that as much lime is run as is required for the whole 
 of the building. 
 
 The Plasterer^ partly, perhaps, to avoid the money 
 outlay, and partly to avoid the necessity of having to 
 cart away any lime, has a tendency to run an insuf- 
 ficient quantity of lime. The result of this is that he, 
 commencing at the top, the usually less important part 
 of the building, has used up his lime by the time he 
 has reached the principal rooms on the ground floor, 
 and has to have recourse to possibly insufficiently sea- 
 soned lime, with an unfortunate effect on the work, as 
 stated above. 
 
 SAND. 
 
 The Functions of Sand as used in plaster are (1) the 
 production of regular shrinkage and the prevention of 
 excessive shrinkage, otherwise cracking is the result 5 
 (2) to form channels for the crystallizatioii. 
 
MATERIALS 
 
 Sand should be clean, sharp, and hard. The size of 
 the grains does not influence the strength of the mortar, 
 but, of course, the finer the plaster is required to be 
 the finer must the sand be. Fine sand is best for hy- 
 draulic lime and coarse for fat limes, coarse stuff and 
 Portland cement for floating. Uniformity of size is 
 not desirable. 
 
 The Proportiofi of Sand to Lime will vary consider- 
 ably, according to circumstances, and is difficult to de- 
 termine. One part of lime to two parts of sand is a 
 usual mixture. 
 
 Sand is Cheaper than Lime, and it must be remem- 
 bered that this is an inducement to use too large a pro- 
 portion of sand in order to cheapen the plaster. 
 
 Sand is Obtained from rivers, pits, or the sea. Sea 
 sand, or that from tidal rivers, should be avoided, as 
 the salt never dries, and will come out on the surface 
 sooner or later, discoloring the wall papers, paint, etc., 
 and keeping the walls damp. 
 
 River Sand is often used, but it is not to be recom- 
 mended, because the sharpness of the grains is worn 
 off by the action of the running water. It is easily 
 obtained, however, and the light color of much river 
 sand causes it to be used in internal work with the 
 v»-hite cements. 
 
 Pit Sand is the best. It sometimes contains loam or 
 clay, which should be carefully washed out. 
 
 All Sand for High-Class Plastering is best washed. 
 
 HAIR. 
 
 Hair is used in plaster in order to bind it together. 
 
 Good Hair should be long, curled, strong, and clean. 
 Ox or cow hair is most generally used, and there are 
 three qualities. 
 
30 
 
 CEMENTS AND CONCRETES 
 
 It Should Be Well Separated before being mixed 
 Avith the plaster, and care should be taken in the mix- 
 ing that the hairs are not broken. 
 
 CEMENTS. 
 
 Portland Cement, with a large proportion of sand, 
 as much as 90 per cent., is useful for internal work; 
 it may be used as a backing for a thin floating of the 
 white cements. 
 
 The Heavier and Slower in Setting cements are gen- 
 erally the stronger; but in such plasterer's work as 
 rendering walls the quicker setting cements may be used 
 without disadvantage. 
 
 Roman Cement is a natural" cement. It is liable 
 to effloresce on the surface, but is useful where quick 
 setting with expansion is required, as in underpinning 
 or repairs, without any great ultimate strength. 
 
 Other ^'Natural Cements'' very similar to Roman 
 are Medina, Rosendale, Windsor, etc., and are also use- 
 ful where quick setting is required. 
 
 The Use of the Natural Cements is much restricted 
 at the present time as compared with artificial cements, 
 such as Portland. 
 
 Parian Cement is valuable for internal work, by rea- 
 son of its hardness, nonporosity, and quick setting 
 properties. It is hence useful in cases where the walls, 
 mouldings, etc., have to stand rough usage. It is also 
 washable. This cement will not admit of being re- 
 worked. 
 
 Eeene's Cement is one of the most useful of the 
 artificial cements. It is harder than the other kinds 
 made from plaster of Paris, and is much used for pilas- 
 ters, columns, etc.^ as it sets quickly and can be pol- 
 ished, and takes paint excelleiitly. 
 
MATERIALS 
 
 31 
 
 Martin's Cement is much the same as Keene's, and 
 used principally for dadoes, etc. In proportion to its 
 bulk it covers a large proportion of surface. It can 
 be painted, etc., as Keene's. 
 
 Robinson's Cement has many advantages, among 
 which are its fire-resisting qualities and suitability for 
 use on concrete. It is also cheaper than other like 
 cements. 
 
 Adamant is another white cement, which is useful for 
 work where hardness, facility of application, quick dry- 
 ing, and a fine surface are required. 
 
 The Above Cements have plaster of Paris (calcined 
 gypsum) for their base, and are only adapted for in- 
 ternal uses, to which they are eminently suited. They 
 can all be brought to a good surface, and can be painted 
 almost at once. 
 
 Selenitic Cement is based on the property which sul- 
 phate of lime as plaster of Paris, when added to lime 
 possessing hydraulic properties, has of causing its more 
 rapid setting. It also increases the proportion of sand 
 which it will bear. It is useful in plastering as a back- 
 ing for the white cements, such as Parian. 
 
 PLASTER OF PARIS. 
 
 Plaster of Paris is made by the gentle calcination of 
 gypsum, previously ground. It is known in the plas- 
 tering trade as plaster. 
 
 The Principal Use of Plaster of Paris is in mixing 
 with ordinary putty in order to produce greater rapid- 
 ity in setting, but the fast setting plasters of Paris are 
 not, of course, the best for working with, nor do they 
 become as hard as the slower setting. 
 
 The Proportion of Plaster of Paris to ordinary lime 
 putty varies greatly from about 1 in 4 to 1 in 20, de- 
 
32 CEMENTS AND CONCRETES 
 
 pending on circumstances, such as the state of the 
 weather, the speed with which the work has to be fin- 
 ished, etc. It is also used largely for cast ornaments, 
 in cornices, etc., and, by reason of its quick setting/and 
 expansion when setting, for stopping holes, etc. 
 
 LATHS. 
 
 Pine, Cedar and Metal are used for laths for mod- 
 ern work; only the best quality should be used. 
 
 Oak Laths and Cypress formerly used, are very liable 
 to warp. 
 
 The Defects to Be Avoided in Laths are sap, knots, 
 crookedness, and undue smoothness. The sap decays; 
 the knots weaken the laths; the crookedness interferes 
 with the even laying on of the stuff; and the undue 
 smoothness does not give sufficient hold for the plaster 
 on the lath. 
 
 Riven Laths, split from the log along its fibres, are 
 stronger than sawn laths, as in the latter process the 
 fibres of the wood are often cut through. 
 
 Laths May Be Obtained in Three Sizes, namely: 
 '^Single'' (average 1-8 in. to 3-16 in. thick), ^^lath and 
 half" (average in. thick) and ^^double'' (% in. to 
 % in. thick). 
 
 The Thicker Laths should be used in the ceilings, be- 
 cause of the strain upon them, and the thinner in ver- 
 tical partitions, etc., where there is but little strain. 
 Where walls and partitions have to stand rongli usage 
 the thicker laths are necessary. 
 
 Laths Are Usually Spaced with about % in. between 
 them for key. 
 
 A Bunch of Laths usually contains a hundred pieces, 
 and such a bunch nailed, with butt joints, cover about 
 
MATERIALS 
 
 33 
 
 4^ yds. super., and requires about 500 nails if nailed 
 to joists 1 ft. from center to center. 
 
 The Lengths of Laths vary from 3 ft. to 4 ft., the 
 latter the usual length. 
 
 Laths Are Best Nailed so as to Break Joint entirely, 
 as for various reasons there is a tendency to crack along 
 the line of the joints if nailed with the butt ends in a 
 row. This may be obviated by using 3 ft. and 4 ft. laths 
 together. Ceilings are much stronger if so nailed. 
 Laths, however, are usually nailed in bays, about 4 ft. 
 or 5 ft. deep. 
 
 Every Lath should be nailed at each end, and wher- 
 ever it crosses a joist or stud. 
 
 Lap Joints at the end of laths, which are often made 
 in order to save nails, should not be allowed as this 
 leaves only i/4 i^- for the thickness of plaster. Butt 
 joints should always be made. 
 
 Joists J etc, J which are thicker than 2 in. should have 
 small fillets nailed on their under side or be counter- 
 lathed, so that the timber surface of attachment be re- 
 duced to a minimum and the key be not interfered with. 
 
 Walls which are liable to damp are sometimes bat- 
 tened or strapped. 
 
 Metal Lathing is now extensively used for its fire- 
 proof qualities and freedom from rot or harboring of 
 vermin. 
 
 Lathing Nails are usually of iron — galvanized, cut, 
 wire, or cast; where oak laths are used, the nails 
 should be galvanized or wrought. Galvanized nails 
 should also be used with white cement work. Zinc 
 nails, which are expensive, are used in very good work, 
 because of the possibility of the discoloration of the 
 plaster by the rusting of iron nails. 
 
34 CEMENTS AND CONCRETES 
 
 The Length of Lathing nails depends on the thick- 
 ness of the laths, % in. long nails being used for shin- 
 gle laths, 1 in. nails for lath and half iaths, and li/4 i^- 
 nails for double laths. 
 
 MEMORANDA. 
 
 One Yard Rendering requires 1-3 cu. ft. lime, cu. 
 ft. sand, oz. hair, and 1% gal. water. One yard 
 render and set requires % cu. ft. lime, % cu. ft. sand, 
 3 oz. hair, and 2 gal. water. 
 
 One yard render, 2 coats and set, requires 3-5 cu. ft. 
 lime, 2-3 cu. ft. sand, 3 oz. hair, and 2^/2 gal. water. 
 
 One yard render and float requires 1/2 cu. ft. lime, 
 % cu. ft. sand, 2^/2 oz. hair, and 2^2 g^l- water. 
 
 One yard render, float and set, requires 3-5 cu. ft. 
 lime, % ft. sand, 3% oz. hair, and 2% gal. water. 
 
 Two bushels of gray lime, or 3 of blue lias lime, or 
 3 of Roman cement, or 2 of Portland cement, or 14 lbs. 
 plaster of Paris, equal one bag. 
 
 1 lb. hair is allowed to 2 cu. ft. of coarse stuff for 
 good work, and 3 cu. ft. for common work. 
 
 100 yd. super, of lime whiting, if once done requires 
 1^ cu. ft. of lime; and if twice done, 2 cu. ft. of limCo 
 
WORKMANSHIP. 
 
 EXTERNAL WORK. 
 
 Portland Cement is unquestionably the best material 
 for external plastering. For weather resisting proper- 
 ties, strength, and capacity for moulding and painting, 
 it is unequalled. 
 
 The Cement for Rendering requires to be mixed with 
 sand in the proportion of about 1 of cement to 4 of 
 sand, but for projecting cornices, etc., the proportion 
 of sand should be only about half this, as, of course, the 
 addition of sand decreases the adhesive power of the 
 cement. The fining coat is mixed in the proportions of 
 about 2 to 1. 
 
 External Facades in Portland Cement are usually 
 laid in two coats ; the first coat, known as the rendering 
 or floating coat, is worked to screeds, and is from i/^ 
 in. to % in. thick. This coat must be carefully cleared 
 and well wetted for the second coat, which is known 
 a^ the finishing or fining coat, which is about 3-16 in. 
 thick, and is worked with a hand float. 
 
 The Key for External Plastering on brick work may 
 be obtained either by building the walls roughly with 
 the mortar projecting or by raking the joints at least 
 % in. Stone work should be hacked. 
 
 The Surface Must Be Well Wetted, or the wall will 
 absorb the water from the rendering coat. 
 
 There is a Tendency to Mix Fat Lime with Portland 
 cement in order to make it work more freely, but this 
 should not be allowed. 
 
 35 
 
36 
 
 CEMENTS AND CONCRETES 
 
 Stucco is the term which is loosely applied to all 
 kinds of external plastering, whether of lime or cement. 
 An enormous amount of stucco" was done at the end 
 of the eighteenth century and the beginning of the 
 nineteenth, but is now out of fashion, except for coun- 
 try and suburban residences. The term is also applied 
 to some forms of internal plastering. The principal 
 varieties of stucco are common, rough, bastard, and 
 trowelled, but cement has largely superseded them. 
 
 Common Stucco was principally employed for ex- 
 terior work, and was composed of 1 part hydraulic lime 
 and 3 parts sand. The surface of the wall should be 
 rough and wet as for Portland cement rendering. 
 
 Rough Stucco was used on a floated ground in po- 
 sitions where it was desired to imitate stone. It was 
 worked with a hand float covered with a material such 
 as rough cloth, in order to raise the sand and produce 
 a stone-like appearance. Cement is now used for the 
 same purpose. 
 
 Bastard Stucco and Trowelled Stucco were chiefly 
 adapted for painted internal work, and each is laid on 
 the second coat as a finish; the first and second coats 
 being as for ordinary three-coat work. 
 
 Troivelled Stucco consists of 1 part sand to 2 parts 
 fine stuff. It is worked with the hand float till a very 
 fine smooth surface is produced. 
 
 Bastard Stucco contains a little hair and has not so 
 much labor expended upon it. 
 
 Sgraffito is the name given to ornament which is 
 scratched on plaster work. Patterns may be obtained 
 by laying differently colored coats (usually two or 
 three) on ordinary roughened Portland cement ren- 
 dering, and removing portions of each coat in the form 
 of a pattern. 
 
WORKMANSHIP 
 
 37 
 
 The Design for the Sgraffito is applied in a cartoon 
 and pricked and pounced on the work in the usual way. 
 If more colors are required than the coats provide, the 
 background may be washed and a combination of 
 sgraflSto and fresco used. The cutting should be deep 
 enough to give a sharp appearance, but not too deep 
 tc hold dirt and wet. 
 
 Rough Cast, also known as pebble dashing, is the 
 coarsest kind of external plastering. It is very durable 
 if properly mixed. Its use in this country dates back 
 to very early times. The wall is first plastered, and 
 gravel, shingle, or other materials such as spar, broken 
 bricks and glass bottles, broken pottery, etc., are thrown 
 or dashed at it while it is soft. If the gravel is mixed 
 and laid with the plaster there is a tendency in laying 
 for it to tear the plaster away from the wall, and as 
 the gravel is covered with plaster its appearance is not 
 so good. The lime for rough cast should be weather 
 resisting, and is generally used hot. 
 
 Depeter is a form of rough cast on which the gravel 
 is pressed in by the hand. Ornamental patterns in 
 color may be worked in it. Effective but simple deco- 
 rations for external plaster may be made in various 
 ways. Patterns, such as sunflowers, etc., may be in- 
 cised in it, and a very effective decoration has been 
 obtained by merely tapping the plaster with a scratch 
 six or seven times alternately in a diaper pattern. In 
 half-timber work the plaster is much more pleasing if 
 carefully laid with a carelessly unlevel surface, and, of 
 course, set back from the timber face about % in. 
 
 INTERNAL WORK. 
 
 Lime Plastering is compounded of lime, sand, hair, 
 and water. The proportions of these materials vary 
 
38 CEMENTS AND CONCRETES 
 
 according to their nature and the position of the plas- 
 ter. For successful work good materials and skillful 
 mixing are essential. It is applied in one, two, or three 
 coats, and by the number of these the plaster is named. 
 
 The Thinner the Coats of plaster are the better, as 
 the plaster has a better chance of drying and harden- 
 ing. 
 
 One-Goat Work, necessarily the commonest and 
 cheapest, is limited to very inferior buildings, such as 
 outhouses and places where it will not be seen, as be- 
 hind skirtings. One-coat work on laths is specified as 
 ^^lath and lay, ''-or ^^lath and plaster," and on wails 
 simply as ^ ^render." 
 
 TwO'Coat Work is that usually employed in inferior 
 work, such as factories, warehouses, etc., but it is also 
 used for the least important rooms in better class build- 
 ings. Common setting for walls and ceilings is gener- 
 ally used for this class of work. Two-coat work on 
 laths is specified as ^^lath, lay, and set," or '4ath, plas- 
 ter, and set," and on walls as render, and set." 
 
 Three-Coat Work is that used in all good buildings, 
 and forms a most satisfactory wall finish, when well 
 done. Three-coat work on laths is specified as ^4ath, 
 lay, float, and set," or ''lath, plaster, float, and set," 
 and on walls as ''render, float, and set." 
 
 The Processes in Plastering ordinary three-coat work 
 are as follows: 
 
 For the First Coat a layer of well-haired coarse stuff 
 known as pricking-up is laid to a thickness of about 
 % in. This should be laid diagonally and w^ith each 
 trowelful overlapping. If on laths it should be soft 
 enough to be well worked through them to form a key. 
 'The surface is then scratched with a lath to form a 
 key for the next coat in lines abo^it 4 in. apart. It is 
 
WORKMANSHIP 
 
 39 
 
 ready for the second coat when too hard to receive an 
 impression from ordinary pressure. 
 
 The Coarse Stuff used in the first coat is mortar com- 
 posed of sand and lime, usually in the proportions of 2 
 to 1, with plenty of hair, so that when a trowelful is 
 taken up it holds well together and does not drop. 
 
 The Second Coat known as floating, is next laid. 
 Four processes are involved in laying the second coat, 
 namely: Running the screeds, filling in the spaces, 
 scouring and keying the surface. The scouring is done 
 with a hand float, the surface being sprinkled by a 
 brush during the process. The keying consists in lining 
 the scoured surface with a broom or nail float to form 
 an adhesive surface for the finishing coat. 
 
 The Floating is of finer quality than the coarse stuff, 
 it does not contain as much hair, and is used in a softer 
 state. 
 
 The Third Coat is the finishing coat, and is known 
 as the setting coat. Great care must be taken in laying 
 this coat in order to obtain uniformity of surface, color, 
 smoothness, and hardness. The second coat should be 
 uniformly keyed, clean and damp before the third is 
 laid. The processes involved are laying, scouring, trow- 
 elling, and brushing. 
 
 Fine Stuff, which should be used for the finishing 
 coat if the walls are to be papered, consists of pure 
 lime, slaked and then saturated till semi-fluid, and al- 
 lowed to stand till the water has evaporated and it 
 forms a paste. It may then be thoroughly mixed with 
 fine sand in the proportion of 3 parts of sand to 1 part 
 of fine stuff. 
 
 Plasterers^ Putty is much like fine stuff, but is care- 
 fully sieved. 
 
40 CEMENTS AND CONCRETES 
 
 Gauged Stuff is plasterers' putty and plaster of 
 Paris in the proportion of three or four to one. If too 
 much plaster is used it cracks in setting. It is largely 
 used in cornices, and also where the second coat is not 
 allowed time to dry, and the work has to be done in a 
 hurry. As it sets rapidly, it must be mixed in small 
 quantities. 
 
 The White Cements (such as Parian, etc.), of which 
 plaster of Paris is the base^ are usually laid in two 
 coats; the first, of cement and sand, is about I/2 in. to 
 34 in. thick, and the second of the cement neat. 
 
 Cracks in Plaster Work are caused, apart from the 
 natural settlement of the building and the use of in- 
 ferior materials and workmanship, by the too fast dry- 
 ing of the work, the laying of the plaster on walk of 
 too great suction, by laying one coat on another before 
 the lower one has properly set, and by the use of too 
 little sand. 
 
 Joist Lines on Ceilings are very unsightly, and are 
 caused by the filtration of dust through the intervening 
 spaces. They may be prevented by using a good thick- 
 ness of plaster, and working it well, that it may be hard 
 and nonabsorbent and as the dust comiCS from the top 
 and filters through, by protecting the upper side of the 
 plaster. 
 
 Pugging consists in laying a quantity of plaster be- 
 tween the joists of a floor or between the studding of 
 a partition for the purpose of preventing the passage 
 of sounds or odors. In the first case, which is the more 
 common, the plaster is laid on thin, rough boards fixed 
 to battons on the sides of the joists; in the second case, 
 which is called ' ^ counterlathing " in some parts of the 
 country, by plastering on laths nailed between the par- 
 tition studs. 
 
WORKMANSHIP 
 
 41 
 
 Pugging Should Not Be Used Too Wet, There are 
 three objections to this — the first that it takes a very 
 long and inconvenient time in drying; and secondly, 
 that the water is liable to be absorbed by the wood, 
 and to cause it to rot; and thirdly, it is liable to crack 
 in the drying. For this last reason it should always be 
 laid in two coats. 
 
 The Battons should all be nailed at an equal depth 
 from the tops of the joists, and the plaster should be 
 of an equal thickness throughout, which is obtained by 
 drawing a trammel along the joists. 
 
 Mineral Wool is far more sanitary than ordinary 
 pugging, has considerable sound and fire resisting qual- 
 ities, it does not absorb moisture and so rot the laths 
 and timbers, is a preventive of vermin, and is light in 
 weight. 
 
 Lime Whiting or Whitewash which is lime dissolved 
 in water, is a useful and sanitary covering for the 
 walls of cellars and outhouses. 
 
 If Lime-Whited Walls Have to Be Plastered, the wall 
 should be first carefully picked, as if the lime is left on, 
 the plaster is liable to scale. 
 
 Fibrous Plaster is composed of plaster, canvas, wood, 
 etc. It is light and dry and can be quickly fixed. 
 
 Ornamental Plaster ceilings may be either modelled 
 throughout in situ, or cast in pieces, or formed by work- 
 ing the ornament on a previously formed flat ceiling. 
 The first method is the more costly, but more feeling 
 is thereby obtained. 
 
1 
 
 SPECIFICATION CLAUSES. 
 
 MATERIALS. 
 
 1. The sand for plastering is to be fresh-water river, 
 or pit sand, and free from earthy, loamy, or saline 
 material, to be well screened, and to be washed if re- 
 quired. 
 
 2. The laths to be straight-riven or saron pine of the 
 strength known as lath and half, well nailed with lin. 
 oxidized lath nails, properly spaced for key, and with 
 butt-headed joints, double nailed, and breaking joint 
 in 3 ft. widths. 
 
 The lathing to be Expanded metal,'' No. — gauge. 
 
 3. The lime for coarse stuff to be approved well- 
 burnt grey-stone lime, to be run at least one month 
 before being required for use, to be kept clean, and 
 well mixed as required with two parts sand and one 
 part lime. 
 
 4. The coarse stuff for ceilings, lath partitions, and 
 elsewhere where directed to have 1 lb. of good, long 
 curled cowhair, free from grease, leading, or other im- 
 purities, well beaten in, and incorporated with every 
 3 cu. ft. of coarse stuff. 
 
 5. Approved lime, free from lumps, flares, or core, 
 is to be used for setting, putty, etc., and is to be run 
 at least one month before being required for use. 
 
 6. The Portland cement is to be of the best quality 
 and description for plastering purposes, from an ap- 
 proved manufacturer, and must on no account be used 
 fresh, but be spread out to cool for at least .... weeks 
 in a dry shed or room. 
 
 42 
 
SPECIFICATION CLAUSES 43 
 
 All suitable cement and all other materials required 
 in plastering are to be of the best of their respective 
 kinds and descriptions. 
 
 7. Provide all plasterers' plant, necessary scaffold- 
 ings, tools, moulds, running rules, straight edges, tem- 
 plates, etc., of every kind and description necessary for 
 the proper execution of the work. 
 
 WORKMANSHIP. 
 
 8. Lath, plaster, float, and set all wood joist ceil- 
 ings, soffits, and stud partitions, and finish partitions to 
 line in trowelled stucco. 
 
 The concrete ceilings and soffits are to be well hacked 
 for key and floated and set in gauged stuff, and the 
 concrete partitions are to be floated and set. 
 
 Do all dubbing out where required to concrete ceil- 
 ings, soffits, and partitions in gauged stuff. 
 
 The concrete soffits of strong rooms to be finished 
 with one coat of putty gauged with plaster only. 
 
 9. Cover all chases containing pipes, etc., with heavy 
 wire lathing suitable for plastering on, securing the 
 same in a thorough manner. The wire lathing to be 
 wetted in lime water before being put on. 
 
 10. Render, float, and set all walls where not other- 
 Mdse described. The walls to ...... to be finished in 
 
 trowelled stucco. 
 
 11. All cornices and moulded work throughout to 
 be run clean and accurately to the sections given. 
 
 All mitres and returns to be truly worked, and all 
 enrichments and modelling to be to architect's ap- 
 proval, and strictly in accordance with the models and 
 instructions given. 
 
 Run moulded plaster cornices .... girt to .... rooms. 
 
44 CEMENTS AND CONCRETES 
 
 with all mitres, returned, stopped, and mitred ends, 
 etc., as required. 
 
 The cornices to .... are to be run in fibrous plas- 
 ter, fitted and fixed with proper oxidized nails, and 
 made good to. 
 
 12. All narrow reveals, splays, and returns to be 
 finished in suitable cement on a Portland cement back- 
 ing. 
 
 Eun strong cement angles and arrises on Portland 
 cement backing to all projecting angles except the fol- 
 lowing, which are to be moulded, viz. : 
 
 Run rounded angles to of 3 in. girt in strong 
 
 cement as before. 
 
 Run avolo moulded angles 3 in. girt with 2 in. wings 
 to .... opening, finished with moulded stops and short 
 lengths of angle and arris to detail, all in best cement. 
 
 All exposed surfaces of concrete lintels and girder 
 casings are to be finished in white cement internally 
 and Portland cement externally, kept flush with faces 
 of brickwork; all with arrises and angles excepting 
 those otherwise described. 
 
 13. Run Portland cement flush skirting 9 in. high 
 to basement, where plastered, with flush head to top and 
 trowelled face. 
 
 The skirting to to be 12 in. high and 1 in. 
 
 projection, sunk and twice moulded in white on Port- 
 land cement backing. 
 
 Float off the concrete floors of .... in Portland ce- 
 ment to the required level to receive mosaic and the 
 pavings. 
 
 14. Run all necessary quirks, spla>s, arrises, etc., 
 and make good to all mantelpieces; cut away for and 
 make good after all other trades^ and cut out and make 
 
SPECIFICATION CLAUSES 
 
 good all cracks, blisters, and other defects, and leave 
 plaster work perfect at completion. 
 
 15. Ding" walls where shown on plans with a coat of 
 Portland cement 1 part, sand 2 parts, pea-grit 1 part, 
 and ground chalk 1 part. Finish walls where shown 
 with a rough coat of Portland cement 1 part and sand 
 3 parts, and rough cast with fine pea-grit. 
 
 16. Stop and twice lime white soffits and walls of . . 
 
 17. Twice distemper white all ceilings, soffits, and 
 cornices, and twice distemper to approved tints the 
 walls of all rooms. 
 
PEEPARATION OF BILL OF QUANTITIES. 
 
 MATERIALS. 
 
 Materials and Plant, etc. — 1 to 7. These items ap- 
 pear in the heading under Specification clauses. 
 
 WORKMANSHIP. 
 
 Ceilings, Partitions, and Walls. — 8 and 10. These 
 are all billed at per yd. super, including lathing where 
 required, also hacking concrete and any dubbing in the 
 latter, stating the thickness. Keep all plaster work 
 less than 12 in. wide separate in narrow widths.'' 
 
 Wirelathing. — 9. These being narrow, it is advisable 
 to measure them at per ft. run, stating the width. 
 
 Cornices. — 11. Cornices and mouldings under 12 in. 
 girt are measured at per ft. run and those over this 
 girt at per ft. super, number all mitres, stoppings, etc. ; 
 those to the running items following same, and those 
 to the superficial items averaged for girt. See whether 
 bracketing is required; if so, take the girt required at 
 per ft. super., numbering angle brackets to mitres and 
 returned ends, and averaging the girt. 
 
 Measure the walls and ceilings less by the height and 
 projection of the cornice, and add to the girt of the 
 cornice 2 in. (i. e., 1 in. for each edge) for the portion 
 up to the ceiling and walls. 
 
 Enrichments are measured at per ft. run, giving the 
 girt and description, and including the modelling. If 
 
 46 
 
BILL OF QUANTITIES 
 
 47 
 
 of exceptional character, a provision for modelling is 
 sometimes inserted. 
 
 Angles, — 12. These appear in bill in feet run with 
 the girt of moulding or bead (if any) and also the 
 widths of returns. Number the stops, mitres, etc., al- 
 lowing each to follow the item to which they apply. 
 
 The finishings to concrete beams, lintels, etc., is kept 
 separate as in narrow widths to beams, etc./' and all 
 arrises, etc., being measured at per ft. run. 
 
 Skirtings or Dadoes. — 13. Describe skirtings or dadoes 
 giving height and projection, and also finish at top, and 
 measure at per ft. run, numbering all mitres, ends, etc. 
 Include the dubbing with the item. The general wall 
 plastering is deducted for these. 
 
 Floating for mosaic and tile pavings appears in the 
 bill in yard super. 
 
 Quirks. — 14. Labor to splays, quirks, arrises, etc., 
 are measured at per ft. run. 
 
 The attendance on trades is frequently measured in 
 detail, as ^'making good around mantels" or gratings, 
 etc. 
 
 The cutting-out and making good appears at the end 
 of the bill in the form here given. 
 
 Rough Cast. — 15. As clauses 8 and 10. 
 
 Lime Whiting and Distempering. — 16 and 17. These 
 appear in the bill in yd. super. In the case of distem- 
 pering, if the colors are in any way special mention 
 this, and also if in dadoes and filling, taking the di- 
 viding line in feet run. 
 
 Distempering on cornices is usually measured in ft. 
 super., stating the number of tints, and if lines picked 
 out in ft. run ; as is also distempering on enrichments, 
 taking the latter as ''extra to," the distempering to 
 cornices being measured over enrichments. 
 
48 CEMENTS AND CONCRETES 
 
 LATHS GENERALLY. 
 
 General opinion is undoubtedly in favor of split 
 laths, and split laths are sometimes specified by archi- 
 tects for ceilings and partitions. Sawn laths, unless 
 cut from specially selected straight-grained stuff, would 
 most assuredly have weak places from uneven grain, 
 and in order to avoid this weakness the sawn laths 
 would have to be made thicker than split laths, and 
 only the best quality should be used. Oak laths, for- 
 merly used, are very liable to warp. The defects that 
 are to be avoided in laths are sap, knots, crookedness, 
 a.nd undue smoothness. The sap decays; the knots 
 weaken the laths ; the crookedness interferes with the 
 even laying on of the stuff, and the undue smoothness 
 does not give sufficient hold for the plaster on the lath. 
 Riven laths, split from the log along its fibres, are 
 stronger than sawn laths, as in the latter process the 
 fibres of the wood are often cut through. Sawn laths 
 are, however, cheaper than riven laths, and have super- 
 seded them, which is not desirable in good work. Thick 
 laths, because of the strain upon them, should be used 
 in the ceilings, and the thinner laths should be used in 
 vertical partitions, etc., where the strain is but small. 
 Some walls and partitions have to stand rough usage; 
 in such cases the thicker laths are necessary. Laths are 
 usually spaced with about % in. between them for key. 
 A bunch of laths usually contains 360 lin. ft. and such 
 a bunch nailed with butt joints, covers about 4% super, 
 yd., and requires about 400 nails if the laths are nailed 
 to joists 16 in. from center to center. The length of 
 laths varies from 3 ft. to 4 ft. Laths are best nailed so 
 as to break joint entirely, because, for various reasons, 
 there is a tendency to crack along the line of the joints 
 
BILL OF QUANTITIES 
 
 49 
 
 if the laths are nailed with the butt ends in a row. This 
 may be obviated by breaking joints; ceilings are much 
 stronger if the laths are nailed in this way. Laths, 
 however, are usually nailed in bays, about 4 ft. or 5 ft. 
 deep. Every lath should be nailed at each end, and also 
 at the place where the lath crosses a joist or stud. Lap 
 joints at the end of laths, which are often made in or- 
 der to save nails, should not be allowed, as this leaves 
 only 14 ill- for the thickness of plaster. Butt joints 
 should always be made. Joists, etc., that are thicker 
 than two in., should have small fillets nailed to the un- 
 der side, or be counter lathed, so that the timber surface 
 of attachment may be reduced to a minimum and the 
 key not interfered with. 
 
 Lathing nails are usually of iron, and are galvanized, 
 cut, wrought, or cast; where oak laths are used, the 
 nails should be oxidized or wrought. Oxidized nails 
 should also be used with white cem^ent work. Zinc nails, 
 which are expensive, are used in very good work, be- 
 cause of the possibility of the discoloration of the plas- 
 ter by the rusting of iron nails. The length of lathing 
 nails depends on the thickness of the laths, % in. nails 
 being used for single laths, and 1^/4 iii- nails for double 
 laths. 
 
TOOLS AND APPLIANCES USED BY THE 
 PLASTEREE. 
 
 The illustrations shown at Pigs. 1 and 2 show a num- 
 ber of tools and appliances made use of by the plas- 
 terer, and others — special — will be shown further on, 
 when it is necessary to describe and illustrate some 
 speicial process or method of working. The tools the 
 pla^erer requires are many and varied, and may be 
 enumerated about as follows: They consist of moulds 
 for running cornices, and center moulds, which may 
 never be used only in the one piece of work, as the de- 
 signs and styles of cornices and centers are continually 
 changing. As these tools do not cost much, however, 
 the changes do not fall heavily on the workman; but it 
 is as well, whenever it can be done, to charge each 
 mould against its own particular job of work. A good 
 spade and shovel will be absolutely necessary to the 
 plasterer's outfit, and will be among the first tools he 
 will require. These should be light and strong, and 
 well handled, or helved; after using they should have 
 all the lime and mortar cleaned off them, and should 
 be placed away where they will not be exposed to the 
 weather. 
 
 The following list and descriptions of tools will give 
 a new beginner an idea of the kind and character of 
 tools he will be likely to require before he can success- 
 fully carry on the plastering business. Most of these 
 tools will be illustrated further on: 
 
 The Hoes and Drags, — These are tools so well known 
 that they require no description here. They are used 
 
 50 
 
52 
 
 CEMENTS AND CONCRETES 
 
 chiefly for mixing hair in the mortar, and for loosening 
 mortar when too ''stiff/' or when it has developed a 
 tendency to ''set." They are also used for preparing 
 ''putty" and fine "stuff." (See Fig. 2.) 
 
 The Haivk, which is a square board about thirteen 
 inches square, with a short handle on the under side. 
 It is used for holding stuff while the operator is at 
 work. It is generally made of pine or some other light 
 wood; it is made thin on the edges, being beveled from 
 the center on the under side to each of the four edges; 
 the handle should be about six inches long, and one and 
 a half inches in diameter. 
 
 The Mortar-Board is a board similar to a table top^ 
 and is about forty inches square; it is made by joint- 
 ing two or more boards together, which are secured by 
 two battens, and screws or nails. It is used for holding 
 the mortar delivered from the hod direct by the laborer. 
 
 Trowels^ which are of two kinds : the ordinary trowel, 
 which is formed of light sfeel four inches wide and 
 about twelve inches long; this is the laying and smooth- 
 ing tool, and is the most important in a plasterer's out- 
 fit. The other is termed a gauging trowel, and is used 
 for gauging fine stuff for courses, etc. ; it varies in size 
 from three to seven inches in length. 
 
 Of Floats^ which are used for floating, there are three 
 kinds, viz. : the darby, which is not a proper float, is 
 single or double, as may be required; the single being 
 for one man to use, the double for two. The single one 
 should be four feet five inches long, and about four 
 inches wide, with a handle near one end, like a hawk 
 handle, and a cleat near the other end running length- 
 wise of the blade; the long darbys have a hawk handle 
 on each end. The hard float, which is used in finishing, 
 and the quick float, which is used in floating angles. 
 
NO. 2. 
 
54 CEMENTS AND CONCRETES 
 
 The hard float is made of good pine, and has a semi- 
 circular handle on the back; a strip of hard wood is 
 sometimes dovetailed into the blade, and the handle is 
 screwed fast to the strip previous to the latter being 
 driven in the dovetail; this is a good way, as there are 
 no nails then driven through the blade, which, by the 
 rapid wearing of the latter, would soon project above 
 the blade and scratch the plaster where it was intended 
 to have it smooth. The quick float is seldom used in 
 this country; it is shaped like the angle it is intended 
 to work down, afid is a trifle handier for this purpose 
 than the ordinary hard float. 
 
 Moulds, — These are used for running stucco cornices, 
 and are infinite in shape and variety. The reverse of 
 the contour of the cornice is cut out of sheet copper or 
 iron, and is firmly attached to a piece of wood which 
 is also cut out the reverse shape of the intended mould- 
 ing. Their uses will be explained under the head of 
 Operations. Moulds or matrices for leaves, flowers, or 
 other ornaments are made of plaster and glue, or bees- 
 wax; these will be discussed hereafter. 
 
 Center-Moulds are made on the same principle as the 
 reverse moulds for linear cornices, with an arm at- 
 tached which is perforated at different radii to suit the 
 diameter of center-piece. Sometimes the moulds for 
 cornicing are so formed, by placing the plates at an an- 
 gle of fort3^-five degrees, that they will finish the cor- 
 nice right into the angle and f orip the mitre ; more fre- 
 quently, however, the mitres are finished by hand. 
 
 The Pointer is nearly the same shape as a bricklayer's 
 trowel, but it is not so large, being only about four 
 inches long. It is chiefly used for small jobbing, or 
 mending broken or defective vv^ork. 
 
TOOLS AND APPLIANCES 
 
 55 
 
 The Paddle is simply a piece of pine wood less than 
 three inches wide and six long, by one thick ; it is made 
 wedge shaped on one end, the other end being rounded 
 off for a handle. Its use is to carry stuff into angles 
 when finishing. 
 
 Stopping and Picking-Oitt Tools ^ or, as they are fre- 
 quently called, Mitering Tools, are made of fine steel 
 plate, seven or eight inches long, and of various widths 
 and shapes. They are used for modeling, and for fin- 
 ishing mitres and returns to cornices by hand where the 
 moulds cannot work. 
 
 Mitering-Eod. — This is a tool one foot or more long, 
 and about one-eighth of an inch thick, and three inches 
 wide; the longest edge is sharp, and one end is bev- 
 elled off to about thirty degrees. It is used for clean- 
 ing out quirks in mouldings, angles, and cornices. 
 
 The Operator also requires a good whitewashing 
 brush, with a short handle. The best should be ob- 
 tained, as it will prove the cheapest in the end. 
 
 A Scratcher is generally made of short pieces of pine 
 two inches wide and one inch thick; three or four of 
 them are nailed to two cleats, and are placed about an 
 inch apart. The center slat should be about eighteen 
 inches longer than the others, so as to form a handle.' 
 See illustrations. The slats on the opposite end to the 
 handle should be cut off square with one side and point- 
 ed. Its use is to make grooves, or bond in what is called 
 the scratch coat. When completed it has somewhat the 
 appearance of a gridiron. 
 
 Hod. — This is formed by two boards, eleven and 
 twelve inches wide, respectively, and eighteen inches 
 long, the wide board being nailed on the edge of the 
 narrow one, making a right-angled trough; one end is 
 closed, and the end piece is rounded over the top; the 
 
56 
 
 CEMENTS AND CONCRETES 
 
 boards forming the sides are rounded at the opening. 
 A handle about four feet long and two inches in diam- 
 eter is then fastened about two inches forward of the 
 middle nearer to the open end, and a piece of wood 
 called a pad is fitted with a groove on the angle just 
 back of the handle. The object of this block is to pre- 
 vent the arris of the hod from chafing the shoulder of 
 the laborer. Much controversy has taken place among 
 workmen at various times regarding the exact size of 
 hod, but this, I think, should be governed more by the 
 strength of the person who has to use the particular 
 hod than by any fixed rules. Hods for carrying mortar 
 need not be so large as hods intended for carrying 
 bricks. (See No. 2, Fig. 1.) 
 
 Sieve. — This is used for straining through putty for 
 finishing; it requires to be very fine for the purpose. 
 Sometimes a hair sieve is used, but they are not last- 
 ing, and should never be used when a wire sieve is ob- 
 tainable. Sometimes a hair sieve may prove convenient 
 where dry plaster or cements have to be run through a 
 sieve of some kind before it can be used; so, on the 
 whole, the plasterer who desires a full and complete 
 outfit, should provide himself with one good hair sieve, 
 and at least two sieves of wire. (See Fig. 7, No. 1.) 
 
 Sand Screens are usually twenty-one inches wide in- 
 side by about six feet long. On small work they are 
 stood up at an angle of forty-five or more degrees, and 
 the sand is shovelled against them; in some large works 
 the screen is suspended, and one man shovels in the 
 sand and a second one swings or shakes the screen. 
 These screens, to be lasting, should have their sides and 
 ends made of sheet iron, and the bottom should be 
 formed with parallel rods of small round iron having 
 wires running across them at regular intervals. These 
 
TOOLS AND APPLIANCES 57 
 
 cross wires should be attached to the iron rods so as to 
 hold them in place. The parallel rods may be placed 
 at such distances from each other as will be most con- 
 venient for the work in hand. 
 
 Mo7^tar Beds are made of rough lumber of any kind, 
 and should be built partly in the ground, where cir- 
 cumstances will permit. They require to be strongly 
 put together, as they have considerable weight to sus- 
 tain. The writer has seen mortar beds built up with 
 bricks and cement where large works have been under 
 construction. Sometimes, master workmen, who do a 
 large business, and who employ a great number of men, 
 keep a large mortar bed or two in the rear yard of 
 their shop and tool house, in which they keep always 
 on hand a supply of ready-made stuff, which enables 
 them to do small jobs or repairs at a moment's notice. 
 
 The Slack Box, — This is generally made of boards, 
 and is eight or nine feet long, and from two to four 
 feet wide, and twelve or sixteen inches in depth. An 
 opening about eight inches square is left in one end, 
 with a slide door attached, so that it can be opened or 
 closed at pleasure. The opening should be covered on 
 the inside with a grating, so that when the lime is run 
 off no lumps or stones will get through. The grating 
 may be made with iron rods, or may be formed with 
 wooden laths or slats. The bottom of the box should 
 be made as close and tight as rough boards will permit. 
 (See No. 1, Fig. 11.) 
 
 Lathing.i — It frequently happens in towns and coun- 
 try places that the plasterer has to do his own lathing^ 
 or at least have it done under his own supervision, 
 therefore it will be necessary to have something to say 
 on this subject, and on the tools employed by the work- 
 man whose duty it is to prepare the walls for the plas- 
 
58 CEMENTS AND CONCRETES 
 
 terer. These tools need not be extravagant ones or 
 many in number. They consist of the following: 
 
 Lather's Hatchet. — ^This is a small hatchet with a 
 blade not more than one and a half inches wide, and 
 rather larger in proportion than ordinary hatchets. 
 The opposite end to the cutting edge is a hammer, with 
 which the lather drives the nails. Sometimes the face 
 of the hammer end is grooved, which makes it cling to 
 the nails if the latter are not struck fairly on the head. 
 An expert lather, however, will prefer a flat hammer 
 face for driving lath nails. The cutting edge is used 
 for nipping'' off laths when they are too long, or 
 Avhen short spaces of lathing are required to be made. 
 In cutting lath with the hatchet, the workman gives the 
 wood a short sharp blow with the tool at the point 
 where the severance is required, and the lath is in- 
 variably cut at the first blow, if the operator is an ex- 
 pert. (See 0, Fig. 2.) 
 
 Nail Pocket, — Perhaps the best nail pocket a lather 
 can have is made from a portion of an old boot leg cut 
 off to about four inches deep, and having a bottom of 
 semi-circular shape made of wood, and to which the 
 portion of the boot is fastened by means of broad-head- 
 ed tacks. The pocket is fastened to the workman's 
 waist by means of a strap, or other suitable device, and 
 hangs in front of him in a convenient position. Some- 
 times nail pockets are made of canvas, but these are 
 not so handy, as the top is apt to close and then nails 
 are difficult to get at. This never occurs with the boot 
 leg pocket. 
 
 Cut-off Saw. — A cross-cut saw is an indispensable 
 tool to the lather for cutting lath in larger quantities 
 for short spaces, and for rigging up platforms to work 
 on, and for cutting supplementary studding or strips 
 
TOOLS AND APPLIANCES 
 
 59 
 
 where such are necessary. The saw should have rather 
 coarse teeth and have plenty of set. Usually, the lather 
 thinks that almost any old used-up saw is good enough 
 for this purpose, and we find him struggling away with 
 all his strength cutting through a bundle of lath, when, 
 if he had a saw that was worth anything — as a saw — 
 he would perform his labors with about one-half the 
 effort, and one-third of the time. It is all wrong to 
 think of being able to work satisfactorily with inferior 
 or imperfect tools. There is no economy in using tools 
 of this kind, and any lather who fancies he is going 
 to make or save anything by making use of an old 
 buckled, mortar-stained saw, makes a terrible mistake. 
 Get a good saw and keep it in good order, and it will 
 pay you in two weeks. (See X, Fig. 2.) Besides these 
 enumerated, there are many other tools and appliances 
 that the plasterer will require, such as jointing rules, 
 moulding knives, modelling tools, drags, chisels, com- 
 passes, plumb rules, etc. 
 
PLASTER, LIME, CEMENTS, SAND, fiTC. 
 
 Plaster of Paris. — Gypsum, from which plaster of 
 Paris is made, is a sulphate of lime, and is so named 
 from two Greek words — ge, the earth; and epsun, to 
 concoct, i. e., concocted in the earth. In Italy it is 
 known by the name of gesso; in Scotland it is called 
 stucco; in this country it is known as calcined plaster; 
 and in the English trade as plaster. The term plas- 
 ter" will henceforth be used in this book. The writings 
 of Theophrastus and other Greek authors prove that 
 the use of plaster was known to them. A stone, called 
 by Theophrastus gypsos, chiefly obtained from Syria, 
 Avas used by the ancients for converting into plaster. 
 Gypsum is mentioned by Pliny as having been used by 
 the ancient artists^ and Strabo states that the walls of 
 Tyre were set in gypsum. The Greeks distinguished 
 two kinds — the pulverulent and the compact. The lat- 
 ter was obtained in lumps, which were burnt in the fur- 
 naces, and then reduced to plaster, which was used for 
 buildings and making casts. 
 
 Gypsum is found in most countries — Italy, Switzer- 
 land, France, Sicily, The United States, and some of 
 the South American States; also in Newfoundland and 
 Canada. The latter is , said to be the finest deposits in 
 the world. It is found in England in many places. 
 The finest gypsum is called ^ ^ alabaster, " and is soft, 
 pure in color, and fragile.. This white translucent ma- 
 terial is a compact mass of crystalline grains, and is used 
 for making small statuary, vases, and other ornaments. 
 Gypsum is found in immense quantities in the tertiary 
 
 60 
 
PLASTER, LIME, ETC. 
 
 61 
 
 strata of Montmartre, near Paris. This gypsum usual- 
 ly contains 10 per cent, of carbonate of calcium, not al- 
 ways in intimate union with the sulphate, but inter- 
 spersed in grains. This sulphate gives the Paris plas- 
 ter some of its most useful properties. Pantin, near 
 Paris, has large beds of gypsum, one bed being hori- 
 zontal and over 37 ft. thick. 
 
 The term plaster of Paris'' was mainly applied to 
 it because gypsum is found in large quantities in the 
 tertiary deposits of the Paris basin. Another reason 
 is that lime and hair mortar is seldom used in Paris for 
 plaster work, plaster of Paris being used for most kinds 
 of internal and external work. Plaster is known in the 
 color trade as terra alba. Plaster of Paris was known 
 in England by the same name as early as the beginning 
 of the thirteenth century. The gypsum, in blocks, was 
 taken from France, and burnt and ground there. It 
 continued to be burnt and ground by the- users until 
 the middle of the nineteenth century. The burning 
 w^as done in small ovens, and the grinding in a mill, 
 sometimes worked by horse-power, or more often by 
 hand. 
 
 Plaster is the most vigorous as it is the oldest vehicle 
 for carrying down generation after generation the mas- 
 terpieces of art with Avhich the golden age of sculpture 
 enriched the human race. For reproductive uses, plas- 
 ter enables youth to contemplate antiquity in its noblest 
 achievements. Today plaster is revolutionizing indus- 
 trial art for us, and in all probability for those w^ho 
 are to come after us. Plaster, lowly and cheap, but 
 docile and durable, is the connecting agent with this 
 greatest of men's endorsement in the past. Plaster 
 thus employed in duplicating works of marble, pottery, 
 and metal work, is today extending the finest indus- 
 
62 CEMENTS AND CONCRETES 
 
 tries, modern and ancient. Plaster is one of the best 
 known fire-resisting materials for building purposes. 
 After the conflagration at Paris, it was found the beams 
 and columns of wood which had been plastered were 
 entirely protected from fire. In cases where limestone 
 walls had been ruined on the outside by the flames pass- 
 ing through the window openings, the same walls in- 
 ternally escaped almost unscathed owing to their being 
 protected w^th plaster. Plaster in some climates has 
 great lasting properties. The Egyptians covered their 
 granite sometimes, and sand stone always, with a thin 
 coating of stucco. The Greeks coated even their mar- 
 ble temples with plaster, and the plaster portions are 
 now in better preservation than unprotected masonry, 
 particularly at Agrigentum in Sicily. 
 
 Quick and Slow Setting Plaster. — M. Landrin, in giv- 
 ing the results of his long continued studies relative 
 to the different qualities of gypsum, states that the 
 more or less rapid setting of plaster is due to the mode 
 in which it is burned. Its properties are very different 
 when prepared in lumps or in powder. The former 
 when mixed in its own weight of water sets in five min- 
 utes, while the latter under similar conditions takes fif- 
 teen minutes. The reason probably is that plaster in 
 powder is more uniformly burned than when it is in 
 lumps, which tends to prove this fact, that when the 
 latter is exposed longer than usual to the action of heat 
 it sets more slowly. Gypsum prepared at a high tem- 
 perature loses more and more of its affinity for water, 
 retaining, however, its property of absorbing its water 
 of crystallization. Plaster heated to redness and mixed 
 in the ordinary manner will no longer set; but if, in- 
 stead of applying a large quantity of water, the small- 
 est possible portion is used (say one-third of its 
 
PLASTER, LIME, ETC. 
 
 63 
 
 weight), it will set in ten or twelve hours, and becomes 
 extremely hard. To prepare good plaster^ it should not 
 be burned too quick to drive off all its moisture, and 
 for its molecules to lose a part of their affinity for the 
 water. If the plaster is exposed to heat until it has 
 only lost 7 or 8 per cent, of its moisture it is useless, 
 as it sets almost immediately. If, however, the burning 
 is again resumed, the substance soon loses its moisture, 
 and if then exposed to the air it very rapidly retakes 
 its water of crystallization, and absorption continues 
 more slowly. It then sets slowly, but attains great 
 hardness. 
 
 Testing. — The quality of plaster may be tested by 
 simply squeezing it with the hand. If it cohere slight- 
 ly, and keeps in position after the hand has been gently 
 opened, it is good; but if it falls to pieces immediately 
 it has been injured by damp. Although plaster does 
 not chemically combine with more than one-fourth of 
 its vv^eight of water, yet it is capable of forming a much 
 larger quantity into a solid mass, the particles of plas- 
 ter being converted into a network of crystals, mechan- 
 ically enclosing the remainder of the water. Sulphate 
 of lime (plaster) is soluble in water to the extent of 1 
 part in about 450, the solubility being but little influ- 
 enced by temperature. It is on account of this solu- 
 bility in water that cements which have to a large ex- 
 tent plaster for their bases are incapable in this raw 
 state of bearing exposure to the weather. The setting 
 of plaster is due to hydration, or its having but little 
 water to take up to resume a state of consolidation. 
 Plaster is used with hydraulic limes to stop the slaking, 
 and convert the lime into cement. These are then called 
 
 selenitic.'' 
 
 In 100 parts of gypsum there are 46 acid, lime 32, 
 
64 CEMENTS AND CONCRETES 
 
 and water 22 parts. Good plaster should not begin to 
 set too soon, and it should remain for a considerable 
 time in a creamy state. When once set it should be 
 very hard. Plaster should set slowly, as it gives more 
 time for manipulation, but principally because one 
 which sets quickly and swells never becomes so hard 
 as slow-setting material. The quality of plaster can- 
 not be determined by its color, the color being regu- 
 lated by that of the gypsum ; but all things being equal, 
 the whitest and hardest generally yields the best plas- 
 ter. But as the exception proves the rule, it may be 
 mentioned that some plasters (such as Howe's) are of 
 a delicate pink tint, and of a very fine grain, and ex- 
 ceedingly strong when gauged. This pink plaster is 
 much appreciated by many plasterers for making origi- 
 nals, as owing to its fineness and density it is very suit- 
 able for cleaning or chasing up models taken from the 
 clay, and also for durable moulding pieces. One of the 
 whitest plasters known, which is also very close in tex- 
 ture, is that manufactured by Cafl^erata. For cast work 
 the color of plaster is of small moment, because the cast 
 work is sooner or later colored with paint, and more- 
 over, unfortunately daubed over with distemper, or 
 worse still, with whitewash. Coarse plasters are darker 
 in color than fine. Coarse plasters of a sandy nature, 
 and which rapidly sink to the bottom when put in 
 water, contain too much silica, or improperly burnt 
 gypsum, or are derived from a bastard gypsum, and 
 are generally of a weak nature. 
 
 Compressive and Adhesive Strength. — The compres- 
 sive resistance of properly baked plaster is about 120 
 lbs. to the square inch when gauged with neat water 
 and 160 lbs. when gauged with lime water; thus show- 
 ing that lime water hardens and improves the affinity 
 
PLASTER, LIME, ETC. 
 
 65 
 
 of plaster. The adherence of plaster to itself is greater 
 than to stone or brick. The adhesion to iron is from 
 24 to 37 lbs. the square inch. 
 
 French Plaster, — A considerable quantity of French 
 plaster was formerly used in this country but our own 
 is more uniform in quality and cheaper in price, so the 
 use of the French material is somewhat limited. In 
 Paris various kinds of gypsum mortars are in general 
 use, raw gypsum and other materials being often inter- 
 mixed. They also contain free carbonate of lime, ac- 
 cording to the degree of heat to which the raw stone 
 has been subjected. The Hotel de Platres, in Paris, 
 affords a good illustration of the constructive uses to 
 which plaster can be put, some of the blocks being 
 about a hundred years old. 
 
 Limes, — Lime is one of the most important materials 
 in the building trades. Limestone is the general term 
 by which all rocks are roughly classified which have 
 carbonate of lime for their basis. They are obtained 
 from many geological formations, varying in quality 
 and chemical properties. The carboniferous consists 
 of nearly pure carbonate of lime. In the limestone of 
 the lias carbonate of lime is associated with silica and 
 alumina (common clay), in proportions varying from 
 10 to 20 per cent. Carbonate of lime is found in a state 
 of chemical purity in rhombohedral crystals as Iceland 
 spar. It is also found in six-sided prisms, known to 
 mineralogists as arragonite. Its purest form as a rock 
 is that of white marble. Colored marbles contain iron, 
 m.anganese, etc. 
 
 . The lias strata consists of a thin layer of hard lime- 
 stone separated by another of a more argillaceous char- 
 acter, or shale, containing various proportions of car- 
 bonate of lime. 
 
66 CEMENTS AND CONCRETES 
 
 Hydraulic Limes, — Hydraulic limes are those which 
 have the property of setting under water or in damp 
 places, where they increase in hardness and insolubil- 
 ity. The blue lias limQ formation is that from which 
 hydraulic lime is principally made. This lime, while it 
 has excellent hydraulic properties, can hardly be classed 
 as a cement. The stones which produce these limes con- 
 tain carbonate of lime, clay, and carbonate of mag- 
 nesia. The clay plays an important part in giving hy- 
 draulicity to the lime, consequently this power is great- 
 er in proportion to the amount of clay contained in the 
 lime. The proportion of clay varies from 10 to 30 per 
 cent. When lime contains clay it is not so easily slaked 
 as pure lime, and does not expand so much in doing 
 so, and therefore does not shrink so much in setting. 
 
 Lias lime (called blue lias from the color of the stone 
 from which it is produced) is very variable in quality 
 and is generally of a feeble nature, but is sometimes of 
 an hydraulic nature. M. Vicat divides them into three 
 classes: feebly hydraulic, ordinary hydraulic, and emi- 
 nently hydraulic. Those belonging to the first class 
 contain from 5 to 12 per cent, of clay. The slaking 
 action is accompanied by cracking and heat. They also 
 expand considerably, and greatly resemble the fat limes 
 during this process. They are generally of a buff color. 
 Those of the second class contain from 15 to 20 per 
 cent, of clay. They slake very sluggishly in an hour 
 or so without much cracking or heat, and expand very 
 little. They set firmly in a week. The eminently hy- 
 draulic limes contain from 20 to 30 per cent, of clay, 
 are very difficult to slake, and only do so after a long 
 time. Very frequently they do not slake at all, being 
 reduced to a powder by grinding. They set firmly in 
 a few hours, and are very hard in a month." 
 
PLASTER, LIME, ETC. 
 
 67 
 
 A natural hydraulic lime is obtained from what ap- 
 pears to be a sedimentary limestone that has been 
 formed by being deposited from water which held it in 
 solution. It is very fine-grained, and contains almost 
 no fossils, and scarcely the trace of a shell is to be seen, 
 except at the top and bottoms of the divisions, which 
 are four in number, and in all from 9 to 12 ft. thick. 
 "When first worked, the stone was slaked in hot kilns, 
 but now this is effected by grinding. According to the 
 '^M'Ara" process, the '^lime shells" from the kiln are 
 ground in the same way as the clinker of Portland ce- 
 ment. Beginning with a stone-breaker, the lime passes 
 from this to a pair of chilled crushing rollers, and final- 
 ly to the millstones, after which the powder is carried 
 by sere v-conveyor and elevator to a rotary screen, 12 ft. 
 by 4 feet, covered with wire cloth, which retains and 
 returns to the millstones any residue in excess of the 
 required fineness. Sifting is a very important factor in 
 the process, as it is scarcely possible to have the mill- 
 stones so perfect that they will not pass a few large 
 particles. 
 
 The residue of imperfectly ground lime will doubt- 
 less slake when mixed with water, but at long or un- 
 certain periods, so that it is obvious that fine grinding 
 is a necessity, and the setting properties are not fully 
 and safely developed unless the whole is finely pulver- 
 ized. With regard to ^^Fat lime": the general prac- 
 tice is for lime producers to show their lime as rich as 
 possible by analysis, and for users to prefer a rich lime, 
 for the reason that it makes a more plastic and better 
 working mortar with the usual quantity of sand. Now, 
 it has been proved by experiments, many and varied, 
 and extending over a long period, by the most eminent 
 authorities, French, German, English and American, 
 
68 CEMENTS AND CONCRETES 
 
 that this preference should exactly be reversed, and 
 that the poorer common limes will make the best mor- 
 tar, and will, in a comparatively short time, show some 
 light setting power, whereas the very rich limes never 
 take band, except in so far as they return to their orig- 
 inal condition of carbonate by the reabsorption of car- 
 bonic acid from the atmosphere, and by the slow evap- 
 oration of the water of mixture. If it does not evapo- 
 rate, the mortar remains always soft. If it evaporates 
 too quickly, the mortar falls to powder, a result which 
 must be in every one's experience who has witnessed 
 the taking down of old buildings, and the clouds of 
 dust created by the removal of every stone. 
 
 Some of the stones from which fat lime is produced 
 contain a portion of sand as an impurity. They there- 
 fore yield an inferior substance. This, though cheaper, 
 is not so economical as pure lime, as it does not increase 
 its volume so much when slaked. The pure or^fat lime 
 should only be used for plastering, as it is easily slaked, 
 and therefore not so liable to blister as most hydraulic 
 limes. It expands to double its bulk when slaked, and 
 can be left and reworked again and again without in- 
 juring it. 
 
 The Romans are said to have prepared their limes. 
 This ^4ime putty,'' prepared by immersion for a longer 
 or shorter period — seldom less than three weeks — before 
 being used, is laid on in a very thin coat, and gives 
 a hard skin to the surface. This hardness is largely, if 
 not wholly, due to the fact that the lime is laid on in 
 a thin layer on the floating coat that has already ab- 
 sorbed carbonic acid from the air„ This thin layer be- 
 comes harder than the main body of tke plaster. 
 
 The whole process of preparing lime and layiixg J 
 on the walls in thin coats, with a considerable space o? 
 
PLASTER, LIME, ETC. 
 
 69 
 
 time between the coating, is conducive to the ultimate 
 hardness of the whole. The lime is first slaked, and 
 then made into coarse stuff, and setting stuff, all this 
 t'me being exposed to the carbonic acid of the atmos- 
 phere. Again, each coat is lang exposed to the same 
 iijfluence before being covered with the next, although 
 in marked contrast to the system of using the mortar 
 in building. 
 
 Calcination. — The process of ^4ime burning" is car- 
 ried out in several different ways. But whether the 
 operation be carried out in the simplest manner, or in 
 kilns constructed on the most scientific principles, it 
 will still depend (both as regards the quality and quan- 
 tity of lime produced) upon the kilnsman, as it is only 
 by constant observation from day to day that the man 
 becomes capable of judging whether the proper ttm- / 
 perature has been reached or that a correct opinion 
 can be formed as to the effects produced by the various 
 disturbing causes which exert an important influence 
 upon the working of a kiln, such as its size, shape, the 
 quality of the fuel, and the state of the atm.osphere. 
 The kilns vary in size and shape in different districts, 
 though they are generally inverted cones or ellipsoids, 
 into which layers of limestone and fuel are alternately 
 thrown. When worked continuously as running kilns, 
 the lime is periodically withdrawn from below, fresh 
 quantities of fuel and stone being filled in at the top. 
 When lime has not been properly calcined, or ^^dead 
 burnt," it will not slake with water. This may arise 
 from two causes — from insufficient burning, when the 
 limestone, instead of being entirely caustified, has only 
 been changed into a basic carbonate, consisting of two 
 equivalents of lime and one of carbonic acid, one-half 
 only of its carbonic acid having been expelled. This 
 
70 
 
 CEMENTS AND CONCRETES 
 
 basic carbonate, on the addition of water, instead of 
 forming a hydrate of lime, and being converted into 
 a fine and impalpable powder, attended with the pro- 
 duction of a large amount of heat, is changed, with 
 little elevation of temperature, into a mixture of hy- 
 drate and carbonate. In the case of hydraulic limes 
 which contain a considerable amount of silica, this 
 ^'dead burning'' may arise from the limestone having 
 been subjected to a too high temperature, whereby a 
 partial fusion of the silicate of lime formed has been 
 produced, giving an impervious coating to the inner 
 portions of the stone, retarding the further evolution 
 of the carbonic acid. On this account the eminently 
 hydraulic limes require to be carefully calcined at as 
 low a temperature as practicable ; and hence it is not 
 infrequently found that lias lime has been imperfectly 
 calcined. Pure limes, if subjected to an excessive 
 temperature, exhibit somewhat less tendency to com- 
 bine with water than is the case with lime properly 
 calcined. Caustic limes unite with water with great 
 energy, so much so as to evolve a very considerable 
 amount of heat. When water is poured upon a piece 
 of well-burnt lime heat is rapidly generated, and the 
 lime breaks up with a hissing, crackling noise, the 
 whole mass being converted in a short time into a soft, 
 impalpable powder, known as slaked lime." 
 
 Slahing. — Chemically speaking slaked lime is hydrate 
 of lime — that is, lime chemically combined with a 
 definite amount of water. In the process termed '^slak- 
 ing'' one equivalent or combining proportion of lime 
 unites with one equivalent of water, or in actual weight 
 28 lbs. of lime combines with 91 lbs. of water (being 
 nearly in the proportion of three to one) to form 37 
 lbs. of solid hydrate of lime. The water loses its liquid 
 
PLASTER, LIME, ETC. 
 
 71 
 
 condition, and it is to this solidification of water that 
 the heat developed during- the process of slaking is 
 partly due. 
 
 Slaking is a most important part in the process of 
 making coarse stuff and putty lime. Unless the slak- 
 ing is carefully and thoroughly done, the resultant ma- 
 terials are liable to blister'^ or ^'blow," owing to 
 small particles still remaining in a caustic state. Blis- 
 ters may not show until a considerable time has 
 elapsed. There are three methods of slaking ^'lump- 
 lime" — the first by immersion; the second by sprint- 
 ling with water; and the third by allowing the lime to 
 slake by absorbing the moisture of the atmosphere. 
 Rich limes are capable of being slaked by immersion, 
 and kept in a plastic state. They gain in strength by 
 being kept under cover or water. Pliny states that the 
 Romans had such great faith in this method that the 
 ancient laws forbade the use of lime unless it had been 
 kept for three years. All rich limes may be slaked 
 by mixing with a sufficient quantity of water, so as to 
 reduce the whole to a thick paste. Lump lim.e should 
 first be broken into small pieces, placed in layers of 
 about six inches thick, and uniformly sprinkled with 
 water through a pipe having a rose on one end, or by 
 means of a large watering-can having also a rose, and 
 covered quickly with sand. It should be left in this 
 state for at least twenty-four hours before being turned 
 over and passed through a riddle. The layer of sand 
 retains the heat developed, and enables the process of 
 slaking to be carried out slowly throughout the miass. 
 Any unslaked lumps may be put into the middle of the 
 next heap to be slaked. The quantity of water should 
 be perfectly regulated, as if over-watered a useless paste 
 is formed. If a sufficient quantity is not supplied, ^ 
 
72 CEMENTS AND CONCRETES 
 
 dangerous powdering lime* is produced. Slaking by 
 sprinkling and covering the lime lumps is frequently 
 done in a very imperfect and partial manner, and por- 
 tions of the lime continue to slake long after the mortar 
 has been used. Special care must . be exercised, and 
 sufficient time must be allowed for the lime to slake 
 when this method is employed. 
 
 Different qualities of lime require variable amounts 
 of water; but the medium quantity is about a gallon 
 and a half to every bushel of lime. No water should 
 be added or the mass disturbed after slaking has be- 
 gun. In most places the lime for making coarse st'uff 
 is generally slaked by immersion, and is run into 
 a pit, the sides of which are usually made up with 
 boards, brick work, or sand, the lime being put into 
 a large tub containing water. When the lime is slaked, 
 it is lifted out by means of a pail, and poured through 
 a coarse sieve. It is sometimes made in a large oblong 
 box, having a movable or sliding grating at one end to 
 allow the lime to run out and also to prevent the sedi- 
 ment from passing through. 
 
 In preparing lime for plaster work, the general prac- 
 tice is to slake it for three weeks before using. Not 
 only so, but a particular cool lime is selected, for the 
 reason that it is not liable to blister and deface the 
 internal walls when finished. Now, while all this pre- 
 caution is taken in regard to plastering, in making mor- 
 tar for building the lime is slaked and made up at 
 once, and it is frequently -used within a day or two. 
 But this is not all. Limes which are unsuitable for 
 plaster work, known as hot limes, and which, when 
 plasterers are obliged to use^ must be slaked for a 
 period of — not three weeks, but more — nearly three 
 months before using, and are then not quite safe from 
 
PLASTER, LIME, ETC. 
 
 73 
 
 blistering, are the limes mostly used for building pur- 
 poses. It will at once be seen that when mortars of 
 these limes are used immediately, the unslaked par- 
 ticles go on slaking for a long time, drying up the 
 moisture, and leaving only a friable dust in the joints. 
 This should help in understanding the old Roman law 
 which enacted that lime should be slaked for three 
 years before using. If three years should seem to us 
 an absurd time, yet it may be justly said that at least' 
 three months are required to slake completely, and to 
 develop fully the qualities of many of the common 
 limes in everyday use. Major-General Gillmore, the 
 eminent American specialist on the subject of Limes 
 and Cement, mentions that in the south of Europe it 
 is the custom to slake the lime the season before it is 
 to be used. 
 
 Mortar. — This is a term used for various admixtures 
 of lime or cement, with or without sand. For plaster 
 work it is usually composed of slaked lime, mixed with 
 sand and hair, and is termed coarse stuff," and some- 
 times ''lime and hair," also ''lime." In Scotland the 
 coarse stuff is generally obtained by slaking the lump 
 lime (locally termed shells) with a combination of 
 water sprinkling and absorption. The lime is placed in 
 a ring of sand, in the proportion of one of lime to 
 three of sand, and water is then thrown on in suffi- 
 cient quantities to slake the greater portion. The whole 
 is then covered up with the sand, and allowed to stand 
 for a day; then turned over, and allowed to stand for 
 another day; afterwards it is put through a riddle to 
 free it from lumps, and allowed to stand for six weeks 
 (sometimes more) to further slake by absorption. It 
 is next "soured" — that is, mixed with hair ready for 
 use. Sometimes when soured the stuff' is made up in 
 
74 CEMENTS AND CONCRETES 
 
 a large heap, and worked up again as required for 
 use. This method makes a sound, reliable mortar. In 
 some parts lime slaked as above is mixed with an equal 
 part of run lime. This latter method makes the coarse 
 stuff fatter'^ and works freer. All slaked limes have 
 a greater affinity for water than the mechanically 
 ground limes. 
 
 Grinding is another process for making mortar or 
 ^ ^ lime, ' ' and if made with any kind of limestone is 
 beneficial. It thoroughly mixes the material, increases 
 the adhesion, adds to the density, and prevents blister- 
 ing. When there is a mortar-mill, either ground or 
 lump lime can be used, and the coarse stuff may be 
 made in the proportion of 1 part lime and 3 parts 
 sand. The lime should be left in the mill until thor- 
 oughly reduced and incorporated, but excessive grind- 
 ing is detrimental The process should not be con- 
 tinued more than thirty minutes. Both mxaterial and 
 strength is economized if lump lime is slaked before 
 being put in the mill. 
 
 When a mortar-mill is used for grinding the lime, 
 the sand may be partly or wholly dispensed with, and 
 excellent results are obtained by using old broken bricks 
 (clean and well burnt), stone chippings, furnace cin- 
 ders (free from coal), or slag. It is most essential in 
 all cases that the materials used should be perfectly 
 clean. It should be "Borne in mind that a complete in- 
 corporation of the ingredients is essential in the slak- 
 ing and mixing for coarse stuff, whether done by hand 
 or machine. The sand or other material used can be 
 tested by washing a portion in a basin of clean water, 
 then sifting through a fine sieve. If there is an undue 
 residue of clay, fine dust or mud in the water or sieve, 
 the whole of the aggregate should be washed or re- 
 
PLASTER, LIME, ETC. 
 
 75 
 
 jected. Lias lime should be mixed dry with sand and 
 damped down for seven or ten days to ensure slaking. 
 It should not be used fresh for floating or rendering-. 
 Pure or rich limes are not so well adapted for outside 
 work, or places exposed to the action of damp, as hy- 
 draulic limes. Mortar should be well tempered before 
 using. Pliny states that it was an ancient practice to 
 beat the mortar for a long time with a heavy pestle 
 just before being used, the effect of which would be 
 not only more thoroughly to mix the materials, but to 
 take from the outside of the sand the compound of 
 lime and silica (if such had been formed during the 
 period of seasoning) and by incorporating it with the 
 mass, dispose it more rapidly to consolidate. Smeaton 
 found that well-beaten mortar set sooner and became 
 harder than mortar made in the usual way. Mortar 
 made from hydraulic limes should be mixed as rapidly 
 as is compatible with the thorough incorporation of the 
 materials, and used as soon as practicable after mixing, 
 because if put aside for any length of time its setting 
 properties will deteriorate. 
 
 Pure limes may be rendered hydraulic by mixing 
 them with calcareous clays or shales, which have been 
 so altered by the agency of heat that the silica they con- 
 tain has to some extent assumed the nature of soluble 
 silica. In good coarse stuff each granule of sand is 
 coated over with the lime-paste so as to fill the inter- 
 stices; the lime-paster is to hold the granular sub- 
 stances in a concrete form. If too much lime-plaster 
 is present, it is called ''too fat"; if the lime-paster is 
 deficient it is ''too lean'' or "poor." This can be 
 tested by taking up a portion on a trowel; the "fat" 
 will cling to the trowel while the "lean" will run off 
 like wet sand. The coarse stuff can be tested by mak- 
 
76 CEMENTS AND CONCRETES 
 
 ing briquettes and slowly drying; the good will stand 
 a great pressure, whereas the bad will not — in some 
 cases falling to pieces. Some coarse stuff will appear 
 ^^fat" on the trowel^ but it may be the fatness of mud, 
 not the fatness of lime^ because sometimes sand is 
 adulterated with fine-screened earth. When this stuff 
 is made in the form of briquettes and dried, it will be 
 extremely friable and easy to crush; or if put into 
 water until soft, the earthy matter can be seen. Fine- 
 screened earth, when dry and in bulk, does not seem 
 an objectionable material; but in a wet state it is dirt 
 or mud, and should at once be sent off to the works. 
 All limes increase in strength by the addition of sand, 
 being the reverse of Portland cement, which is weak- 
 ened by this addition. Mr. Read made four samples 
 of mortar with the proportions of ground lime and sand 
 as follows : ' ' Ground lime mixed with 4, G, 8 and 10 
 parts of clean washed sand to 1 part of ground lime 
 respectively. All set and went hard. One of each 
 was placed in water; that made with 4 parts of sand 
 expanded and went to pieces; those with 6, 8 and 10 
 parts of sand remained whole, and continued to get 
 harder." The addition of a small proportion of brick 
 dust to mortar will harden and prevent the disinte- 
 gration of mortar. The proportions are 1 part of brick 
 dust, 2 parts of sand and 1 part of lime, mixed dry 
 and tempered in the usual way. 
 
 Adhesive Strength. — The adhesive strength of mortar 
 varies according to the amount of sand used. The 
 more sand used in the mortar, the less its adhesion. 
 The following table shows the force required to tear 
 apart bricks bedded in mortar made with the usual 
 proportions of sand at the end of twenty-eight days : 
 
PLASTER, LIME, ETC. 77 
 Adhesive Strengths of Limes and Cements. 
 
 Fat lime and sand 
 Common lias lime and sand 
 
 Portland cement 
 
 <{ a (t (t 
 
 The old mortar which was held in such high esteem- 
 by the Romans is said to have consisted of lime mixed 
 w^ith puzzolana or trass. Trass is a material similar 
 in its nature to puzzolana, obtained from extinct vol- 
 canoes in the valley of the Rhine, also in Holland, and 
 is largely employed in engineering works. The name 
 trass is derived from a Dutch word meaning a binding 
 substance. Much has been written and said about the 
 ancient and the old Roman mortars, but it may be 
 safely said that, from the year one up to the present 
 time, no cement or mortar has the strength, or could 
 excel, or stand our variable climate as well as Portland 
 cement. The primary cause of the premature decay 
 which takes place in stuccos and cements, when used 
 externally as a coating to walls, is the presence of 
 muddy earth and decayed animal and vegetable matter 
 in the sand used in the lime and cement. To this may 
 be added the frequent impurities in the limes and ce- 
 ment themselves. The impurities in the sand may be 
 eradicated by a thorough washing, and the lime should 
 be carefully selected, prepared and manipulated. Hav- 
 ing now briefly reviewed the principal parts and 
 process of mortar, the practical, conclusions to be 
 drawn are, that the quality of the lime is of as great 
 importance as the quantity, and thorough slaking is 
 imperative ; that the proportions of sand may vary con- 
 
 (1 to 3) 4% lbs. per Sq. In. 
 
 il Q (( (( U << 
 
 (lto4) 6% " " " " 
 
 (lto4) 23 " " " " 
 
 (lto6) 15X " " " 
 
78 
 
 CEMENTS AND CONCRETES 
 
 siderably, and that it should be coarse and irregular in 
 size, and of a clean and hard nature. 
 
 The Hardening of Mortar. — According to the results 
 obtained from tests and experience, the hardening of 
 mortar is due to several causes acting collectively. 
 These causes appear to be absorption of carbonic acid 
 from the atmosphere, and the combination of part of 
 the water with the lime which act upon the sand, dis- 
 solve and unite with some of the silica of the sand is 
 composed, thus forming a calcium silicate (silicate of 
 lime). Some authorities state that the silicate of lime 
 is formed by the reaction of lime and silicate of mor- 
 tar, and to this is due the hardness of old mortar. In 
 mortar from the pure lime, the initial setting is due 
 to the evaporation of water, and to the production of 
 minute crystals of hydrate of lime, which slowly ab- 
 sorbs carbonic gas from the air, the rapidity of this 
 absorption necessarily decreasing in proportion to the 
 difficulties presented to the free access of air. The 
 setting and hardening of hydraulic limes are due mainly 
 to crystallization brought by the action of water on 
 the silicate of lime and not mere absorption of carbonic 
 gas from the atmosphere, as is the case of fat limes. 
 
 The Romans were convinced that it was owing to 
 prolonged and thorough slaking that their works be- 
 came so hard, and were not defaced by cracks. Al- 
 berti mentions that he once discovered in an old trough 
 some lime which had been left there five hundred 
 years, as he was led to believe by many indications 
 around it, and that the lime was as soft and as fit to 
 be used as if it had been recently made. Common mor- 
 tar made of rich lime hardens very slowly, and only 
 by the evaporation of the water of the mixture, and by 
 the absorption of carbonic acid from the atmosphere, 
 
PLASTER, LIME, ETC. 
 
 79 
 
 with which it forms a crystalline carbonate of lime. 
 This process, however, is so slow, that it gave rise to 
 the French proverb that ''Lime at a hundred years old 
 is still a baby''; and there is a similar proverb among 
 Scotch masons, ''When a hundred years are past and 
 gane, then gude mortar turns into stane. '' Mortar 
 from the interior of the pyramids, where it has been ex- 
 posed to the action of the air, still contains free lime, 
 although it is five thousand years old. It has been 
 ascertained that in rich lime mortars the carbonic acid 
 penetrates about one-tenth of an inch into the joint in 
 the first year, forming a skin or film which opposes the 
 further absorption of carbonic acid, except at a decreas- 
 ing ratio, so that the lime remains soft for an indefi- 
 nite period. In illustration of this several cases have 
 been cited, amongst others one by General Treussart, 
 who, in the year 1822, had occasion to remove one of 
 the bastions erected by Vauban in 1666. After ihese 156 
 years the lime in the interior was found to be quite 
 soft. Dr. John, of Berlin, mentions that in removing 
 a pillar of 9 ft. diameter in the Church of Saint Peter, 
 Berlin, eighty years after erection, the mortar was found 
 to be quite soft in the interior. 
 
 General Pasley mentions several instances at Dover 
 Harbor, and at Chatham dock yard, the latter in par- 
 ticular, when part of the old wall was pulled down in 
 the winter of 1834. The workmen were obliged to blast 
 the brickwork fronting the river, which had been built 
 with Roman cement, but the backing, done with common 
 lime mortar, was in a state of pulp; the lime used had 
 been prepared from pure limestone or chalk. But it 
 is unnecessary to go back so far for knowledge of the 
 absence of the setting quality in the rich limes, as 
 there have been frequent experiences of it in the pres- 
 
80 
 
 CEMENTS AND CONCRETES 
 
 ent age. While these remarks are true of the richer 
 limes, many of our limes are comparatively poor in 
 carbonate, and associated with silica, alumina, mag- 
 nesia and oxide of iron, which may either be partially 
 combined in the natural state, or enter into combina- 
 tion with the lime during the process of calcination, 
 and these limes might be termed slightly hydraulic. 
 
 M. Landrin, who submitted to the French Academy 
 the results of some experiments on the hydraulicity and 
 hardening of cements and lime, came to the conclusion 
 that (1) silicates of lime raised to high temperature 
 set with difficulty, and in any case do not harden in 
 water; (2) for the recalcination of cements to exert 
 a maximum influence on the setting, in connection with 
 water of the compound obtained, the process must be 
 carried sufficiently far for the limes to act on the silica 
 so as to transform it into hydraulic, and not fused 
 silica; and (3) carbonic acid is an indispensable factor 
 in the setting of siliceous cements, in as much as it is 
 this substance which ultimately brings about their hard- 
 ening. The comparative strengths of various mortars 
 are shown in the following table: 
 
PLASTER,^ LIME, 
 
 ETC. 
 
 81 
 
 a; a; 
 
 is 
 
 ^ a 
 
 li 
 
 si 
 
 a; 
 
 be 
 
 <+-( W 
 
 a: 
 
 dj o3 
 
 . o o o 
 
 • +J +J ^ 
 
 • o ic ^ 
 
 • 00 00 
 
 odd 
 
 o o o o o o 
 
 ^ 4-» -M +J 
 
 T-i o o o o ^ 
 
 00 00 CO O CD tH 
 tH tH tH tH 
 
 0 0 0 
 
 5c <U o 
 C O. • 
 
 ^ Kr, 
 
 tH <u rJ.rH 
 
 05 O CO J> ^ ^ 
 
 i> 00 rH TdH CO 
 
 J>i> CO coooocoooo^ 
 (M CO O CO iO J> IC 
 
 o CO CO 
 
 00 TtH CO 
 
 cogs 
 m «3 « 
 
 CO 
 
 o o 
 
 T-5 d 
 CO o 
 
 CO O 00 tH <M i:^ 
 lO 00 00 CO CO (M 
 
 co' tJH i6 ci no 
 
 CO lO rH CO CO 05 
 (M T-H tH rH T— ( 
 
 CO CO 
 
 CO 00 CO 
 
 
 ater. 
 
 CO CO 
 CO CO 
 
 CO 
 CO 
 
 iO CO o o o o 
 
 05 CO O IC O lO 
 
 
 O CO o 
 O CO o 
 
 
 
 rH rH 
 
 1—1 
 
 T-H rH <M* tH (M* 05 
 
 
 rH* rH 05 
 
 noNS. 
 
 Lime. 
 
 1.00 
 1.00 
 
 1.00 
 
 . . . o CO CO 
 . . . io CO 00 
 
 • • • d d d 
 
 Loam. 
 0.50 
 0.66 
 0.83 
 
 
 
 
 
 
 
 
 ment 
 
 
 
 o o o o o o 
 o o o o o o 
 
 
 o o o 
 o o o 
 
 
 O 
 
 
 
 rH rH tH tH T-i rH 
 
 
 rH rH rH 
 
 
 'd 
 c 
 
 o o 
 o o 
 
 o 
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 o o o o o o 
 o o o o o o 
 
 
 O O O 
 
 o o o 
 
 
 c3 
 
 
 05 
 
 d oo' d d 00 d 
 
 rH tH 
 
 
 d 00 d 
 
 rH 
 
 t> i> iC Q iC O lO 
 tH 05 05 rH 05 CO i> i> 00 
 
 rH JO Oi 
 05 05 tH 
 
 tH 05 CO rH 05 CO tH C5 CO 
 
82 
 
 CEMENTS AND CONCRETES 
 
 Magnesia in 'Mortars. — Magnesia plays an important 
 part in the ''setting'' of hydraulic limes as well as in 
 Portland cement. Vicat, after many experiments, was 
 led to recommend magnesia as a suitable ingredient of 
 mortars to be immersed in the sea, stating that if it 
 could be obtained at a cost that would admit its appli- 
 cation to such purposes, the problem of making con- 
 crete unalterable by sea water would be solved. Gen- 
 eral Gillmore, speaking of the American lime and ce- 
 ment deposits, says: ''Magnesia plays an important 
 part in the 'setting' of mortars, derived from the ar- 
 gillo-magnesian limestone such as those which furnish 
 the Rosendale cements. The magnesia, like the lime, 
 appears in the form of a carbonate. During calcination 
 the carbonic acid is driven off, leaving protoxide of 
 magnesia which comports itself like lime in the pres- 
 ence of silica and alumina, by forming silicate of mag- 
 nesia and aluminate of magnesia. These compounds 
 become hydrated in the presence of water, and are 
 pronounced by Vicat and Chatoney to furnish gangues, 
 which resist the dissolving action of sea water better 
 than the silicate and aluminate of lime.. This statement 
 is doubtless correct, for we know that all of these com- 
 pounds, whether in air or water, absorb carbonic acid, 
 and pass to the condition of subcarbonates, and that 
 the carbonate of lime is more soluble in water holding 
 carbonic acid and certain organic acids of the soil in 
 solution than the carbonate of magnesia. At all events, 
 whatever may be the cause of the superiority, it is 
 pretty well established by experience that the cements 
 derived from argillo-magnesian limestones furnish a 
 durable cement for construction in the sea." 
 
 In Marshal VaiUant's report to the French Academy 
 of Sciences, from the Commission to which Chatoney 
 
PLASTER, LIME, ETC. 
 
 83 
 
 and Rivot's paper was referred in 1856, this superiority 
 of the magnesian hydrates is distinctly asserted. A few 
 years ago the French Government Office of Civil En- 
 gineers made a series of comparative tests on three sam- 
 ples each of French, English and German cement, in 
 which the results are given in favor of the German 
 cement, which contains magnesia to the extent of 2.4 
 per cent, against 0.26 in the English and 0.32 in the 
 French, and summed up thus: ^^A great value partly 
 due to the higher percentage of magnesia contained in 
 it." Gillmore further says that magnesian limestone 
 furnishes nearly all the hydraulic cement manufactured 
 in the western part of the State of New York. At 
 East Vienna it has been used for cement, and at Akron, 
 Erie County, N. Y., a manufactory of some extent is in 
 operation. Vicat says: Having analyzed several old 
 mortars, with the view of discovering, if possible, to 
 what their superior durability might be attributed, I 
 found, in some excellent specimens of very old mortar, 
 magnesia to exist in considerable proportions." The 
 limestones, therefore, from which these mortars were 
 prepared must have contained the silica and magnesia 
 as constituent ingredients; and it is to be remembered 
 that it is the presence of these substances which com- 
 municates the property of hardening under water. Pro- 
 fessor Scorgie says of carbonate of magnesia: ^^Mag- 
 nesium carbonate is a substance very similar to carbon- 
 ate of lime; it loses its carbonic acid in burning, com- 
 bines with silica, etc., and behaves generally in the 
 same way ; it does not slake, however, on being wetted, 
 but combines with the water gradually and quietly sets 
 to some extent in doing so. Magnesium carbonate com- 
 bined with lime, reduces the energy of slaking, and in- 
 creases that of the 'setting' process; when other sub- 
 
84 CEMENTS AND CONCRETES 
 
 stances are present, its behavior and combination with 
 them are similar to those of lime. When carbonate of 
 magnesia is present in sufficient quantity, say about 30 
 per cent., it renders lime hydraulic independently of 
 and in the absence of clay.'' Colonel Pasley also, by 
 experiments, demonstrated that magnesium limestones 
 are suitable for hydraulic mortars. 
 
 The foregoing assertions that magnesium carbonate,, 
 combined with lime, reduces the energy of slaking and 
 increases that of the ^Ssetting'' processes are satisfac- 
 tory and conclusive. Many such evidences showing the 
 value of magnesia in hydraulic mortars might be quoted, 
 but perhaps these are sufficient. 
 
 Effects of Salt and Frost in Mortar. — Few experi- 
 ments have as yet been made to test the general effects 
 of salt in mortars, though as a preventive of the effects 
 of frost it has been tried with varying results. 
 
 In some experiments, designed to ascertain the effect 
 of frost upon hydraulic limes and cement gauged with 
 and without addition of salt to the water, cubes of stone 
 were joined together with cement mixed with water 
 ranging from pure rainwater to water containing from 
 2 to 8 per cent, of salt. Before the cement was set the 
 blocks were exposed in air at a temperature varying 
 from 20 to 32 degrees Fahr., after which they were 
 kept for seven days in a warm room. At the end of 
 this time the samples were examined. The cement 
 made with water was quite crumbled, and had lost all its 
 tenacity. The cement made with water containing 2 per 
 cent, was in better condition, but could not be described 
 as good ; while that containing 8 per cent, of salt had not 
 suffered from its exposure to the lowest temperature 
 available for the purpose of experiment. It is suggested 
 as possible that the effect of the salt was merely to pre- 
 
PLASTER, LIME, ETC. 
 
 85 
 
 vent the water in which it was dissolved from freezing at 
 the temperature named, and so permitted the cement 
 to set in the ordinary way. But it must be allowed 
 that in practice, salt dissolved in the water for mixing 
 mortar has been successfully used to resist the effect 
 of frost. A solution of salt applied to new plastered 
 walls in the event of a sudden frost will protect the 
 work from injury. The addition of a small portion 
 of sugar will improve its adhesion, and increase the 
 frost-resisting powers. 
 
 Salt takes up the vapors from the atmosphere, caus- 
 ing the work to show efflorescence, and in some instances 
 to flake, especially in external work. That some en- 
 gineers believe there is virtue in salt water is beyond 
 doubt, because salt water has been named in their speci- 
 fications for the gauging of concrete. Salt in Portland 
 cement seems to act somewhat differently; as regards 
 efflorescence it shows more in this material than in lime 
 mortar. Salt should not be used in Portland cement 
 work that has to be subsequently painted. According to 
 the results of tests of mortar used for the exterior 
 brick facing of the Forth Bridge piers below water they 
 show a good average tensile strength. One part of 
 Portland cement and one part of sand were slightly 
 ground together in a mill with salt water, and briquettes 
 made from this gauge gave an average of 365 lbs. per 
 square inch at one week, and 510 lbs. at five weeks after 
 gauging. It would be interesting to note the condition 
 of this mortar a century hence, time being the trying 
 test for all mortars. 
 
 A solution of commercial glycerine mixed with the 
 setting stuff, or used as a wash on newly finished lime 
 plaster work, is a good preventive of the evil effects of 
 frost. Glycerine solution may also be used for the same 
 
86 CEMENTS AND CONCRETES 
 
 purpose on new concrete paving. Strong sugar water 
 mixed with coarse stuff has some power in resisting 
 frost. The quantity depends upon the class of lime, 
 but the average is about 8 lbs. of sugar to 1 cubic yard 
 of coarse stuff or setting stuff. The sugar must be dis- 
 solved in hot water and the stuff used as stiff' as pos- 
 sible. 
 
 Sugar With Cement, — Sugar or other saccharine mat- 
 ter mixed with cement has been tried with varying 
 success. It is well known that saccharine is used with 
 mortars in India. According to some experiments made 
 in this country, the results obtained were that the addi- 
 tion of sugar or molasses delayed the setting of the 
 mortar, the retardation being greater when molasses was 
 used. When certain proportions were not exceeded, the 
 strength of the mixture was that of the pure cement. 
 Less than 2 per cent, of sugar must be added to Port- 
 land cement, and less than 1 per cent, to Roman, other- 
 wise the mortar will not hold together. The sugar ap- 
 pears to have no chemical action on the other materials, 
 crystals of it being easily detected on the broken sur- 
 faces, the increased binding power of the cement 
 brought about by the addition of sugar being due more 
 to mechanical than chemical causes. In my own experi- 
 ments with sugar added to Portland cement for cast- 
 ing deep undercut ornament figures and animals out 
 of gelatine moulds, the results at first were very irregu- 
 lar, some casts attaining great hardness, while others 
 crumbled to pieces. The time of setting also varied 
 considerably. Three different brands of cement were 
 used, and it was found that the cement containing the 
 most lime required more sugar than the lowest limed 
 cement, but the average is about II/2 per cent, of added 
 sugar. The sugar must be dissolved in the water used 
 
PLASTER, LIME, ETC. 
 
 87 
 
 for gauging. The setting and ultimate hardness is also 
 influenced by the atmosphere. The casts should be kept 
 in a dry place until set and dry, before exposing them 
 to damp or wet. Portland cement has a tendency (es- 
 pecially if over limed) to *'fur" gelatine moulds, but 
 the sugared cement leaves the moulds quite clean. 
 
 In experiments by Austrian plasterers, mixtures of 
 1 part of cement and 3 parts sand, and 10 per cent, of 
 water, and of pure cement with as much water as was 
 necessary to give the mass plasticity, were prepared. 
 From 1 to 5 per cent, of powdered sugar was well mixed 
 with the dry cement. The cement used was of inferior 
 quality, the sand being ordinary building sand, and 
 not the so-called ^'normaP' sand, which is of a superior 
 quality. They were left to harden in a dry place, and 
 not under water. For each series of samples made with 
 sugar a comparative series without sugar was prepared, 
 all the samples being made by the same man, under the 
 same conditions and with the same care. The tenacity 
 was ascertained by Kraft's cement-testing machine. The 
 strength was far below that prescribed and generally 
 obtained. It should be mentioned that the samples with 
 sugar (especially those of pure cement) showed a strong 
 tendency during the first twenty-four hours to combine 
 intimately with the smooth china plate on which they 
 were placed to swell, and the results of the trial showed 
 that with mixtures of cement and sand, and by harden- 
 ing in a dry place, the binding effect may be increased 
 by the addition of sugar, which reached its maximum 
 with from 3 to 4 per cent, of sugar added. With pure 
 cement the binding effect was not much increased. If 
 the sugar used for gauging had been dissolved, and not 
 mixed dry, the results would have proved better. 
 
88 CEMENTS AND CONCRETES 
 
 Sugar in Mortar. — Most writers have supposed that 
 the ''Old Eoman Mortars'' contained strong ale, wort, 
 or other saccharine matter, and it is probable that the 
 use of sugar with lime passed from India to Egypt and 
 Rome, and that malt or other saccharine matter was 
 used in their mortars. The addition of sugar to water 
 enables it to take up about 14 times more lime than water 
 by itself. The following is an extract from the Roorkee : 
 ' ' It is common in this country to mix a small quantity of 
 the coarsest sugar, 'goor,' or 'Jaghery,' as it is termed 
 in India, with the water used for mixing up mortar. 
 Where fat limes alone can be produced their bad quali- 
 ties may in some degree be corrected by it, as its influence 
 is very great in the first solidification of mortar. This is 
 attributed to the fact that mortars made of shell lime 
 have stood the action of the weather for centuries owing 
 to this mixture of Jaghery in their composition. Experi- 
 ments were made on bricks, joined together by mortar 
 consisting of 1 part of common shell lime to 1^2 of sand, 
 1 lb. of Jaghery being mixed with each gallon of water. 
 The bricks were left for 13 hours, and after that time 
 the average breaking weight of the joints in 20 trails 
 was 61/2 lbs. per square inch. In twenty-one specimens 
 joined with the same mortar, but without the Jaghery, 
 the breaking weight was lbs. per square inch." 
 
 The Madras plasterers make most beautiful plaster 
 work, almost like enamelled tiles, the shell lime being 
 mixed with Jaghery. The surface takes a fine polish 
 and is as hard as marble, but it requires a good deal of 
 patient manipulation. Dr. Compton has made some ex- 
 periments with sugar gauged with cements and mortars, 
 and says, ' ' That in medicine there are two kinds of lime- 
 water, one the common lime-water, that can be got by 
 mixing lime and water, and it is particularly noted 
 
PLASTER, LIME, ETC. 
 
 89 
 
 that, add as much lime as you like, it is impossible to get 
 water to dissolve more than half a grain of lime in one 
 ounce, or about two teaspoonfuls of water. But by add- 
 ing 2 parts of white sugar to 1 part of lime, there is a 
 solution obtained which contains about 14^ times more 
 linie in the same quantity of water. Here it is to be ob- 
 served — and it is a most important point — that there are 
 hot limes, such as Buxton^ which if they be incautiously 
 mixed with them, will burn the sugar, make it a deep 
 brown color, and convert it into other chemical forms, 
 and possibly destroy its value in mortar." 
 
 The Jaghery sugar used in India is sold in the London 
 market at about a penny a pound. Treacle seems to be 
 the most promising form of saccharine matter; beetroot 
 sugar is not good for limes or. cements. There is a rough 
 unrefined treacle which is very cheap, and it is supposed 
 would have an excellent effect. 
 
 Herzf eld states that he used coarse stuff, consisting of 
 1 part of lime to 3 of sand, to which about 2 per cent, 
 of sugar had been added, to plaster some walls in the 
 new building of the Berlin Natural History Museum, 
 and on the day following he found the lime plaster had 
 hardened as if gauged with plaster. He also found it 
 useful in joining bricks, and recommends the coarse stuff 
 to be fresh made, and not with a great proportion of 
 water; and states that good molasses will yield as good 
 results as sugar. 
 
 Lime Putty. — This material is prepared in a similar 
 way to run lime intended for coarse stuff. It is run 
 through a finer sieve into a box or pit. If the latter is 
 used the interior should be plastered with coarse stuff to 
 prevent leakage and keep the putty clean. For good 
 work the best class of lump lime should be used. The 
 putty should be allowed to stand for at least three 
 
90 
 
 CEMENTS AND CONCRETES 
 
 months before it is used. For common work the lump 
 lime for making coarse stuff, putty and setting stuff is 
 often run into one pit. The putty at the end farthest 
 from the sieve, being the finest, is retained for putty and 
 for making setting stuff, and the remainder, or coarser 
 portion, being used for coarse stuff. In many instances 
 the putty is left for months in an unprotected state dur- 
 ing the progress of the building, which is wrong. It may 
 be kept for an indefinite time without injury if protected 
 from the atmosphere, and therefore it should be covered 
 up to resist the action of the air, as it absorbs the car- 
 bonic acid gas and thus becomes slightly carbonated and 
 loses to a certain extent its causticity, and consequently 
 its binding and hardening properties. 
 
 Pliny states that the old Roman limes were kept in cov- 
 ered pits. If a small portion is taken off the top of the 
 putty it will be found not only dry, but scaly, short and 
 inert ; whereas a portion taken from the middle, or up to 
 the part carbonated, will be found to be of an oily and 
 tenacious nature. A cute plasterer always selects the 
 putty furthest from the sieve for mitring purposes, as it 
 is the finest. 
 
 Setting Stuff, — This material is composed of lime 
 putty and washed fine sharp sand. The proportion of 
 sand varies according to the class of lime and kind of 
 work, but the average is 3 parts of sand to 1 of putty. 
 The various proportions are given where required for the 
 different works. Setting stuff is used for finishing coat 
 of lime plastering. It is generally made on a platform, 
 of scaffold boards, and sometimes in a bin. The putty 
 and sand are thoroughly mixed together by aid of a 
 larry. The sand should be sized by washing it through a 
 sieve having a mesh of the desired size. In some districts 
 it is made by pressing or beating the putty and sand 
 
PLASTER, LIME, ETC. 
 
 91 
 
 through a ' ' punching sieve ' ' into a tub. Setting stuff is 
 less liable to shrink and crack, and is improved generally 
 if it is allowed to stand after being made until nearly 
 hard, but not dry, and then ''knocked up" to the re- 
 quired consistency with water (preferably lime-water) 
 and the aid of a shovel and larry. While the stuff is 
 firming by evaporation it should be covered up to protect 
 it from dust and atmospheric influences. It should be 
 used as soon as ''knocked up." Setting stuff may be 
 colored to any desired tint, and also mixed with various 
 ingredients to obtain a brilliant and marble-like surface. 
 
 Haired Putty Setting. — Haired putty was formerly 
 used to a very considerable extent as a setting coat in 
 districts where the local lime was of a strong or hydraulic 
 nature, not very readily manipulated when mixed with 
 sand, as used for setting stuff. This material is com- 
 posed of fine lime putty and well-beaten white hair. The 
 hair was thoroughly mixed with the putty to tougheii 
 and prevent it from cracking. To such an extent was hair 
 ^dded that in some instances the setting coat when 
 broken had the appearance of white felt. This class of 
 setting stuff is now seldom used. 
 
 Lime Water. — This water has many medicinal virtues, 
 and is a simple and inexpensive remedy for cuts and 
 bruises. Plasterers are generally healthy and free from 
 any infectious diseases. This may be partly owing to 
 their almost constant contact with lime. Lime water, 
 used as a wash, will harden plaster casts. It is also used 
 when scouring and trowelling setting stuff to harden the 
 surface. 
 
 Hair. — Hair is used in coarse stuff as a binding me- 
 dium, and gives more cohesion and tenacity. It is usu- 
 ally ox-hair (sometimes adulterated with the short hair 
 of horses). Good hair should be long, strong and free 
 
92 CEMENTS AND CONCRETES 
 
 f rom grease or other impurities. It is generally obtained 
 in a dry state in bags or bundles. This dry hair should 
 be well beaten with two laths to break up the lumps, as, 
 unless the lumps are thoroughly broken so as to sepa- 
 rate the hair they are only a waste, and worse than no 
 hair at all, since the lumps have no binding power and 
 will cause a soft weak spot in the plaster when laid. 
 Many failures of ceilings have been caused by the hair 
 not being properly beaten and mixed. Human hair is 
 sometimes used for jerry work. Goats' hair is often used 
 here. Hair is usually obtained direct from the tanners' 
 yard, fresh and in a wet state. This makes the best 
 work, as it is much stronger and mixes freely. Hair 
 should never be mixed with hot lime, and with no mor- 
 tars until nearly ready for using, because wet or hot 
 lime weakens the hair, more especially if dry. Coarse 
 stuff for first coating on lath work requires more hair 
 than for brick or stone work. When coarse stuff is made 
 in a mill the hair should not be added until the stuff is 
 ground, as excessive grinding injures it. 
 
 Fibrous Substitutes for Hair. — -Manila fiber as a sub- 
 stitute for hair in plaster work has been the subject of 
 experiments in this country. One of the most conclu- 
 sive of these tests was made by four briquettes or plates 
 of equal size, one containing manila hemp, a second sisal 
 hemp, a third jute and a fourth goats' hair of the best 
 quality. The ends of the plates were supported and 
 weights suspended from the middle. The result showed 
 that plaster mixed with goats' hair broke at 1441/2 
 lbs. weight, the jute at 145 lbs., the sisal at 150, and the 
 manila at 195, in the latter case the hemp not breaking, 
 but cracking, and though cracked in the center, the lower 
 half of this plate, when it was suspended, held onto the 
 upper half, the manila securing it fast. The three other 
 
PLASTER, LIME, ETC. 93 
 
 plates were broken — that is, the two parts of each plate 
 had severed entirel}^. Another experiment consisted in 
 mixing two barrelfuls of mortar, each containing equal 
 portions by measure of sharp sand and lime, one of the 
 barrels, however, being mixed with a proper quantity by 
 measure of manila hemp, cut in lengths of 1^2 to 2 
 inches, and the other of best goats ' hair. On being thor- 
 oughly mixed with the usual quantity of water, the re- 
 spective compounds were put in the barrels and stored 
 away in a dry cellar, remaining unopened for nine 
 months. On examination the hair mortar crumbled and 
 broke apart, very little of the hair being visible, showing 
 that the hair had been consumed by the action of the 
 lime ; .but the other, containing the hemp, showed great 
 cohesion. It required quite an effort to pull it apart, 
 the hemp fiber permeating the mass and showing little 
 or no evidence of any injury done to it by the lime. 
 
 Sawdust as a Substitute for Hair. — Sawdust has been 
 used as a substitute for hair, also for sand in mortar for 
 wall plastering. It makes a cheap additional ^aggregate 
 for coarse stuff. Sawdust mortar stands the effects of 
 rough weather and frost when used for external plaster- 
 ing. The sawdust should be used dry and put through a 
 coarse sieve to exclude large particles. I have used it 
 with plaster for both run and cast work. It proved use- 
 ful for breaks of heavy cornices by rendering the work 
 strong and light for handling. Some kinds require soak- 
 ing or washing, otherwise they are liable to stain the 
 plaster. Several patents have been issued in America for 
 the use of sawdust in place of hair and of sand. One of 
 these is for the use of equal parts of plaster, or lime and 
 sawdust ; another is for the use of 4^/2 parts each slaked 
 lime and sawdust to 1 part of plaster, 14 P^^t of glue 
 and 1-16 part of glycerine, with a small part of hair. 
 
94 
 
 CEMENTS AND CONCRETES 
 
 Kahl's patent plaster consists of 35 per cent, of saw- 
 dust, 35 per cent, of sand, 10 per cent, of plaster, 10 per 
 cent, of glue, and 10 per cent, of whiting. 
 
 Sand. — Sand is the most widely distributed substance 
 in nature, not only in the mineral but also in the animal 
 and vegetable kingdoms. Clay contains no silica (the 
 chemical name for sand). Sand is the siliceous particles 
 of rocks containing quartz, production by the action of 
 rain, wind, wave and frost. Some kinds of sand are also 
 found inland; the deposits mark the sites of ancient 
 beaches or river beds. Sand is classed under various 
 heads, viz., calcareous, argillaceous and metallic. Sand 
 varies in color according to the metallic oxides contained 
 in them. Few substances are of more importance than 
 sand for plastic purposes. Its quality is of primary im- 
 portance for the production of good coarse stuff, set- 
 ting stuff, and for gauging with Portland or other 
 cements used for plaster work. Its function is to induce 
 the mortar or cement to shrink uniformly during the 
 process of setting, hardening or drying, irregular shrink- 
 age being the general cause of cracking. Sand is also a 
 factor in solidity and hardness; while being of itself 
 cheaper and used in a larger proportion than lime or 
 cement, it decreases the general cost of materials. There 
 are three kinds — pit, river and sea sands. They gen- 
 erally ccnitain more or less impurities, such as loam, 
 clay, earth and salts, necessitating their being well 
 washed in water, more especially for the finishing coats 
 of plaster or cement work. Pit sand is sometimes found 
 quite clean; it is generally sharp and angular. River 
 sand is fine grained, not so sharp as pit sand, but makes 
 good setting stuff. Sea sand varies in sharpness and 
 size, and for plastering it should be washed to free it 
 from saline particles which cause efflorescence. 
 
PLASTER, LIME, ETC. 
 
 95 
 
 Regarding the use of sand in mortars, it may almost 
 be spoken of as a necessary evil. Sand is necessary to 
 give body and hardness to an otherwise too soft and 
 plastic material, and the coarser and cleaner the better, 
 as the coarse particles allow the carbonic acid to pene- 
 trate further into the body of the mortar, and assist in 
 the hardening process for this reason. In the case of 
 cements of all kinds sand is only good for lessening the 
 cost of the aggregate, and in the case of the majority of 
 sands in daily use in most places the strength is reduced 
 out of all proportion to the saving effected. Brunei, in 
 the Thames Tunnel, was so convinced of this that he used 
 pure Portland cement in the arches; and General Pas- 
 ley, treating of this, recommends that only pure cement 
 should be used on all arduous works. 
 
 As to the quality of sands, they are of very wide 
 variety — so much so, that 1 part of an inferior or soft 
 clayey sand will reduce the strength of mortar as much 
 as 3 or 4 parts of clean sharp granitic sand. This is well 
 exemplified in the sand test, which is made with what is 
 called standard sand, being a pure silecious sand sifted 
 through a sieve of 400 holes to the square inch and re- 
 tained on one of 900. 
 
 Good sand for lime plaster should be hard, sharp^ 
 gritty and free from all organic matter. For coarse stuff 
 and cement for floating coats it should not be too fine. 
 Good sand for plaster work may be rubbed between the 
 hands without soiling them. The presence of salt in sand 
 and water is found not to impair the ultimate strength of 
 most mortars; nevertheless it causes an efflorescence of 
 white frothy blotches on plaster surfaces. It also ren- 
 ders the mortar liable to retain moisture. 
 
 Pine-grained sand is best for hydraulic lime; the 
 coarse-grained is best for fat limes, and coarse stuffs and 
 
96 CEMENTS AND CONCRETES 
 
 Portland cements for floating. Sand should not be nni- 
 form in size, but, like the aggregate for concrete, should 
 vary in size and form. A composition of fine and coarse 
 sand for coarse stuff, unless the sand is naturally so 
 mixed, gives the best results, for as the lime will receive 
 more sand in that way without losing its plasticity it will 
 make a harder and stronger material, whether coarse 
 stuff, setting stuff or for Portland cement work. If there 
 is plenty of fine sand and a scarcity of coarse sand, they 
 should be mixed in the proportion of 2 of coarse to 1 of 
 fine. If on the other hand, there is plenty of coarse 
 sand and a scarcity of fine, they should be mixed in the 
 proportions of 2 of fine to 1 of coarse. The proportion of 
 sand varies according to the different kinds and qualities 
 of limes and cements, also purposes. Baryte is some- 
 times used as a substitute for sand. Silver sand is used 
 for Portland cement work when a light color and a fine 
 texture is required. 
 
 Mastic. — Mastic was formerly extensively used foi 
 various purposes in which now Portland cement is chiefly 
 employed. It is still used sometimes for pointing the 
 joint between the wood frames of windows and the stone 
 work. Mastic is waterproof, heat-resisting and adheres 
 to stone, brick, metal and glass with great tenacity. Mas- 
 tic is made in various ways. Some plasterers make their 
 own. 
 
 Scotch Mastic is composed of 14 parts of white or 
 yellow sandstone, 3 parts of whiting and 1 part of lith- 
 arge. These are mixed on a hot plate to expel any mois- 
 ture and then sifted to exclude any coarse particles. It 
 is then gauged with raw and boiled linseed oil in the 
 proportion of 2 of raw to 1 of boiled oil. The sandstone 
 is pounded or ground to a fine powdered state before 
 
PLASTER, LIME, ETC. 
 
 97 
 
 bein^ mixed. The surface to be covered is first brushed 
 with Jinseed oil. 
 
 Common Mastic is prepared as follows : 100 parts of 
 ground stone, 50 parts silver sand or of fine river sand, 
 and 15 parts of litharge. These are all dried and mixed 
 and passed through a fine sieve; it then resembles fine 
 sand. This mastic may be kept for any length of time in 
 a dry place. When required for use it is gauged with 
 raw and boiled linseed oil (in equal proportions) until 
 of the consistency of fine stuff. It requires long and fre- 
 quent beating and kneading — in fact, the more it is 
 knocked up the better it works. Its fitness for use can 
 be ascertained by smoothing a portion of the gauge^with 
 a trowel. If there are any separate parts of the differ- 
 ent materials or bright spots seen the knocking-up must 
 be renewed until it is of even texture. The addition of 15 
 parts of red lead is sometimes used to increase the tenac- 
 ity of the mastic. 
 
 * Mastic Manipulation. — The walls are prepared for 
 mastic by raking out the joints and sweeping with a 
 coarse broom, and the brick work well saturated with lin- 
 seed oil. Narrow screeds about 1 inch wide are formed in 
 plaster to act as guides for floating the work plumb and 
 level. When laying the mastic it must be firmly pressed 
 on and the floating rule carefully passed over the sur- 
 face until it is straight and flush. The screeds are next 
 cut out and the spaces filled in with extra stiff mastic. 
 The whole surface is then finished with a beech or syca- 
 more hand float, leaving a close and uniform texture. 
 Mastic moldings are first roughed out with Medina or 
 other quick-setting cement. The running mold is muffled 
 so as to allow 14 i^ch for the mastic coat. 
 
 Hamelein^s Mastic. — This mastic consists of sand and 
 pulverized stone, china, pottery, shard, to which are 
 
98 CEMENTS AND CONCRETES 
 
 added different oxides of lead, as litharge, gray oxide 
 and minium, all reduced to powder, to which again is 
 added pulverized glass or flint stone, the whole being 
 intimately incorporated with linseed oil. The propor- 
 tions of the ingredients are as follows: To any given 
 weight of sand or pulverized pottery ware add two-thirds 
 of the weight of pulverized Portland, Bath or any other 
 stone of the same nature. Then to every 550 lbs. of this 
 mixture add 40 lbs. of litharge, 2 lbs. of pulverized glass 
 or flint stones, 1 lb. of minium and 2 lbs. of gray oxide 
 of lead. The whole must be thoroughly mixed together 
 and sifted through a sieve, the fineness of which will de- 
 pend on the different purposes for which the mastic is 
 intended. The method of using is as follows : To every 
 30 lbs. of the mastic add 1 quart of linseed oil and well 
 mix together either by treading or with a trowel. As it 
 soon begins to set, no more should be mixed at a time 
 than is requisite for present use. Walls or other sur- 
 faces to be plastered with this material must first be 
 brushed with linseed oil. 
 
 Mastic Cement, — Mix 60 parts of slaked lime, 35 parts 
 of fine sand and 3 parts of litharge, and knead them to 
 a stiff mass with 7 to 10 parts of old linseed oil. The 
 whole mass must be well beaten and incorporated until 
 thoroughly plastic. This mastic cement assumes a fine 
 smooth surface by troweling. It is impervious to damp 
 and is not affected by atmospheric changes. 
 
TERMS AND PROCESSES. 
 
 The following descriptions are suited to niost locali- 
 ties, though there are districts in the East and South 
 that vary somewhat from the processes as described; 
 the difference, however, is so trifling that the regular 
 plasterer will have no trouble in reconciling such differ- 
 ences. 
 
 Three-Coat WorkA — Three-coat work is usually speci- 
 fied by architects for all good buildings, but sometimes 
 two-coat work is specified for inferior rooms, closets, at- 
 tics or cellars in the same building. Three-coat work 
 makes a straight, smooth, strong and sanitary surface for 
 walls and ceilings when properly executed. The follow- 
 ing is the process for three-coat work, which consists of 
 first-coating, floating and setting. 
 
 First-Coating. — ''First-coating" is termed in the 
 United States ' ' scratch-coating. ' ' It is executed by lay- 
 ing and spreading a single coat of coarse stuff upon the 
 walls and ceilings to form a foundation for the subse- 
 quent floating and setting coats. Coarse stuff for /irst- 
 coating should be uniformly mixed or ''knocked up," as 
 commonly called. It should contain more hair than that 
 used for floating, so as to obtain a strong binding key on 
 the lath-work and form a firm foundation for the float- 
 ing coat. Coarse stuff may be tested by lifting some 
 from the heap on the point of a trowel. If it is suffi- 
 ciently haired and properly mixed the stuff should cling 
 to the trowel when held up and the hairs should not be 
 more than 1-16 inch apart. It should be stiff enough to 
 cling and hold up when laid, yet sufficiently soft and 
 
 99 
 
100 CEMENTS AND CONCRETES 
 
 plastic to go through the interstices between the laths. 
 Unless the stuff is made to the proper consistency it will 
 ''drop" — that is, small patches where the excess water 
 accumulates or at weak or too wide spaced laths will fall 
 soon after being laid. 
 
 When first-coating ceilings, the coarse stuff should be 
 laid diagonally across the laths, a trowelful partly over- 
 lapping the previous one, the one binding the other. By 
 laying the stuff diagonally the laths yield less, present a 
 firmer surface and are not so springy as when laid across 
 or at right angles to them. Laying the stuff diagonally 
 and overlapping each trowelful helps to retain the stuff 
 in its place, which otherwise is apt to ''drop.'' The stuff 
 should be laid on with a full-sized laying trowel, using 
 sufficient pressure to force it between the laths and to 
 go sufficiently through to form a rivet and lap or clinch 
 on the upper sides of the lathing. The stuff should be 
 laid fair and as uniform in thickness as possible. The 
 thickness should not exceed % inch or be less than % 
 inch. If too thick it tends to weigh down the lath work 
 and is apt to crack ; if too thin the subsequent scratching 
 is liable to cut the coat down or nearly to the laths, thus 
 leaving a series of small detached pats which are un- 
 stable and form a weak foundation for the floating coat 
 and are a source of cracks and often the cause of the 
 w^ork falling when subjected to vibration. A thickness 
 of y2 inch gives the best results. 
 
 Scratching. — Scratching is sometimes termed "scor- 
 ing," also "keying." It is done with a wooden or iron 
 scratch, which may have from one to five points. 
 Scratching is scoring the surface of the first coat to 
 obtain a key for the following coat. The first-coating 
 should be allowed to stand for an hour or two to allow 
 the stuff to get firm before proceeding with the scratch- 
 
TERMS AND PROCESSES 101 
 
 ing. If scratched while the stuff is soft it is apt to drop, 
 and unless a man is careful and light in his working the 
 scratch will go too deep and weaken the body and the 
 rivets of first-coating. A wide scratch should be slightly 
 angular at the points; if square, it should be drawn 
 across the work in a slanting position so as to give an 
 undercut key. The whole of the surface should be uni- 
 formly scratched with a moderately sharp pointed 
 scratch. The surface should be cross-scratched diag- 
 onally. Square scratching cuts and weakens the rivets, 
 especially when the scratch is drawn in the same line as 
 the laths. Good work is generally scratched with a sin- 
 gle lath. This, like other scratches, should be drawn in 
 a slanting position, so as to give an undercut score. Sin- 
 gle scratches is the best way for circular surfaces. First 
 score it diagonally across the laths and then crossways 
 diagonally, keeping the scoring rather square than loz- 
 enge-shaped. When too pointed the acute angles are 
 liable to be broken when laying the floating coat. The 
 scores should not be more than I14 inch from center to 
 center, or less than one inch from center to center. Close 
 scoring weakens the body of the first-coating, while wide 
 scoring affords insufficient key. Scratching with a single 
 lath requires thrice or even more time than if done with 
 a four or five pointed scratch, but the work is stronger, 
 as the body and the rivets of the first coating are; not 
 cut too deep or otherwise weakened. In some instancies — 
 such as a thin body of first-coating already mentioned — • 
 the scoring is so deep that the body of the work is cut 
 into a series of detached parts. By using a single lath 
 or point the scoring is also more uniform and better un- 
 dercut, thus obtaining a stronger surface and a better 
 key for the floating; coal^.^ The e^cMjtionjal time required 
 for '^single scx'atGhing\\shouJri be caken mto x}oi:j^^^ 
 
102 CEMENTS AND CONCRETES 
 
 tion, and annotated and allowed for when making speci- 
 fications and estimating. All scratching should be done 
 uniformly, taking care not to miss any parts, especially 
 round door and window frames, wood grounds or where 
 there may be jarring or vibration. On the regular and 
 proper scratching depends the key and stability of the 
 succeeding coats. Scratching with the point of a trowel 
 should not be permitted. The use of a trowel as a 
 scratch is detrimental to the strength of the stuff and the 
 key. The sharp edge of the trowel cuts the hair and 
 thus weakens the stuff. The smooth and thin plate of the 
 trowel leaves a smooth and narrow key; the smooth side 
 of the key presents no attachment for the second coat, 
 while the deep part of the key is too narrow to receive 
 its due portion of stuff to fill it up, thus leaving a space 
 for contained air and a more or less hollow and unsound 
 body. 
 
 Rendering, — The first coat on brick, stone or concrete 
 walls is called rendering. Before laying the coarse stuff 
 the superfluous mortar in the joints of brick or stone 
 walls should be cleared off*, as the mortar used by brick- 
 layers and stonebuilders often contains live or imper- 
 fectly slaked lime, which in many instances is the cause 
 of the plaster work blowing or scaling off. The walls, 
 whether of brick, stone or concrete, should be well swept 
 with a hard coarse broom and thoroughly wetted to cor- 
 rect the suction, which otherwise would absorb the requi- 
 site moisture from the coarse stuff, causing it to become 
 inert and dry, consequently weak and non-adhesive. In 
 some cases the joints of brick-work should be raked out 
 and the face of stone walls roughened by picking. The 
 coarse stuff for rendering walls does not require so much 
 hair or to be used so stiff as fci^ coating lathwork. First- 
 coating ^r reader ing ]s ge^neraHy looked u^^on as a simple 
 
TERMS AND PROCESSES 
 
 103 
 
 process, but it should be carefully laid and scratched, as 
 it is the foundation for the other work. 
 
 Floating, — Floating or second-coating, termed brown- 
 ing," is the laying of the second coat of., coarse stuff on 
 the first coat when dry to form a straight surface for the 
 finishing coat. If the first coat has been standing for 
 some time it should be well swept to clear off any dust 
 that may have accumulated during the interval between 
 the application of the coats. Where the coarse stuff is of 
 a porous nature a damp brush should be passed lightly 
 over the first coat as the work proceeds to prevent the 
 moisture being sucked out of the second layer, which, if 
 too dry, would tend to crack and fall away. The coarse 
 stuff for floating should be used in a softer state than 
 for first-coating, because when too stiff the extra press- 
 ure required for laying is apt to crack the first coat on 
 lath work. It also goes more freely and firmly into the 
 recesses of the scratching. (It may be here mentioned 
 that a mortar called ^^dogga'' is extensively used in 
 South Africa for plaster and building work. Dogga is 
 the ground dug up and tempered with sand, about 2 to 
 1 for rendering and floating. Heavy ground requires 
 more sand. Lime is very expensive in that country and 
 is only used for the best class of work.) Floating for 
 lime plastering consists of four parts: (1) Plumbing 
 and levelling ' ' screeds ' ' to act as bearing for the floating 
 rule and running mold; (2) flanking or filling in the 
 spaces between the screeds; (3) scouring; (4) keying the 
 surface. These parts are performed as follows: 
 
 Screeds.^ — In good work the wall screeds are plumbed 
 and the ceiling screeds levelled. Wall screeds are 
 plumbed by forming ''dots" at the top and bottom of 
 the internal and external wall angles. If there are wood 
 grounds to receive wood skirtings they are used instead 
 
CEMENTS AND CONCRETES 
 
 of bottom dots. The dots are made by 
 driving two nails through the first coat 
 into the studs or joints of the wall, 
 allowing them to project about I/2 inch 
 §Q beyond the face of the first coat. The 
 position of the top nail should be imme- 
 I diately beneath the cornice bracket. If 
 I there is no bracket the depth of the 
 I cornice should be allowed for. The 
 ^ bottom nail is placed in a liije with the 
 ^ upper member of the skirting molding, 
 g The nails should be pla(?ed perpendicu- 
 g lar with each other, otherw^ise the 
 plumb-bobline will not work in unison 
 with the gauges. The dots are plumbed 
 by means of a plumb-rule. If the walls 
 are too high for an ordinary sized 
 plumb-rule to be used a chalkline, with 
 a plumb-bob attached, and two wooden 
 gauges will be required. Illustration 
 No. 3 shows the nails, gauges and 
 plumb-bobline in position. BB are the 
 nails in the wall, one just below the 
 cornice bracket and the other a little 
 above the floor line; AA are the gauges 
 with the line hanging fair with their 
 shoulders, being the correct position 
 >B when the nails are plumb. The gauges 
 are generally cut out of a strong lath. 
 They must be made exactly to the same 
 length. The plasterer at the top holds 
 the end of one gauge on the top nail, 
 with the chalk-line resting on the shoul- 
 der of the gauge, while the plasterer 
 
TERMS AND PROCESSES 
 
 105 
 
 at the bottom holds the other gauge on the bot- 
 tom nail with one hand and guides the plumb-bob 
 with the other. The nails are now driven in as re- 
 quired until they are plumb. Care must be taken to 
 allow for a fair thickness for the floating coat. This 
 should not be more than % inch or less than % inch. 
 When working from a wood ground the top dots should 
 be kept a little inside the plumb-line to allow for the 
 traversing of the cornice screed, because this screed and 
 the gathering at the bottom of the cornice are apt to 
 throw the wall out of plumb unless cut off or allowed for. 
 The dots are completed by laying narrow strips of 
 gauged coarse stuff up to and in a vertical line with the 
 top and bottom nails- the floating rule is then applied 
 and the stuff worked down until flush with the nails. The 
 dots should not be wider than the width of the floating 
 rule, as the rule when bearing on the nails can only be 
 worked with an up-and-down motion, taking in only its 
 own width. The length of the dots may vary from 5 
 to 7 inches, according to the bearings required for the 
 cornice and skirting running mold. Narrow screeds are 
 easier, quicker and truer made than wide screeds. The 
 latter are apt to have a more or less wavy surface. This 
 applies more especially to ^^laid screeds'' — that is 
 screeds that are simply laid and ruled off without dots 
 or other bearings. 
 
 Lath dots are sometimes used instead of nail dots ; they 
 are generally used on ceilings and lathed partitions ; they 
 are not so liable to crack the first coat as nails. They 
 are formed by laying a strip of coarse stuff and placing 
 thereon a straight lath about 6 inches long and then 
 applying a plumb-rule or plumb-bobline as described 
 for the nail dots. The lath gives strength and resist- 
 ance while working the floating rule. After the screeds 
 
106 
 
 CEMENTS AND CONCRETES 
 
 are finished the laths are taken out and the spaces made 
 good. Having finished all the top and bottom dots, the 
 top and bottom longitudinal spaces in a line with the 
 dots, or, in other words, the screeds are laid with coarse 
 stuff. The long floating rule is then applied, bearing on 
 the dots and working up and down in a slanting posi- 
 tion, a plasterer working the rule at each end, and work- 
 ing together so as to keep the rule square on edge and 
 uniformly level. Any surplus stuff is taken off the rule 
 and applied to make up any hollow parts in the screed 
 or returned to the gauge board, as the case may be. If 
 the screeds are extra long another man (sometimes more) 
 is required to work at the center of the rule, also clean 
 the surplus stuff off, and make up any deficiencies in the 
 screed. After the screeds are finished, the nails must be 
 extracted to avoid rust discoloring the finishing .coat. 
 Large surfaces on walls or ceilings should be divided in- 
 to bays by narrow screeds placed from 6 to 9 feet apart. 
 This affords more freedom and regularity for laying and 
 ruling off. Gauged coarse stuff is sometimes used for 
 the main screed, i. e., the wall and ceiling screeds on 
 which the cornice is run. In this case the screeds are 
 finished smooth, or so that they only require a very thin 
 or filling-up coat of gauged putty for the cornice screeds. 
 The splayed edges of screeds, especially gauged screeds, 
 should be cut square. A splayed edge being generally 
 smooth, affords little or no key, and also being unequal 
 in thickness, makes a bad joint for the floating coat. 
 If there are any breaks in the room, the screeds must be 
 set off square from the side walls, and the projections 
 at each angle of the breast made equal. The sides are 
 best squared with a large wooden square, and the pro- 
 jections regulated with a gauge. 
 
 Flanking. — Flanking or filling in consists of laying 
 
TERMS AND PROCESSES 
 
 107 
 
 the intervening spaces between the screeds with coarse 
 stuff, and then ruling the surface straight and flush with 
 the screeds, with a floating rule. Two squads of men, two 
 or three in each squad, are required for this purpose — 
 one squad on the floor, and the other on the scaffold. If 
 the height of the room necessitates more than one scaf- 
 fold, an additional squad is required for each interven- 
 ing scaffold. In the latter case, the distance between the 
 top and bottom screeds would be too great to allow a 
 floating rule to be conveniently worked. To overcome this 
 difficulty, intermediate screeds must be made at conven- 
 ient distances. This is done by stretching a chalk-line 
 from the top to the bottom screed, and then forming dots 
 flush with the line, and laying the screeds as previously 
 described. The coarse stuff for flanking should be laid 
 upwards, and in an angular line. This plan is not so apt 
 to spring the lath or crack the key at the deepest, which 
 is the thinnest part of the first coat, as if laid across the 
 laths. After a bay is laid, the surface is straightened 
 w4th a floating rule. A plasterer at the top and one at 
 the bottom works the rule together uniformly up and 
 down with a cutting motion, and keeping it in a slightly 
 angular position, so that any surplus stuff may not fall 
 on the man below. A rule should not be worked on 
 either of its face edges, as by so doing the face becomes 
 round and uneven, and conducive of unequal screeds. 
 The filling in and ruling off is continued until all the 
 walls are completed. When elaborate ceilings have to be 
 done, involving the expenditure of much time, the top 
 longitudinal screeds are only formed, and the floating of 
 the walls left until three or four days before the setting 
 can be begun, as the setting coat made from some limes 
 adheres better when the floating coat is partly green, or 
 at least not bone dry. As previously mentioned, the 
 
108 CEMENTS AND CONCRETES 
 
 whole process of preparing lime plaster and laying it on 
 the walls in thin coats, with a considerable space of time 
 between the coatings, is conducive to the ultimate hard- 
 ness of the whole, the lime being first slaked and then 
 scoured, all this time being exposed to the carbonic acid 
 of the atmosphere. Again, each coat is long exposed to 
 the same influence before being covered with the next, 
 thus enabling each coat to harden by a natural process 
 before the following coat is laid. All things being equal, 
 it is advisable to allow each coat to stand as long as pos- 
 sible before proceeding with the next. Where the wall 
 surface is irregular, causing extra thick parts in the 
 floating coat, the hollow parts should be rendered or 
 
 dubbed out," and the surface scratched before laying 
 the floating coat. The dots for the ceiling screeds are 
 formed close to the cornice bracket. If there are no 
 brackets, the projection of the cornice must be allowed 
 for. Lath dots are best for ceiling screeds. They are 
 formed at all the angles, and made level all round the 
 ceiling. This is done with the aid of a parallel ceiling 
 rule." When all the dots are made, the screeds are fin- 
 ished, and the surface flanked in as already described. 
 
 For common work, the wall screeds are seldom 
 plumbed; but if there are breaks in the room, the ex- 
 ternal angles, which are more noticeable, should always 
 be plumbed. For this class of work two men generally 
 work together. Working from the floor upwards, one 
 man lays a coat of coarse stuff about 7 inches wide, and 
 as high as he can conveniently reach up on both sides of 
 the internal angles ; his colleague follows on with a float- 
 ing rule and rules them straight. Before finishing the 
 screed, the rule is applied on the portion done, and grad- 
 ually moved up until one end reaches the cornice line, 
 to see if there Ik a sufficient thickness for the upper part 
 
TERMS AND PROCESSES 
 
 109 
 
 of the screed. The space between the first-coating and 
 the face of the rule shows the thickness available for the 
 floating coat. The desired thickness is obtained by lay- 
 ing more stuff on the screed, or working it down, as 
 the case may be. As the floating rule cannot be worked 
 close up to the angle, a seam of coarse stuff is formed in 
 the angle. 
 
 To allow for shrinkage, and to obtain a flrm and 
 square angle, the seams are left until all the floating is 
 done, after which they are cut oft' square and flush with 
 the floating. This is done with a laying trowel, working 
 it on its flat on the firm floating. Any defects in the 
 angles are made good when scouring the float- 
 ing. After the vertical angle screeds are firm, 
 horizontal screeds are laid at the highest conven- 
 ient line, and ruled with a floating rule bearing 
 on the vertical screeds. The intervening spaces are then 
 flanked* in by laying with coarse stuff until flush with 
 the screeds. The surface is sometimes ruled fair with a 
 floating rule, but more often straightened with a darby. 
 After the scaffold is erected, the top portions of the ver- 
 tical screeds are laid and ruled with a floating rule, 
 working it so as to bear on the lower part of the screed 
 previously made, which gives a bearing and guide for 
 the rule. After allowing for the depth of the cornice 
 (if not bracketed), the top horizontal screed is then 
 laid and ruled with a floating rule bearing on the ver- 
 tical screeds. The intervening spaces are then filled in 
 with coarse stuff, and ruled in or darbied as previously 
 described. The ceiling screeds are made close to the cor- 
 nice bracket, or (if not bracketed) in a line with the 
 outer member of the intended cornice. A screed is first 
 made at each of the long sides of the ceiling, and when 
 firm the end screeds are laid and ruled, using the long 
 
ilO CEMENTS AND CONCRETES 
 
 screeds as bearings for the floating rule. If the scaffold 
 is in position before the floating is commenced, the 
 vertical screeds should be formed in one operation. A 
 plasterer on the floor lays the lower part of the screed, 
 while his partner on the scaffold lays the upper part, 
 after which both work with floating rule together in 
 their respective positions. Where practical all screeds 
 should be finished in one operation. In the event of a 
 screed being too long for an ordinary sized rule to take 
 in the whole length and work it in one operation, the 
 screed can be made straight by working the rule back- 
 wards and forwards from end to end, testing the 
 straightness by applying the rule on various parts of the 
 screed. The straightness is further proved by lightly 
 stretching a chalk-line from one end to the other end 
 of the screed. After the screeds are firm, the main 
 portion of the ceiling is laid with coarse stuff flush with 
 the screeds, and then made fair with a darby. 
 
 When floating large surfaces with a darby, it should 
 be worked in all directions — longwise, crosswise, * and 
 diagonally and finishing with a circular motion. For or- 
 dinary work a darby is an excellent tool for straighten- 
 ing large surfaces of floating and setting. It also forms 
 a pleasing and easy surface on circular work. For base- 
 ment and attic rooms a darby properly manipulated will 
 form fairly straight screeds as well as the main surfaces. 
 When floating large ceiling or wall surfaces for plain 
 work, or where it is not necessary that they should be 
 perfectly straight,, involving time and material, a hol- 
 low surface is preferable to a round surface. A hol- 
 low surface is not so noticeable, and is less objectionable 
 to the eye than a round surface. It will be understood 
 that a hollow surface, to be pleasing to the eye if noticed, 
 should flow gradually and regular from the screeds to 
 
TERMS AND PROCESSES 111 
 
 the center of the surface, and not suddenly or in wavy 
 parts or patches. 
 
 There is an inferior kind of floating practiced by 
 piece-workers, in some districts, for cottage work, and 
 even some of the modern jerry-built houses. This is 
 executed by floating direct from the walls in one coat. 
 The surface is sometimes dry-scoured with a ''nail hand 
 float, ' ' water and proper scouring being unknown in this 
 class of so-called plastering. The ceilings are simply 
 laid with coarse stufi:', and the ridges and smooth sur- 
 face left by the trowel are worked down and roughened 
 by a few rubs with a hand float. This porous and cracked 
 shell is finished with setting stuff, gauged with just as 
 much plaster as will hold the materials together for the 
 time being. The minimum of (or possibly less) trowel- 
 ling is attempted; a stock brush being found a more 
 easy and speedy tool than a trowel for finishing. The 
 brush is made to perform the trowelling and brushing 
 off in one operation. This shoddy work is unsafe and 
 unsanitary, and ought not to be tolerated. 
 
 Scouring Coarse Stuff. — Scouring floated coarse stuff 
 is of great importance. It not only consolidates and 
 hardens the surface, but also prevents cracks in its own 
 body and the subsequent setting coat. For these reasons 
 it should be well and sufficiently done. The straightened 
 coarse stuff should be allowed to stand to permit of 
 shrinkage, evaporation of surface moisture, and a firm 
 surface before proceeding with the scouring. Working 
 a hand float on a soft surface tends to form "water 
 blubs'' and hollow parts. When the surface is firm, 
 but not dry, the work is fit to scour. This is done by 
 the plasterer having a hand float in one hand, and a 
 stock brush in the other, with which he sprinkles water 
 on the surface, and vigorously applies the float with a' 
 
112 CEMENTS AND CONCRETES 
 
 rapid circular motion, using a little soft stuff to fill up 
 any small holes or inequalities that may have been left 
 after the floating rule. Care must be taken that no part 
 is missed or less scoured and that the whole surface is 
 thoroughly and uniformly scoured. The floating should 
 be scoured twice, or for best work three times, and allow- 
 ing the work to stand from three to five hours, accord- 
 ing to the state of the atmosphere, between the first and 
 second scouring, and one day between the second and 
 third scouring. The final scouring should be continued 
 until there is little or no moisture left on the surface. 
 To obtain the same strength and solidity, all other things 
 being equal, coarse stuff composed with a weak lime or 
 containing inferior or an excess of sand, or having in- 
 sufficient hair, or sparsely tempered and used in an 
 over-soft condition, requires a greater amount of scour- 
 ing than coarse stuff which is composed with a strong 
 lime, or containing good sand and in due proportion, or 
 with an ample quantity of hair, or well tempered, and 
 used in a moderately stiff yet plastic condition. Even 
 with extra scouring the ultimate strength of inferior 
 coarse stuff is remote and doubtful. This simple mat- 
 ter is a witness to the fact that inferior or insufficient 
 materials require more labor than good and sufficient 
 materials and that the results are somewhat vague and 
 often unsatisfactory. 
 
 Keying, — All plastic materials have great adhesive 
 powers, especially to each other. Yet when laying a thin 
 body of fine material on a coarse material which has a 
 more or less smooth, dry and absorptive surface, such as 
 laying setting stuff on floated coarse stuff, the adhesion 
 is partly nullified. Portland cement or hydraulic limes, 
 w^hich set nearly as soon as laid, require no scouring, and 
 being left from the floating rule with an open grained or 
 
TERMS AND PROC'eSSES 
 
 113 
 
 rough surface, a natural key is obtained for the final 
 coat; but coarse stuff, which only sets or becomes hard 
 by evaporation of its moisture, must be scoured to con- 
 solidate the yielding and soft body. Scouring leaves a 
 close-grained and somewhat smooth surface, offering lit- 
 tle or no key to the setting coat. The floated coat being 
 often dry before the setting coat is applied, the suction 
 varies greatly; sometimes it is regular, at other times it 
 occurs in patches. Sometimes the suction is so excess- 
 ive that the setting stuff dries up and peels as soon as 
 laid, and in other instances the reverse occurs, there 
 being no suction at all. In the latter case the setting 
 stuff runs downwards in the form of globules or in rivu- 
 lets. These defects may to a certain extent be corrected 
 by laying the setting stuff while the floating is still 
 green, or by saturating the surface if the floating is dry. 
 Yet to obtain permanent cohesion in the two coats it is 
 necessary to key or roughen the surface. This is best 
 done by brushing the surface as soon as scoured with a 
 stiff whalebone broom or with a wire brush. A common 
 plan is to dry scour with a ^^nail float'' — i.,.e., a hand 
 float with the point of a nail projecting about Yg inch 
 beyond the sole of the float. When this method is em- 
 ployed the float should be worked in a close circular 
 motion so as to leave a series of close and irregular in- 
 dents. The usual and careless way of working the float 
 in a wide circular motion leaves the indents too wide 
 apart to give a sound and uniform key: indeed, this 
 method is of little service. A new tool for keying coarse 
 stuff has been recently introduced, which is called a 
 ''devir' and is similar to the nail float, with the excep- 
 tion that there are four nail points projecting on the 
 sole, one of which is placed about 1^2 inches from each 
 angle. The process of keying the coarse stuff with this 
 
114 CEMENTS AND CONCRETES 
 
 is termed "devilling/' The work is more speedily and 
 better done with the ''devil" than with the nail float. 
 
 After the floating is flnished the next part of interior 
 plaster work is the running of the cornice, and then fin- 
 ishing the ceiling and walls; but in order to continue 
 the methods of setting, the running of the cornice, etc., 
 are described in subsequent pages, and the setting and 
 other parts of wall work are first described as follows : 
 
 Setting, — Setting is the laying and finishing the final 
 coat on fioating, termed ''finishing," and "hard finish" 
 or "putty coat." In the best w^ork great skill and care 
 is required to make the surfaces perfectly true and uni~ 
 form in color, smoothness and hardness. The material 
 for three-coat work is generally known as "setting 
 stuff." The mode of making has already been de- 
 Scribed. Setting stuff should not be applied until the 
 floating is quite firm and nearly dry, to allow for any 
 contraction that may take place in the floating. If the 
 floating should become quite dry during the time re- 
 quired for cornice and ceiling work, or where subjected 
 to strong winds or a warm atmosphere, it should be well 
 wetted a day or two before the setting coat is com- 
 menced. This prevents the too rapid absorption of mois* 
 ture from the setting coat and gives a closer union of 
 the floating and setting coats. Before wetting copi- 
 ously, a small portion of the floating should be tested 
 with a wet brush to ascertain the degree of suction. In 
 some floating there is no suction, or at least there is 
 none until the surface has been dampened and the glaze 
 and sometimes grease has been washed off. Glaze is 
 caused by slightly hydraulic lime, also by insufficient 
 scouring. Glaze is more noticeable on first-coating 
 which has been left smooth by the laying trowel. Grease 
 occurs through friction, also dirt where the float is left 
 
TERMS AND PROCESSES 115 
 
 long exposed. These matters of excessive and non- 
 suction, dry, glazed or greasy surface, either singly or 
 in combination, also smooth or unkeyed floating, are the 
 cause of cracked or scaly setting, which one sees more or 
 less in a plaster career. It is therefore absolutely neces- 
 sary, to insure perfect cohesion of the two coats, that 
 the floated surface should be uniformly keyed, clean and 
 damp before the setting coat is layed. Setting consists 
 of laying the stuff, scouring, trowelling and brushing the 
 surface. 
 
 Laying Setting Stuffs — The setting stuff is laid in two 
 coats, the second following immediately upon the first. 
 The laying is best done with a skimming float, which 
 leaves the face of the first coat rougher to receive the 
 second than if done by a laying trowel, which leaves it 
 smooth. The second coat should also be laid with a 
 skimming float, which leaves a more open grain for the 
 purpose of scouring. When laying setting stuff some 
 men take a trowelful or skimming-floatful off the hawk 
 and stoop to spread the stuff from bottom to top with 
 an upward motion, laying the joint with a return down- 
 ward motion; but a smart man can take a trowelful or 
 floatful of stuff and spread it with a downward motion 
 from top to bottom and lay the joint with the return mo- 
 tion, this saving one stoop in each spread or floatful. 
 This is similar to laying setting stuff on a ceiling. A 
 man who has a thorough command of the trowel hand 
 always lays the stuff in a long even spread outward, 
 and lays the joint with the inward return motion. After 
 one side of a bay or wall is laid the surface is then 
 scoured, trowelled and brushed. 
 
 Scouring Setting Stuff. — The importance of good and 
 sufficient scouring of setting stuff with water cannot be 
 too strongly insisted upon. The scouring and the water 
 
116 CEMENTS AND CONCRETES 
 
 combined consolidate, harden and render the surface of 
 a uniform texture and evenness. The work must be well 
 and thoroughly scoured, twice with water and an ordi- 
 nary hand float and finally with a cross-grained float. 
 The hand float is worked with a short and rapid circular 
 motion and sprinkling water uniformly with a stock 
 brush until the surface is uniform in moisture and tex- 
 ture. After a rest to allow the stuff to shrink the scouring 
 is repeated, and then it is ready for the final scouring. 
 This is best done with a cross-grained hand float, which, 
 having sharp square edges, cuts off all ridges and leaves 
 the setting with a uniform and even surface that cannot 
 be so quickly or as well done with an ordinary hand float. 
 Water is more sparingly used for the final scouring, 
 using only as much as will moisten the surface and allow 
 the float to work freely. The scouring is continued until 
 a dense, even and close-grained surface is obtained for 
 the trowelling. 
 
 Trowelling and Bintshing Setting Stuff. — Trowelling 
 setting stuff is best done by the use of a half worn 
 trowel (commonly called a polisher''), the edges of 
 which should be perfectly straight and parallel. Some 
 men use an old and worn trowel with the point narrower 
 than the heel. This shaped trowel should never be used 
 for high class work, since, not being parallel, the press- 
 ure when trowelling is not equal, and the heel or widest 
 part is apt to score the surface of the setting. The 
 trowel and water should be perfectly clean to prevent 
 any discoloration. The trowelling should loe done by 
 one man following up the other, who is finishing the final 
 scouring. This is done by the plasterer having a polish- 
 ing trowel in one hand and a stock brush in the other, 
 with which he sprinkles water on the surface and works 
 the trowel in long and vigorous strokes, first downwards 
 
TERMS AND PROCESSES 117 
 
 and upwards, and then crossways or diagonally. This is 
 repeated, using the water more sparingly and finishing 
 or ''trowelling off with an up-and-down motion and 
 leaving the surface free from "fat" or ''glut.'^ The 
 work is then brushed with a wet stock brush, first up and 
 down, then crossways, afterwards up and down a sec- 
 ond time. The brush is then semi-dried by violent shak- 
 ing, or rubbing on a clean board, the work again being 
 brushed as before and finished perpendicular. 
 
 General Remarks on Setting. — When the work is re- 
 quired for painting the setting stuff is laid on the form 
 of screeds, and when firm the intervening spaces are 
 laid flush with the screeds atid the whole surface ruled 
 fair with a floating rule. Should there be any hollow 
 or soft places (the latter being liable to shrink), they are 
 filled in with more setting stuff and ruled over again. 
 This is repeated until the whole surface is true and uni- 
 form in thickness and firmness. The whole surface can 
 be scoured, trowelled and brushed in one operation. 
 This method has the advantage of saving joints at the 
 connections between the height a man can lay and finish 
 the setting stuff. 
 
 Joints, unless carefully done, are an eyesore, as they 
 are liable to be more or less discolored and uneven on 
 the surface. The best method for making joints and 
 setting stuff, where it is inconvenient to lay and finish 
 the whole surface in one operation, is to leave the edge 
 of the joint untrowelled, leaving a scoured margin so 
 that the adjoining portion can be laid and scoured with- 
 out spoiling the trowelling of the first portion. For in- 
 stance, when setting the walls of a room one scaffold 
 high the top parts are laid down to the level of the 
 scaffold, or as far as convenient, and the surface scoured 
 and trowelled. The latter must not extend to the end 
 
118 CEMENTS AND CONCRETES 
 
 of the scoured part, so as to leave an untrowelled margin 
 about 4 or 5 inches wide until the scaffold is struck. 
 After the scaffold is removed the lower portions of the 
 walls are laid flush with the untrowelled margin, and 
 then the surface is scoured as before, always going well 
 over the joint. The surface is then finally scoured with 
 a cross-grained float, taking care to moisten and rescour 
 the untrowelled margin to render the whole of the 
 scoured surface equal in texture and moisture for trowel- 
 ling. The surface is then trowelled and brushed as al- 
 ready described, taking care to go over the trowelled and 
 brushed joint. By this method no joints are visible, and 
 an even surface is obtained. When the suction is slow 
 or irregular, causing the setting stuff to run or be soft 
 in places, float the surface with a darby until sufficiently 
 fair and firm to be scoured. A darb}' is very useful for 
 forming a fair surface on setting stuff before scouring 
 and trowelling. It forms the next best surface to a 
 ruled surface. A darbied surface is better and truer 
 than a laid surface. 
 
 No more setting stuff should be laid than can be con- 
 veniently finished in one operation or day. Where prac- 
 tical, one side of a wall should be finished in one piece, 
 and sufficient men should be employed thereon. If the 
 room is not too high, one man or set of men may do the 
 upper part, while another man or set of men does the 
 lower part. The joints are then made while the setting 
 stuff is green. In high rooms, several sets of men work 
 together on different scaffolds, each about 6 ft. 2 in. 
 apart. All angles should be ruled in with a long float- 
 ing rule. External angles are sometimes formed by 
 nailing a running rule or a straight edged plumb on one 
 side of the wall, to act as a guide, but external angles are 
 generally finished with a run cement bead or an arris. 
 
TERMS AND PROCESSES Il9 
 
 An average thickness of % inch of setting coat when 
 finished gives the best result. It should not exceed 3-16 
 inch, or be less than 1-16 inch in thickness. If too thick, 
 it is liable to crack and flake; if too thin, it is liable to 
 peel. Where extra strength, and cohesion between the 
 floating and setting coats is desirable, the first coat of the 
 setting has a little white hair mixed with it. White hair 
 does not show through the last coat. 
 
 Common Setting. — Common setting for wall and ceil- 
 ings is generally used for second-class work. It is done 
 by laying one coat of setting stuff with a skimming float, 
 and scouring and trowelling once and brushing twice. 
 Where the floating cracks by contraction, or by using in- 
 sufficient hair in the coarse stuff, or by w^ant of scouring, 
 or where the work is green, the cracks are knocked in 
 with a hammer. The indents are then filled up with 
 gauged setting stuff, and the whole surface laid with a 
 coat of this material, on which a coat of neat setting stuff 
 is laid, scoured, trowelled, and brushed in the usual 
 way. 
 
 Skimming. — Skimming is an inferior class of setting, 
 and is only used for the most common work. It is done 
 by laying a coat of fast-setting stuff with a laying trowel. 
 The stuff is skimmed over the floating as thin as possible, 
 using only as much stuff as will whiten and smooth the 
 floating surface. It is trowelled once, and brushed as 
 soon as laid. 
 
 Colored Setting. — A beautiful color and brilliant finish 
 for walls is obtained by mixing an equal quantity of 
 sifted marble dust with setting stuff and using this 
 
 marble setting stuff" as a final coat. Ordinary setting 
 stuff is greatly improved by substituting a part of mar- 
 ble, or alabaster, or gypsum dust, equal in bulk to half 
 the sand generally used. The marble dust should be as 
 
120 CEMENTS AND CONCRETES 
 
 coarse as the sand. Crushed spar is sometimes used in 
 setting stuff to obtain a sparkling surface. Barytes, sco- 
 ria, and slag are sometimes used as a substitute for sand, 
 for coloring and hardening purposes. Brick dust is also 
 used for coloring, and weather and heat resisting pur- 
 poses. Ground glass as used by Indian plasterers gives 
 a sparkling surface. Setting stuff may also be colored 
 with the same materials as described for colored stucco. 
 Where marble dust or any of the above materials are 
 used, they should not be added until the setting stuff is 
 required for immediate use. They should not be used 
 until perfect amalgamation has ensued. 
 
 Gauged Setting. — Gauged setting is used where the 
 floating is soft, or where the work is required for imme-' 
 diate use, and also for finishing gauged floating. This 
 is performed by one man laying the gauged stuff with 
 a skimming float, while his partner follows up with a 
 darby to lay the surface fair. Another batch of setting 
 stuff is then gauged, and one man lays a thin coat with 
 a trowel, and the other man follows immediately and 
 .trowels the work before it is set. The surface is finished 
 by brushing with a semi-wet brush. Gauged setting 
 should never be scoured unless the size water is used in 
 the gauge to delay the setting, as it will kill the plaster 
 and render the stuff useless. Even if size water is used, 
 the scouring must be slightly and quickly done. If a 
 gauged surface is desirable, a fair and hard surface is 
 obtained by simply darbying and trowelling as soon as 
 laid. 
 
 Gauged Putty 8et.\ — Ceilings are sometimes set with 
 gauged putty. This is best done by first laying a 
 ''scratch coat'^ of gauged putty with a skimming float, 
 and then passing a hand float over the surface (before 
 the stuff is set) to lay down any ridges, and make the 
 
TERMS AND PROCESSES 
 
 121 
 
 surface more even to receive the second coat. This is 
 laid with a laying trowel, and then trowelled before the 
 stuff is set. The surface is then finished with a semi-wet 
 brush. Trowelling after the stuff is set, or even has 
 begun to set, kills the stuff, and causes it to peel. A 
 little washed sand added to the putty makes a stronger 
 surface, and not so apt to peel. 
 
 Putty Set. — In some districts common ceilings are fin- 
 ished with a thin coat of neat lime putty ; but unless the 
 putty is made from grey limestone, or is of a hydraulic 
 nature, the work is more or less we^k, and in most cases 
 practically useless. 
 
 hiternal Angles. — The setting coat of internal angles 
 on room walls should be ruled fair and then cleaned out 
 with a feather-edged rule. Before scouring the setting 
 stuff, the angles should be squared and made straight 
 with an angle float. The angle float is a tool now unfor- 
 tunately seldom used, but it is the best tool for making 
 a true angle. In the absence of an angle float, the angle 
 should be made fair and square, with a cross-grained 
 float, and finished with a margin trowel or the heel of a 
 laying trowel. The common way, used in some districts, 
 of finishing an angle with a gauging or pointed trowel, 
 should not be encouraged, as it is impossible to make a 
 true angle with a tool of this shape. 
 
 External Angles. — The external angles of room walls 
 and windows are generally finished with a bead, but in 
 some instances with a plain arris, splay, or small mould- 
 ing. They are formed with Parian or other white 
 cement, and usually run after the floating is done. The 
 floating should be cut square on each side, and down to 
 the brick or lath work. After dusting and wetting the 
 foundation, a running rule is fixed on one side, and then 
 the bead or arris is run. The run edges form bearings 
 
J 22 CEMENTS AND CONCRETES 
 
 lor the setting coat. A run arris is more speedily done 
 and truer than a ruled and trowelled arris. In some 
 districts wooden beads are used for external angles. The 
 floating is cut down at each side of the bead, to allow the 
 quirks to be formed when the setting coat is laid. When 
 the setting coat is trowelled, the quirks are formed by 
 applying a large-headed nail on the bead, and drawing 
 it up and down to cut the stuff out. They are then fin- 
 ished by working a laying trowel up and down until 
 smooth and true, and afterwards wet-brushed. The 
 bead quirks are sometimes cut out by aid of a wooden 
 template, also by laying a straight edge on the work as 
 a guide for cutting the stuff out. They are then finished 
 with a trowel and brush, as already described. 
 
 Skirtings, — Skirtings or base, are sometimes formed 
 in wood, but are often formed in cement. Cement skirt- 
 ings are far more sanitary than wood skirtings, as the 
 former connects the wall and the floor in one solid fire- 
 resisting and vermin-proof body, whereas wood skirtings, 
 owing to their nature and construction, afford a ready 
 harbor for vermin, and offer but little or no resistance 
 to damp and fire — indeed, their hollow formation pre- 
 sents a vent in the case of fire. Parian or other white 
 cement is generally used where a fine finish is desirable, 
 and Portland cement where the work is exposed to wet 
 and hard wear. Skirtings are generally run by first 
 roughing out the plinth by aid of a gauge rule bearing 
 on the floating, and then forming a running screed, and 
 fixing a running rule on the plinth. The skirting mould- 
 ing is then run in the usual way, after which the running 
 rules are taken off, and the plinth set. The mould plate 
 should be cut to form about 1 inch of the top part of the 
 plinth, to form the arris, and a bearing when setting the 
 plinth. The annexed illustration (No. 4) shows the 
 
TERMS AND PROCESSES 
 
 123 
 
 method of forming the core and plinth, and running 
 the moulding. Fig. 1 shows the gauge rule (G) in posi- 
 tion to form the core (C). The gauge rule is from 3 
 feet to 4 feet in length. The plinth is formed by first 
 roughing out with gauged stuff, and then drawing the 
 gauge rule along the floating to form the core, and a 
 fair surface for the running screed. Fig. 2 shows a sec- 
 tion to form the core (C). The gauge rule is from 3 
 (R) fixed on the plinth or core (C). 
 
 TwO'Coat Work. — This is a cheap method of plaster- 
 ing, and only used for common work, such as the walls 
 of factories, warehouses, &c. It is performed by laying 
 one coat of coarse stuff and then forming the surface 
 fair with a darby, after which it is scoured once. It is 
 then finished by laying a thin coat of setting stuff over 
 the surface, and then trowelling once and brushing twice 
 wet and once semi-wet. 
 
 One-and-a-Half-Coat Work, — This is sometimes termed 
 ' ' coat-and-half work." It is a species of two-coat work 
 —in fact^ it is so termed in some districts. It is done by 
 
 rSKiRtiNG Formation* 
 
 NO. 4. 
 
124 CEMENTS AND CONCRETES 
 
 first laying a coat of coarse stuf? fair, and then scratch- 
 ing the surface with a coarse broom, after which a thin 
 coat of extra fat coarse stuff is laid, straightened with a 
 darby, and then trowelled and brushed. The second coat 
 must be laid while the first is green. This permits the 
 two coats to amalgamate better, and the surface to be 
 more easily worked and finished. 
 
 Stucco. — Stucco is an Italian term usually applied in 
 Italy to a superior species of external plastering. Ac- 
 cording to Vasari, Primaticcio ^'did the first stucchi ever 
 executed in France, and also the first frescos." In the 
 United States stucco is a somewhat indefinite term, used 
 loosely for various plastic mixtures in whose composi- 
 tion lime, plaster, or cements enter. Hydraulic lime 
 was formerly used for external stucco. Roman cement 
 was extensively used for stucco fronts during the first 
 half of the present century. Selenitic lime has some- 
 times been used for a similar purpose. These materials 
 are now entirely superseded by Portland cement. The 
 adoption in England of stucco externally to give brick 
 houses the appearance of stone is due to Robert Adam. 
 Its plastic nature enables it to adapt itself to most archi- 
 tectural purposes with very considerable decorative ef- 
 fects. The more general use of stone and the improve- 
 ments in terra cotta have so greatly decreased the use of 
 stucco for fronts, that stucco has become a synonym for 
 a sham, and its real usefulness for certain works and 
 places has been greatly overlooked. When properly pre- 
 pared and manipulated it makes excellent work, and in 
 the near future a large use may be predicted for its use. 
 
 Old Stucco. — It has already been shown that stucco 
 was largely employed by the ancients for plain and dec- 
 orative purposes. The temple of Apollo at Delos, and 
 even the first Parthenon under the ^gis of Pallas her- 
 
TERMS AND PROCESSES 125 
 
 self, were plastered with stucco. Vitruvius in his sev- 
 enth book mentions stucco under the name of opus al- 
 larium, sometimes written album opus. Tectorium opus 
 (from tector, a plasterer) was a name given by the Ro- 
 mans to a mortar used for plastering. According to 
 Vitruvius, Palladius, and Pliny, there seems to have been 
 a difference between tectorium opus and that called al- 
 barium or album opus. Vitruvius says tectorium was 
 composed of three coats of lime and sand, and three of 
 lime and marble. According to Winckelman, the united 
 thickness of these coats was not more than one inch. 
 The first coat was of common, but old, lime and sand, 
 and when it was nearly dry a second coat of lime was 
 laid, and on this drying a third coat of fine lime was laid 
 and made fair. The work was then laid with another 
 two coats of lime and marble, and finished with a coat 
 of fine marble powder. The marble mortar was fre- 
 quently beaten to render it tough and yet plastic, and 
 it was judged fit for use when it would no longer stick 
 to the trowel. When the lime mortar was dry, the mar- 
 ble mortar was laid, each successive coat of marble mor- 
 tar being laid before the preceding one was quite dry. 
 The first coat of marble mortar was composed of coarse 
 ground marble and old lime, the second of fine ground 
 marble and lime, the finishing coat being neat marble 
 ground to a fine powder, and laid before^the second coat 
 was dry, and worked with a wood float until the surface 
 was consolidated and straight. When dry it was pol- 
 ished with lime and chalk or with marble until like mar- 
 ble itself. Old stucco has been found so hard and highly 
 polished that it has been used for looking-glasses and 
 tables. In time it became hard and not liable to crack, 
 and formed an excellent ground for the painting with 
 which the Greeks and Romans decorated the walls of 
 
126 CEMENTS AND CONCRETES 
 
 their houses. According to Vitruvins, this painted plas- 
 ter could be detached without fear of injury, and de- 
 tached slabs were carried to Italy and inserted in the 
 walls of Roman houses. To prevent the cracking of the 
 work done on wood, it was strengthened by two layers 
 of reeds, one layer crossing the other at right angles. 
 To insure dryness, and allow the plaster to attain its 
 proper hardness, the walls were perforated at suitable 
 places. The tectorium was then decorated with brilliant 
 colors, which were applied on the last coat while it was 
 fresh; and to heighten the brilliancy and endurance of 
 the colors the surface was rubbed over vv^ith wax and 
 pure oil. When marble was used with lime in place of 
 sand it was termed martmoratum. The alburium or 
 album opus was what we term plaster or stucco. The 
 Greeks named tectorium and alburium, koniama and 
 kalachrisis. 
 
 Slabs of tectorium from the walls of Pompeii and Her- 
 culaneum are now in the Museum of Portici, and speci- 
 mens are also in the South Kensington Museum. In the 
 Museum of Practical Geology, London, there are several 
 pieces of old plaster, taken from the ruins of Pompeii, 
 some of which show that the decorative colors were not 
 applied a la fresco, but subsequent to the polishing. 
 Stucco and plaster are really two very different things. 
 Stucco has for its base carbonate of lime, generally burnt 
 limestone or chalk, with which putty- lime and coarse 
 stuff is mixed with sand, &c.^ and used for plastering 
 walls and ceilings. Plaster has for its base sulphate of 
 lime, being made from gypsum, and is used for cast 
 w^ork and gauging with lime putty, &c. The best kinds 
 of stucco will resist the action of weather, and can be 
 washed. Plaster, unless specially prepared or indurated, 
 perishes by exposure, at least in our climate, and cannot 
 
TERMS AND PROCESSES 
 
 127 
 
 be washed. Stucco is a superior kind of mortar, and it 
 may be used for plastering or for modelling. The ad- 
 mixture of various materials with lime and with plaster 
 to form stucco is referred to by many ancient writers. 
 Pliny mentions fig juice as being mixed with stucco. 
 The Egyptians mixed mud from the Nile with plaster 
 for some of their work. Elm bark and hot barley water 
 was mixed with the stucco for Justinian's Church of the 
 Baptist, Constantinople. We find bullocks' blood em- 
 ployed for this purpose as well in mortar for Rochester 
 Cathedral in the latter part of the ninth century. Bishop 
 Gundulph (1077-1108) is stated to have mixed blood 
 with lime to make it hard. Hot wax mixed with lime 
 was used at Rockingham Castle in 1280. White of eggs 
 and strong wort of salt were mixed with lime used for 
 Queen Eleanor's Cross at Charing Cross in 1300. Pitch 
 and wax were mixed with the lime used for Edward 
 II. 's works at Westminster in 1324. Mediaeval build- 
 ers habitually used beer, eggs, milk, sugar, gluten, &c., 
 for mixing with mortar for cathedrals. Frequent en- 
 tries found in the archives prove this. One reads, *^For 
 beer to mix with the mortar. ' ' Bess of Hardwicke 's ma- 
 sons used beer in their mortar, having to melt it in the 
 cold winter of her death. Old plaster is found to have 
 rye straw mixed with it for binding, and was very strong. 
 A brown substance somewhat like plaster, but full of 
 fibre, was in use in the sixteenth century. The accounts 
 for the repairs of the steeple of Newark Church in 1571 
 contain an entry, ^'6 strike of malt to make mortar to 
 blend with ye lyme and temper the same, and 350 eggs 
 to mix with it." During the building of the Duke of 
 Devonshire's house at Chiswick, the exterior of which 
 was plastered with stucco, the surrounding district was 
 impoverished for eggs and butter-milk to mix with the 
 
128 CEMENTS AND CONCRETES 
 
 stucco. Peter le Neve's mention of rye dough stands 
 not alone, as Sir Christopher Wren's '^Parentalia" * 
 (1750) records the use of '^marble meal" as the old and 
 still the modern way of stucco work in Italy. ''Marble 
 meal" simply meant marble dust ground as fine as meal. 
 This dust was used fo^ fine work. Sugar a,nd the gluten 
 of rice are used in Ceylon and India. The Chinese use 
 a rich unctuous earth in combination with lime. In some 
 parts of Prance urine was used with plaster in the six- 
 teenth century. Nearly all these admixtures are to re- 
 tard the setting, to allow more time for the manipulation 
 of the stuccos. Some are to accelerate the setting, and 
 some are to increase their ultimate hardness. 
 
 Many of the ancient buildings in various parts of the 
 universe, which were built of mud, clay, or sun-dried 
 bricks, had their surfaces decorated with hand-wrought 
 stucco. During explorations in Peru, South America, 
 Dr. Le Plongeon found some interesting specimens of 
 ancient plaster work in a number of the ruins of the 
 early Peruvian houses and cities, which date back to re- 
 mote antiquity. At Chenni Concha he found the frag- 
 ments of some ancient ornamental stucco on the adobe 
 (or clay-built) walls, covered with bas-relief decorative 
 designs, while the material is after many centuries still 
 in good preservation. The design and the execution are 
 of considerable merit, and it seems wonderful that a 
 people ordinarily held to be but little better than savages 
 could have conceived ornamentations so sesthetic, and 
 have executed them with such high technical ability. 
 
 Cav. M. Geggenheim, who has had much stucco work 
 done in the Palazzo Papadopoli and elsewhere, gives the 
 following formula for the stucco duro which is still used 
 in Venice: It is old stone lime, slaked for three years 
 at least, mixed with Carrara marble dust, ground as fine 
 
TERMS AND PROCESSES 
 
 129 
 
 as flour, into the consistency of paste. This of course 
 is for the finishing coat, the rough modelling being ex- 
 ecuted with a coarser material. 
 
 There are four kinds of so-called stuccos which are 
 used in this country. They are known as common, rough, 
 bastard, and trowelled. The methods of working these 
 species of plastering are embodied in the description of 
 three-coat work — in fact the only difference between 
 these stuccos and three-coat work lies in the setting coat, 
 the first-coating and floating being the same for all. 
 Some of the above terms are now only used by work- 
 men, and the use of stuccos is to a great extent super- 
 seded by Portland cement for exterior work, and Parian 
 and other white cements for interior work. The follow- 
 ing is a summary of the materials and methods used for 
 the various stuccos. 
 
 Common Stucco. — Common stucco was principally 
 used for exterior work. It is composed of 3 parts of 
 coarse sharp sand to 1 of hydraulic or grey lime, to which 
 a small portion of hair is added. It is laid in a similar 
 way to ordinary rendering in one coat, and the surface 
 finished with a hand float. 
 
 Bough Stucco. — This is generally used for plastering 
 churches, corridors, and entrance halls to imitate stone. 
 The work is floated with ordinary coarse stuff, and then 
 set with stuff composed of 3 parts of washed sharp sand 
 and 2 of grey lime putty, not chalk. This is laid with 
 a trowel, and then ruled in with a straight edge until 
 the surface is full and fair. After this it is scoured 
 with an ordinary hand float, and finished with a ^^felt 
 float,'' not to raise the grit, but to keep it down. The 
 felt float is an ordinary hand float with an unplaned 
 sole, on which a felt sole, about 14 i^^h thick, is fixed 
 with gauged plaster. This tool before using generally 
 
130 
 
 CEMENTS AND CONCRETES 
 
 requires to be riiDbeci on a str^aight stone to obtain a uni- 
 form face. Great care must be exercised when laying 
 and finishing the surface, so that no joints are shown, 
 or else they w^ill never dry out. AVhen wanted to repre- 
 sent ashlar masonry, the surface is set out with lines to 
 the size of the required stones, and then the lines are 
 indented to form the joints with a jointer or the ring 
 end of a key. The grain of the stone can be better imi- 
 tated by patting the surface with the hand float as a 
 finish. The staining of stucco to represent the color of 
 stone is done by diluting sulphuric acid (oil of vitriol) 
 with water, and mixing with it the liquid ochres and 
 other colors to the required tints. The setting stuff may 
 also be mixed with the ochres before using. A small por- 
 tion of the colored stuff should be dried to ascertain the 
 tints before laying the whole surface. 
 
 Bastard Stucco is somewhat better in quality than or- 
 dinary setting. The final coat is composed of 2^2 parts 
 of washed sharp sand and 2 parts of chalk lime putty. 
 It is laid in two coats with a skimming float, scoured up 
 once and then trowelled oft' and brushed. 
 
 Trowelled Stucco is generally used for work that has 
 to be subsequently painted. The stuff' for the finishing 
 coat is composed of fram 2^ to 3 parts of washed sharp 
 sand to 2 parts of chalk lime putty. The sand is not so 
 fine as that used for ordinary setting, being washed 
 through a sieve having about 12 mesh to the inch. The 
 stuff is laid on^ and then traversed with a floating rule 
 in all directions, up and down, across and diagonally. 
 The surface is then scoured up without water, and after 
 a rest to admit of shrinkage, the surface is scoured up 
 three times with water ; the trowel to immediately follow 
 the third scouring up. This trowelling is continued 
 until the work becomes so hard that no impression can 
 
TERMS AND PROCESSES 
 
 131 
 
 be made on the surface; it is then brushed off with a 
 soft damp brush (not wet), first horizontally, then diag- 
 onally, and finally perpendicularly, leaving a brilliant 
 face. When dry, the gloss goes off, and leaves a fine 
 surface for paint. 
 
 Colored Shtcco. — The Italians execute lime stuccos in 
 colors, mixing in the lime various oxides — i. e., blacks 
 are obtained by using forge ashes containing particles of 
 iron; pearl greys are made by mixing ashes with the 
 marble; greens are obtained by using green enamel, with 
 a large proportion of marble powder, worked up with 
 lime-water; browns by mixing ashes with the lime and 
 marble in proportions varying with the tints desired; 
 reds by using litharge, or the red oxide of lead; blues 
 by r^iixing 2 parts of marble powder and 1 of lime, and 
 1/4 of oxide, or carbonate of copper. Stucco may also 
 be colored with the same materials as described for 
 colored setting, also for sgraffito and concrete. 
 
 MetJiod of Wo7^king Keen's^ Parian, and Martinis 
 Cements. — When describing the technique or practical 
 manipulation of Parian and the other white cements 
 which have been invented in the nineteenth century, it 
 is only natural that one should feel animated by a pecu- 
 liar pleasure, because in these cements, our industry, 
 aided by modern science, has, as far as is known, 
 equalled, if not excelled, an^^thing of the kind produced 
 by the ancients, tested by any experiment, whether for 
 strength, solidity, or durability. With these a great sav- 
 ing in time can be effected, as work can be begun and 
 finished in one operation, without waiting for the differ- 
 ent coats to dry, as in ordinary lime plastering. For 
 sanitary purposes they are unequalled. This, combined 
 with their chemical properties, which enables them to be 
 painted, papered, or distempered as soon as finished, 
 
132 CEMENTS AND CONCRETES 
 
 renders them the most valuable of all plastering materials 
 in this go-ahead age. They are free-working, sanitary, 
 durable, and practically fireproof. They are the very 
 best materials for plastering walls, dadoes, or in similar 
 exposed positions. For skirtings they are invaluable, 
 as they offer an effectual resistance to fire, vermin, and 
 dust. When properly manipulated, they can be worked 
 to a porcelain-like surface. They are nearly perfection, 
 and constitute perfect plasters for most interior work. 
 Their only drawback is that they will not resist the ef- 
 fects of moisture. It is therefore imperative that damp 
 walls should be floated with Portland cement, where 
 a white cement finish is desirable. By the aid of the 
 hard and sanitary white cements plastering has become 
 a tangible reality, instead of a comparative makeshift, 
 which it has hitherto been. The object aimed at in the 
 invention of white cements for internal use is to pro- 
 duce a material of which plaster is the base, which shall 
 set sufficiently slow to be easily manipulated, become 
 dense, hard, non-porous, and may be painted as soon as 
 finished. Before the introduction of these cements, all 
 making good, as it is technically called (i. e., patching 
 holes in old plaster work), used to be done with neat 
 plaster, plaster and sand, or lime gauged with plaster. 
 Keen's was first introduced, then Parian, and lastly 
 Martin 's. Parian being most in demand, claims priority 
 in description. Parian and other white cements are uni- 
 formly reliable in quality, but through the rapacity of 
 some contractors the cements are often adulterated with 
 plaster to lower the cost, and hasten their setting. This 
 adulteration causes the cement to swell^ and in many in- 
 stances to peel or fall off. Even if it does adhere, it 
 never attains its due hardness, and thus is no better than 
 ordinary plaster. Unfortunately adulteration brings 
 
TERMS AND PROCESSES 
 
 133 
 
 discredit on the cement and the trade. The only remedy 
 is proper supervision by a plasterer who possesses a thor- 
 ough knowledge of plastic materials and the methods of 
 using them. If plasterers were awarded certificates of 
 competency, adulteration would be prevented, and good 
 work ensured. Honest employers would find this bene- 
 ficial, for scampers can only thrive where there is a lack 
 of knowledge of the technique peculiar to plastering, 
 and which only plasterers of experience really possess. 
 
 In using Parian cement on lath-work, exceptional care 
 must be observed that all the lath nails be galvanized, 
 or painted over, or coated with shellac, to prevent rust. 
 For this same reason all nails used for plumbing and 
 levelling purposes must be extracted after the screeds 
 are set. For first-coating and floating ceilings with this 
 material, the proportions for best work are 1 part of 
 cement to 2 of clean sharp sand, adding about the same 
 quantity of hair as for lime plaster. Walls are generally 
 floated with Portland cement in the proportion of 1 part 
 of cement to 3 of sand, and finished with neat Parian. 
 This system is adopted as a matter of economy, as Port- 
 land cement is cheaper than Parian; and where time is 
 no particular object, makes equally as good work. For 
 walls intended to be painted or polished immediately, it 
 is necessary to mix the materials in the same proportion 
 as for ceilings, with the difference that more sand may 
 be used — say 2 parts of cement to 5 of sand. The rea- 
 son for this is, that when floated with Portland, and 
 finished with Parian an efflorescence invariably appears 
 on the finished surface, and until it has time to dry out, 
 it is inimical to successful painting or polishing. Gaug- 
 ing is an important point; it must be carefully and 
 quickly done to insure success and obtain the full 
 strength of the cement. For first-coating or floating 
 
134 CEMENTS AND CONCRETES 
 
 ceilings, empty a sackful, or half a sack according to 
 requirements, in a clean banker; then add the sand in 
 the proportions already given, and thoroughly mix the 
 cement and sand while yet dry ; then form a ring, and 
 pour in the water, taking care not to pour in too much, 
 as it must be gauged, and used as stiff as practicable. 
 There will be no difficulty in thus using it, as it will take 
 some hours to set, according to the season of the year 
 (quicker in summer than in winter). When the , water 
 is in, add the hair (which must previously be well beaten 
 and soaked), and gauge the whole mass together. Then 
 begin the first coating, scratch it in the usual manner, 
 and so on, until the whole ceiling is first-coated. It 
 should stand for twenty hours before starting to float. 
 Hair is generally omitted for common work, or where 
 the laths are close. 
 
 Parian cement ceilings should be dead level, and have 
 a uniform and straight surface; therefore the screeds 
 should be levelled, made narrow, and the sides cut square, 
 and when firm the whole ceiling should be ruled in with 
 a floating rule, , sufficiently long to reach from screed to 
 screed. The floating stuff is gauged moderately stiff, 
 and laid diagonally across the line of laths, so as not to 
 spring the lath-work, or disturb the key of the first-coat- 
 ing. After the ceiling has been laid, the floating rule is 
 applied, a man holding each end (and one at the center 
 if extra long). It is then drawn gently and steadily 
 along, filling up hollow places, until the whole surface 
 is straight and true. When the surface is firm, it is 
 brushed with a coarse broom to form a key for the finish- 
 ing coat. If there is a Parian cement cornice to be run, 
 the usual mode for plaster and putty is adopted for the 
 running rules. The screeds should be made sufficiently 
 smooth to run on, without forming an extra thickness or 
 
TERMS AND PROCESSES 135 
 
 traversing screed. The cornice is roughed out with the 
 same kind of material as used for the floating, employ- 
 ing a muffled running mould for running the rough stuff. 
 It may not be practical to rough out all the cornice at 
 once, as this stuff does not set quick, therefore it may be 
 necessary to leave it for a time until the stuff stiffens. 
 No definite directions can be laid down in this matter, as 
 the suction is greater in some seasons and rooms than in 
 others. A little extra hair, also extra stiff gauging, is of 
 service to make the stuff cling together, thus allowing 
 the work to be roughed out sooner. The running moulds 
 must be made of strong zinc or copper (no iron to be 
 used on any account). Where the work is in cornices, 
 skirtings, achitraves, &c., the mould should be muf- 
 fled with a zinc or copper plate. If there is only a small 
 quantity to be run, a plaster muffle may suffice. After 
 the cornice is roughed out, it is finished with neat Parian, 
 and then the mitres formed in the usual way. 
 
 In preparing to finish a large space (ceilings or walls) 
 it is absolutely necessary that no more should be laid 
 than can be finished the same day, therefore as many 
 ihen should be put on the job as will accomplish that 
 object, as no sign of a joint should be shown on the sur- 
 face. In the case of large or high walls, the scaffold 
 should be so arranged that the men can work the whole 
 wall from the cornice down to the skirting in one opera- 
 tion. If a wooden skirting has to be subsequently fixed, 
 one end of the rule bears on the fixing grounds ; but if a 
 Parian skirting or base is specified, it is generally run 
 before the walls are finished, and allowed to get thor- 
 oughly hard, so as to bear the end of the rule used for 
 the finishing coat. The lower end of the rule is cut to 
 fit the upper member of the skirting. Another way is 
 to nail a board onto the end of the rule, so that it bears 
 
136 CEMENTS AND CONCRETES 
 
 well on the plain plinth and clears the members of the 
 skirting. The cornice screed must be keyed with a drag 
 before the finishing coat is laid. For large cornices it 
 is often desirable to traverse the running screeds. In 
 this case they must be cut down to the floating, leaving 
 only the margin formed by the running mould. This 
 margin forms a bearing for the top end of the rule. In 
 some instances a special margin or bearing is cut at the 
 outer members of running moulds for cornices and skirt- 
 ings, and when run they form a bearing for the floating 
 rules. 
 
 When ready for the finishing coat, empty as much as 
 required of neat Parian cement into a clean banker, and 
 gauge it smooth and stiff; then soften it down to the 
 desired consistency, always bearing in mind not to make 
 it too soft, as sloppy stuff for any purpose is ever to 
 be avoided. The gauging should be so arranged that 
 when one batch is in use another one is ready, which 
 prevents delay in laying the whole space, thereby ensur- 
 ing similarity of texture and results. The thickness of 
 the finishing coat should not exceed % inch. "When 
 there are about a dozen yards laid, two men must follow 
 on and rule the surface fair from screed to screed on 
 ceilings, and top and bottom on walls. The greatest pos- 
 sible care must be observed that the whole surface is 
 ruled in fair and uniform, otherwise the surface will be 
 imperfect. 
 
 White cements, owing to the suction of the walls or 
 ceilings, have a tendency to shrink more or less, accord- 
 ing to the stiffness of the gauge and the section, there- 
 fore they must be ruled in twice. When the coat already 
 laid is firm, then some more cement, gauged softer than 
 the first, should be laid thinly all over, and ruled as care- 
 fully as before. Having done this the whole surface is 
 
TERMS AND PROCESSES 137 
 
 nearly ready for scouring;. It is allowed to stand for an 
 hour or two, or until quite firm. If scouring is at- 
 tempted before, it will work into hollows, and a bad job 
 will be the result. If the finger cannot make an im- 
 pression upon it easily, it is sufficiently firm, and then 
 all hands begin to scour the work, using very little water, 
 and working the hand float with a circular motion. The 
 hand float must not be worked long on one spot, but kept 
 moving over all the surface within reach, and working 
 back again until the whole surface has an even grain or 
 texture. The whole work must be scoured twice to bring 
 it up to a fine solid surface. When there is about half 
 of the wall scoured, two or more plasterers can continue 
 the scouring, and the remainder of the men go back and 
 start the trowelling. This must be done with good long 
 strokes, using very little water, and taking care not to 
 dent the surface with the trowel. After the men have 
 finished the scouring, they come back and start at the 
 beginning with the second ''trowelling off or final 
 trowelling. This is done both vertically and horizon- 
 tally, and when the work begins to harden, the trowel is 
 laid on the near edge and worked with a cutting motion 
 downwards. This is repeated all over the work until 
 every particle of glut or ' ' fat ' ' is cleared off the surface. 
 If the work has to be polished, the cutting action with 
 the trowel must be followed with a 9-inch joint rule and 
 a damp brush, but the work must be hard before this 
 last can be attempted. Work carried out on the above 
 plan v\^ill reflect credit on the material and the workers. 
 The same methods apply equally to Keen 's and Martin 's. 
 Martin's is preferred by some plasterers for running 
 cornices because it sets quicker than Keen's. For plain 
 surfaces, such as w^alls and ceilings, it sets too quick? 
 and has to be ''killed" (that is working the stuff again 
 
138 CEMENTS AND CONCRETES 
 
 and again with water until the initial set is stopped or 
 ''dead") before it can be conveniently used. Although 
 it finally sets fairly hard, it never attains the same de- 
 gree of hardness as Keen's or Parian. 
 
 Several other white cements and plasters have been 
 introduced during the last two decades. They will be 
 noticed later on. 
 
 White Cement Efflorescence. — For work that has to 
 be painted, care must be exercised in the selection and \ 
 manipulation of the materials used for the plaster work, 
 so as to avoid as far as possible subsequent efflorescence. 
 In the manufacture of Keen's, Parian, and Martin's 
 cements, Keen's original process is doubtless the best. 
 It requires, however, great care in carrying out, the 
 chemicals used and temperature employed requiring to 
 be suited to the peculiarities of the gypsum. The de- 
 sired result is extreme hardness, combined with non-ef- 
 florescence. Keen's cement is practically non-efflores- 
 cent, as if applied on a dry wall containing no soluble 
 salt, in itself there would be no efflorescence that would 
 spoil paint. Perhaps one should not say that Keen's 
 cement, or at least all brands of it, are absolutely non- 
 efflorescent, as there is generally a powdery coating comes 
 on the surface, just enough to whiten a colored hand- 
 kerchief, something like the coat of puff powder used 
 on some female faces. On no account should Keen's 
 cement be used" on walls as a preventive of damp, as 
 it is useless for this purpose. If used on a damp wall, 
 or in places exposed to atmospheric influences, it will 
 effloresce more or less, as its base is gypsum, which al- 
 ways remains soluble. In damp situations the walls 
 should be rendered or floated in Portland cement before 
 the finishing coat of Keen's cement is laid. The same 
 remarks apply to Parian and Martin's cements. The 
 
TERMS AND PROCESSES 
 
 139 
 
 Keen's cement manufactured by Hunkin's and Willis, 
 St. Louis, Mo., is practically non-efflorescent. 
 
 Cornice Brackets. — Brackets or cores are used to de- 
 crease the amount of materials and weight, and also to 
 form a foundation and support for cornice or other 
 mouldings. For large exterior work they are generally 
 formed with stone, and for small work bricks, tiles, or 
 slates are used, which are built into the walls as the 
 work proceeds, and roughly fashioned to an approxima- 
 tion to the profile of the intended cornice or other mould- 
 ing. For interior work the brackets are sometimes con- 
 structed with metal lathing, also with spikes and tar 
 bands, termed ' ' spike and rope brackets, ' ' but the oldest 
 and most general way for cornice mouldings are "lath 
 brackets.'' The "brackets" on which the laths are sub- 
 sequently nailed are cut out of boards from % inch to 
 11/2 inches thick, according to the size and form of the 
 cornice. The section of the brackets should be about 1 
 inch less than the profile of the proposed cornice to allow 
 for a thickness of lath and plaster. The thickness of the 
 plaster should not exceed 1 inch, or be less than I/2 inch. 
 If too thick it is a waste of materials, and the undue 
 weight is apt to pull or spring the laths from the brack- 
 ets, and if too thin the stuff is apt to crack. The profile 
 of the bracket need not follow closely that of the cor- 
 nice, but a general or approximate outline of the most 
 salient members followed. Any thin projecting mem- 
 bers may be subsequently strengthened by means of 
 projecting nails and tar-strings similar to a spike and 
 rope bracket ; also by using extra hair and plaster in the 
 roughing out stuff. Brackets for enriched cornices re- 
 quire special notice. Unless a due allowance is made for 
 sinkings for the thickness of the cast enrichments and 
 a correct form of bed, there will be unnecessary trouble 
 
140 CEMENTS AND CONCRETES 
 
 in cutting and hacking the lath work and brackets when 
 the running of the cornice is commenced. There is a 
 marked difference between the section of a running 
 mould for an enriched cornice and that of a plain cor- 
 nice, even if the profile of both are the same. To avoid 
 mistakes of this nature the plasterer should supply the 
 carpenter with a section of the brackets, taken after the 
 bed of the enrichments are set out on the tracing of the 
 proposed cornice. 
 
 Skeleton brackets is a term applied to a method some- 
 times used for coring out angles, to save materials where 
 there are no brackets, and for small mouldings. This is 
 effected by placing the mould in position and then fitting 
 a piece of lath in a vertical position, and allowing a space 
 of about % inch from the face of the lath to the nearest 
 part or most prominent member of the mould. A mark 
 is then made on the ceiling and wall at the top and bot- 
 tom of the lath. Similar marks are made at the other 
 end of the wall and ceiling, and then a line is struck on 
 the marks, from end to end of the ceiling and wall, by 
 means of a chalk line. The stuff which forms the parts 
 of the screeds inside the lines is cut away, dusted, wetted, 
 and then a narrow strip of gauged coarse stuff is laid 
 along the lines where the ceiling and wall screeds are 
 cut, and the laths which have been previously cut to the 
 length of the first or trial one are fixed vertically into 
 the gauged stuff, keeping them apart as in ordinary lath- 
 ing. They are further secured by laying strips of 
 gauged stuff on the outward surfaces at the top and bot- 
 tom ends. After the stuff is set, the cornice is run in 
 the usual way. 
 
 Cornices. — Cornices, either plain or enriched, are 
 formed with a running mould cut to the profile of the 
 intended cornice. The formation of cornices consists of 
 
TERMS AND PROCESSES 
 
 141 
 
 constructing the mould, making the running screeds, 
 fixing the running rules, running the cornice and mitring 
 the angles, with the addition of fixing the cast ornament 
 for enriched cornices. Cornices were formerly run in 
 short lengths and in sections. Two, three, and even four 
 moulds were employed for cornices that are now done 
 with one. For large cornices, where the mould is diffi- 
 cult or sluggish to run, or apt to jump, the bearings 
 should be greased or brushed with soap or dusted with 
 powdered black lead or French chalk. Running moulds 
 are run in some places with the left hand, from left to 
 right, and the mould plates are also fixed to the left hand 
 side, having the bevelled part of the stock to the right 
 or running side. In America the plates are fixed oh the 
 running or right side, and the mould is run with the 
 right hand from right to left. The way of running from 
 left to right with the left hand allows more freedom, 
 especially in small mouldings, for the right or trowel 
 hand to assist in feeding the cornice with the stuff that 
 gathers on the mould. It also gives more freedom to 
 his partner who is laying on the stuff, as with the hawk 
 in his left hand and his trowel in his right he is able to 
 work in a natural position, namely, from left to right, as 
 in laying coarse or setting stuff on w^alls, whereas, when 
 the mould is run with the right hand, and from right to 
 left, the worker has not so much power or freedom in 
 assisting to feed the mould with his left hand. His part- 
 ner, who is laying the gauged stuff, is working back- 
 handed, and if using a laying trowel, can only work from 
 its heel instead of from the point as is usual; and if 
 using the large gauging trowel for laying on every 
 trowelful used must be put on with a backhanded turn. 
 It may be a matter of opinion as to which method is 
 better, and depends a good deal upon which way the man 
 
142 CEMENTS AND CONCRETES 
 
 has been taught, but the manner of running the mould 
 and laying on of stuff from left to right, the same as 
 in writing, is the most natural. Running screeds are 
 used as bearings for running moulds. They are com- 
 posed of gauged stuff, and made straight with floating 
 rules. Screeds for cornices are formed with -raw or with 
 gauged coarse stuff. They are next traversed. The 
 line of the screed is got by placing the running mould 
 in its true position or at one end of the wall, and mak- 
 ing a mark on the floating screeds at the outside of the 
 nib and the bottom of the slipper. The same operation 
 is repeated at the other end of the wall, and a continuous 
 line from one mark to the other made on the ceiling wall 
 by means of a chalk line. A narrow strip of gauged 
 putty and plaster is now laid on the lines by one man, 
 while his partner follows on with a traversing rule, work- 
 ing the rule with a slanting motion, and moving back- 
 wards and forwards until the screed is just and true. 
 Where the walls are very long, running screeds are done 
 by two men working a long straight edge or floating 
 rule. The screed is afterwards further fined by draw- 
 ing a cross-grained hand float three or four times over 
 it in a longitudinal direction. Where the coarse stuff 
 screeds are not gauged, the running screeds are made in 
 a similar manner, but the putty is mixed with an equal 
 proportion of setting stuff before gauging. The addi- 
 tion of sand gives more resisting power to the wear of 
 the nib and slipper of the running mould. The run- 
 ning screeds are made on the long sides of the room, 
 and when set they give a bearing for the end screed in 
 its true position at one end of the wall. 
 
 Fixing the running rules is the next operation. This 
 is done by placing the running mould in its true position 
 at one end of the wall, taking care that the mould is 
 
142 ( 
 
 has been ta 
 and laying 
 in writing, 
 used as hei 
 posed of gi 
 rules. Scr( 
 gauged coa 
 line of the 
 in its true 
 ing a mark 
 nib and thi 
 is repeated 
 line from o 
 by means c 
 putty and } 
 while his pa. 
 ing the ruh 
 w^ards and 
 "Where the i 
 by two mei 
 rule. The i 
 ing a cross- 
 it in a lonfj 
 screeds are p 
 a similar ml 
 proportion t 
 tion of san| 
 the nib anc 
 ning screed' 
 and when s 
 its true pos* -^- 
 
 Fixing th 
 is done by i 
 at one end 
 
TERMS AND PROCESSES 143 
 
 square/' that is, that the perpendicular parts of mem- 
 bers are plumb with the wall. This may be tested with 
 a plumb bob hanging over the side of the mould, and by 
 seeing that the line of the plumb bob hangs properly over 
 a marked line which has been previously made by squar- 
 ing off from a square member or by extending a parallel 
 line from an upright member of the mould. When the 
 mould is plumb and square, a mark is made on the ceil- 
 j ing screed at the outside part of the nib, and another 
 made on the wall screed at the bottom of the slipper. 
 The same operation is repeated at the other end of the 
 wall, and the line extended from mark to mark by using 
 a chalk line. The line in this case should be blackened 
 by means of charcoal or burnt stick, as it shows better 
 than a white line on the light-colored screeds. As the 
 chalk line may sway when striking the wall line, this 
 line should not be trusted for fixing the running rules 
 to. This may be proved by placing the mould every 3 
 or 4 feet apart in the length of the wall, taking care to 
 keep the outer edge of the nib at the ceiling line; then 
 marking with a gauging trow^el at the bottom of the slip- 
 per. Nails are now driven into each of these marks and 
 left projecting as a guide for fixing the running rules. 
 The running rules should not be less than 21/2 inches 
 wide or more than 31/^ inches wide and i/^ inch thick, 
 being made out of good redwood or pine planed on both 
 sides and edges. The rules are now fixed into the wall 
 screed either by nailing them to the studs or into the 
 joints of the walls. They are also fixed by wetting one 
 face of the rule and laying dabs of gauged putty and 
 plaster about two feet 6 inches apart. The rules are 
 now pressed on the wall while the stuff is soft, taking 
 care not to force the guide nails out of position. The 
 rules are further secured by laying patches of gauged 
 
144 CEMENTS AND CONCRETES 
 
 stuff underneath the rule partly on the wall and rule 
 where the dabs are. "When the rules are fixed by nail- 
 ing, it is apt to crack the first-coat of floating, and the 
 joints of the wall are not always easily found. The 
 coarse stuff for the first-coat of cornice brackets should 
 be extra haired and carefully scratched to give a strong 
 foundation for the following coats of gauged stuff, which 
 in many instances is extra thick at bold or projecting 
 parts of the mouldings. 
 
 For large moulding and wire lathing it is best to leave 
 the brackets uncoated when first coating the general 
 work until the cornice running is commenced, and then 
 to rough out the whole cornice from the lath work with 
 gauged coarse stuff. This gives uniform suction and 
 strength. If the brackets are lathed with wood, they 
 should be first-coated with gauged coarse stuff and 
 scratched before the screeds are formed, so as to allow 
 time for the lath work to settle before the mouldings 
 are roughed out. Weak laths frequently twist by moist- 
 ure from the first-coating, and gradually settle or re- 
 sume their original form during the drying of the first- 
 coating. Leaving the lathed brackets uncoated also 
 forms a vent for the moisture from the wall and ceiling 
 first-coating, thus allowing it to dry sooner. The coarse 
 stuff for roughing out the cornice should be gauged uni- 
 formly in strength and consistency, as unequal gauging 
 tends to cause unequal swelling in the material, conse- 
 quently the mould is more difficult to run true. The 
 coarse stuff should be laid regular in thickness, taking 
 care to gradually build up and form all thick parts and 
 projecting members with the trowel to prevent the stuff 
 from dropping and the mould from dragging it off, as 
 generally happens if the stuff is laid in thick and irregu- 
 lar coats. When roughing out large mouldings with 
 
TERMS AND PROCESSES 145 
 
 coarse stuff, the members of the mitres should also be 
 filled in and ruled fair before the running with gauged 
 putty is commenced, because when mitring, it will be 
 more easily and quickly done, materials will be saved, 
 and when finished, the whole will be more uniform in 
 color. 
 
 When all the mouldings are roughed out, the plaster 
 muffle or muffle plate, as the case may be, is taken off, 
 and the running with fine gauged putty commenced. 
 The gauge board and all tools should now be cleaned to 
 free them from grit. A ring of putty is formed on the 
 gauge board, leaving the bottom of the board clear; 
 water is put in the ring and the plaster quickly and 
 evenly sprinkled over the water, taking care not to sprin- 
 kle it on the putty ring. The plaster and water are 
 mixed together by stirring with the point of a trowel. 
 The putty is then quickly mixed with the gauged plaster 
 by using the trowel and turning it over with the hawk. 
 It is put on with a large gauging trowel, or if the mem- 
 bers are large, with the laying trowel, following the form 
 of the mouldings. The mould is then run along by one 
 man, who also feeds the moulding with any stuff that 
 may gather on the side of the running mould. This 
 operation is continued until all the members of the 
 mouldings are filled out. A thin gauge of fine putty, 
 having less plaster than the previous gauges, is lightly 
 drawn over with a trowel, or brushed over the flat mom- 
 bers, and thrown with a brush for small or dry mem- 
 bers. This mould is then quickly and steadily run along 
 the cornice from beginning to end and finished. If the 
 moulding is extra large in girth, or a long length of 
 moulding has to be run, extra men are required to lay 
 the stuff, while two may be necessary to run the mould. 
 
146 CEMENTS AND CONCEETES 
 
 When running small mouldings, say of 10 or 12 inches 
 in girth, one man can run and feed the mould while his 
 partner is laying on. When all the mouldings are run 
 around, the running rules are taken down, the screeds 
 cleaned and scraped, and any holes or defects caused 
 by nails or patches used for the rules made good by fill- 
 ing up with gauged putty. If soap, black lead, or any 
 other materials already mentioned are used to aid and 
 ease the running of the mould, they should be scraped 
 ofE with a drag as soon as the cornice is run off, other- 
 wise they will prevent the finishing coats for wall and 
 ceiling from adhering to those parts. 
 
 To Set Out and Construct Corinthian Entablature. — 
 To enable the plasterer to set out a full size or working 
 drawing from the architect's design, also to comprehend 
 the cornice and the architrave, which are sometimes used 
 alone or as separate mouldings, their proportions with 
 that of the entire entablature are given. The entabla- 
 ture and the details of the enrichments of the coffers 
 and modillions are shown on plate. 
 
 The whole height of the entablature is divided into 
 ten parts, giving three to the architrave, and three to 
 the frieze, and four to the cornice, as shown by the first 
 upright scale at Fig. 1. This figure shows the combined 
 section and elevation of the entablature. The height 
 of the architrave is subdivided into five parts to form 
 its members, as shown by the second upright scale. 
 Projection is taken from the lower fascia, and is equal 
 to one-fourth part of its height. As the cornice of the 
 Corinthian order is frequently used alone as a separate 
 moulding, an enlarged view with figured details is given, 
 see illustration Fig. 4. It is necessary that the details 
 of the cornice should be mastered before proceeding with 
 the entablature. See Plate 1, 
 
TERMS AND PROCESSES 147 
 
 With regards to the enrichments of the entablature, 
 as shown in Fig. 1, the whole must be set out and so dis- 
 posed and arranged that the centre of each will be in line 
 with each other, or, in other words, that they are regu- 
 larly disposed perpendicularly above each other, as 
 shown from A to B (Fig. 1) where it will be seen that 
 the centres of the modillion, dentil, egg, and other bed- 
 mould enrichments are all in one perpendicular line. 
 Enrichments set out in this v/ay are said, in plasterers' 
 parlance, to ^ ' principle. ' ' Nothing is more careless, con- 
 fused, and unseemly than to distribute them without 
 any order or principle, as they are in many buildings. 
 The centre' of an egg answers in some places of the cor- 
 nice to- the edge of a dentil, in some to the centre, and 
 in others to the space between, all the rest of the enrich- 
 ments being distributed in the same slovenly artless 
 manner. The larger parts must regulate the smaller. 
 All the enrichments in entablatures are governed by the 
 modillions, or mutales, and distribution of these must 
 depend on the interval of the columns, and to be so dis- 
 posed that one of them may come directly over the centre 
 of the column, as shown in the present example at 0 
 (Fig. 2), the axis of each column. 
 
 The enrichments must partake of the character of the 
 order they enrich. "When the frieze is enriched, and the 
 enrichment may be characteristic of the order, or it may 
 serve to indicate the use of the building, the rank, quali- 
 ties, profession, and achievements of the owner. Hav- 
 ing set out the profile and the enrichments, making the 
 running mould and the running mouldings now claims 
 attention. For large work the cornice and the archi- 
 trave are run separately, the cornice being run from the 
 slipper screed made on the frieze and a nib screed, and 
 the architrave from a slipper screed made on the wall 
 
148 CEMENTS AND CONCRETES 
 
 and a nib screed made on the frieze. Sections of the 
 cornice and architrave running moulds are shown at 
 Fig. 4. 
 
 It may be here remarked that the nib and slipper 
 bearings of the cornice and architrave running moulds 
 are made for work on ceilings and walls; but if the 
 entablature projects or is independent, and supported by 
 columns, the nib of the cornice mould must be cut so 
 as to bear and run on a nib running rule fixed on the 
 weathering of the cornice, and the slipper of the archi- 
 trave running mould cut so as to bear and run on a 
 running rule fixed on the soffit of the architrave. The 
 frieze, if plain, is set by hand; and if enriched, a bed 
 for the enrichment must be made by running a small 
 part of the bed at the top and bottom of the frieze when 
 running the cornice and architrave mouldings. In this 
 case the screed on the frieze must be set back to allow 
 for the plate or ground of the ornament, and the nibs 
 and slippers of the running moulds extended at these 
 parts. In setting out the mould plates an allowance 
 must be made for the bed of the various enrichments, as 
 previously described. 
 
 The profiles of the three largest enrichments are indi- 
 cated by the dotted lines. The angles of the beds of 
 these enrichments are splayed, as shown, to save fine 
 plaster used for the cast work. This also strengthens 
 the top member of the architrave while it is being run. 
 It will be seen that an in-dentil is used in this cornice, 
 as shown by the dotted line at 1 on the elevation. This 
 is the space between the face or main dentils. The in- 
 dentil is run with the mouldings, and the dentils are cast 
 and planted. The in-dentil and the dentil may also be 
 cast together in short lengths, and then planted. In 
 this case the running mould must be cut to form a bed 
 
TERMS AND PROCESSES 
 
 149 
 
 for the combined dentils, as indicated by the dotted line 
 on the outside of the section of the running mould. The 
 dotted line on the section of the running mould shows 
 the section of the main dentil. In some examples the 
 external angles of the bed of the dentils are filled in with 
 an ornament fashioned like a cone or pineapple, instead 
 of using an angle dentil. An enlarged view of this class 
 of ornament fixed in position is shown at Fig. 11. The 
 bed of the small enrichments is made square as shown. 
 
 When setting out the mould plate, the profile of the 
 soffit of the corona must be taken through the centre of 
 the sunk panel, as shov/n by the shaded part at Fig. 3, 
 thus forming the raised part of the mould as shown at 
 Fig. 4. 
 
 The most intricate part in the construction of a Cor- 
 inthian cornice consists in the formation of the coffers, 
 as shown at Fig. 2. This is a plan of the cornice at an 
 external angle. F is a coffer, and M is a modillion or 
 ''block," as it is commonly called. The coffer consists 
 of a sunk panel, with an enrichment on the four sides, 
 and a rose or patera in the centre as shown. A section 
 of the coffer is showni at Fig. 3. The coffers are formed 
 by fixing a ''style," as from S to S (including the side 
 enrichments), on the sunk panel, so as to connect the 
 two run plain sides of the soffit and form two sides of 
 the coffer. The lines in the front and back of S and 
 S indicate the joints of the style before they are stopped. 
 It will be understood that the style is fixed before the 
 block is fixed. A plan of the complete style is shown at 
 Fig. 5. When making the model of the style, the side 
 enrichments must be set out mitred and fixed on the 
 plain part of the style, and a perforation made in the 
 centre to act as a key for the fixing stuff used when 
 fixing the block. A mark must also be made in the cen- 
 
150 CEMENTS AND CONCRETES 
 
 tre of the front of the style to act as a guide when fixing 
 the styles. The model of the style is moulded in wax, 
 taking care to splay the back and front edges and the 
 centre perforation, also the mitres of the enrichments, 
 to allow the mould to draw in one piece. These parts 
 are trimmed square after the styles are cast. Having 
 fixed two styles, the front and back parts of the coffer 
 enrichments, as shown at Figs. 6 and 7, are fixed; then 
 the patera (Fig. 8) is fixed; and then the joints of the 
 styles are stopped, which completes the coffer. This 
 done, the block (Fig. 9) is fixed, and then the small en- 
 richment (Fig. 10) is fixed, thus completing a part of 
 the soffit of the corona. The other parts are of course 
 made and fixed in a similar way, but the positions of 
 the coffers and blocks must be set out on the whole 
 length of the cornice before the fixing is commenced. 
 
 Setting out coffers and blocks is a simple matter, yet 
 it requires care to ensure accuracy. First fix a coffer 
 and a block in each mitre, as shown at the external 
 mitre (Fig. 2) ; then from the centres of these blocks set 
 out the whole length of the cornice. This is best done by 
 measuring the full length of the cornice from the mitre 
 blocks, and dividing the total by the combined width of 
 one modillion and a coffer, and if there is no remainder, 
 the combined width is marked on the soffit ; but if there 
 are a few inches over, they are divided among the given 
 number of blocks. The marks are proved by going over 
 them with a compass or a wood gauge. When the exact 
 positions of the centres of each coffer with the block is 
 ascertained, the marks are extended across the corona 
 and down the plain member on which the back end of 
 the block rests on by the aid of a square. These ex- 
 tended marks or lines give the centres for fixing the 
 styles of the coffei's and the blocks. Fixing the coffers 
 
TERMS AND PROCESSES 
 
 151 
 
 and the blocks is the next part of the process. This 
 being done, as already described, taking care to use the 
 centre mark on the coffer as a guide for fixing it fair with 
 the centre lines on the soffit, and using a wood square to 
 prove the square of the style, also using the edge of the 
 square to prove the level of the coffer with the run sides 
 of the soffit, then clean off any excess stuff that may 
 exude at the keyhole and edges of the style. After this 
 the back and front side enrichments are fixed, as already 
 mentioned. Before fixing the paterae a keyed or under- 
 cut hole must be cut in the sunk panels to give a key for 
 the stuff that is used for fixing the paterae. A corre- 
 sponding keyed hole must also be formed on the back 
 of the paterae. This is best done by making the desired 
 size of sinking in the model of the paterae before it is 
 moulded. These sinkings must be undercut after the pa- 
 terae are cast. 
 
 The model of the paterae is generally moulded with a 
 front and back waxed mould. For large paterae, or those 
 having a deep projection a piece of twisted galvanized 
 or copper wire, sufficiently long to enter the keyed holes 
 in the paterae and the soffit, should be inserted in the 
 fixing stuff when fixing the paterae. This method should 
 always be adopted where the bedding surface of the pa- 
 terae is small, so as to enable it to resist the weight of a 
 brush while being painted or gilded. If the paterae are 
 extra deep, and project below the line of the soffit, they 
 should be fixed first, otherwise they are liable to get dis- 
 turbed when fixing the blocks and other enrichments. 
 
 The modillions should be fixed with stiff gauged stuff 
 for the keyed holes in the styles, and the corresponding 
 holes in the blocks (which are made while being cast), 
 and using softer gauged stuff for the bedding surface of 
 the block. After the fixing stuff is laid, place the block 
 
152 CEMENTS AND CONCRETES 
 
 in position, and work it gently but quickly from right to 
 left, so as to force the excess stuff out, and obtain a true 
 and solid bed, taking care that the centre of the block is 
 linable with the centre mark on the soffit, and using a 
 square to prove the squareness of the block, and then 
 clean off the excess stuff. The small enrichments (Figs. 
 6, 7, and 10) are fixed with soft gauged stuff, so that 
 they can be easily and quickly fixed. Small cast work 
 of this kind should always be fixed with soft gauged 
 stuff, as there is very little weight to carry until the stuff is 
 set. The suction alone between the two bodies is often suf- 
 ficient to support the cast until the stuff is set. These small 
 enrichments are moulded with a face or front wax mould. 
 
 where the back section of the leaf is clear or away from 
 the block near the scroll end, as shown in the accom- 
 panying illustration, and seen in fine old buildings, th^ 
 leaf should be cast and fixed separately. An enlarged 
 view of the plan and side elevation of a modillion is 
 shown in illustration No. 5. The bed moulds and the 
 other small enrichments in the entablature are generally 
 cast in wax moulds. 
 
 Modillion. 
 NO. 5. 
 
 Modillions or blocks were 
 formerly cast in three parts, 
 namely, the body, the main part 
 of the leaf, and the tip or curled 
 end of the leaf; the body being 
 cast in a wax piece mould (some- 
 times a plaster piece mould) , and 
 the leaf and its tip in a front and 
 back wax mould, but now the 
 complete block is generally cast 
 in one piece in a gelatine mould. 
 The body of the block may be 
 cast in a gelatine mould, but 
 
TERMS AND PROCESSES 153 
 
 "When fixing the enrichments in an entablature, take 
 special care that they all principle" with each other 
 as already mentioned, thus forming a pleasing and artis- 
 tic finish^ which is characteristic of well-designed mould- 
 ings. 
 
 
 
 : 
 
 \ 
 
 
 u 
 
 M 
 
 
 Fig 2 
 
 
 
 H 
 
 3. -f.- 
 
 \ 
 
 . 1 T 
 
 m 
 
 I 1 ',L 
 
 'Corinthian Cornice. 
 NO. 6. 
 
 To Set Out a Corinthian Cornice, — The members 
 which are enriched in the cornice, shown in the preced- 
 ing plate, are drawn as plain members on this cornice so 
 as to show the profile and method of setting out more 
 clear. 
 
154 CEMENTS AND CONCRETES 
 
 The combined elevation and profile of the cornice 
 shown at Fig. 1, in the accompanying illnstration, No. 6, 
 is an enlarged view of the cornice of the Corinthian en- 
 tablature. The first upright scale contains four parts of 
 the ten into which the .whole entablature is divided, as 
 on the preceding plate. The second scale is divided into 
 five parts, the third of which goes to the modillion, the 
 fourth to the corona, and fifth to the cymatium ; the first 
 and second together are divided into three parts, the first 
 for the reversed cyma at the bottom, the second for the 
 dentils, and the third for the ovolo. The smaller mem- 
 bers are in proportion to the greater, as shown by the 
 smaller divisions on the scale. The modillions are 1-6 
 of the diameter of the column, and their distances two- 
 sixths and a half. Half a diameter is divided on the 
 corona at Fig. 2 into six parts, of which the width of the 
 modillion is two, and the length of it is four. The cap 
 projects 1-3 of those parts, and the distance between the 
 modillions is five. By this rule the exact distance from 
 centre to centre of the modillions is 7-12 of the diameter. 
 The dotted line A C answers to the diminished part of 
 the coJumn, from whence the cornice is projected; the 
 projection being equal to its height, is divided into four 
 parts, as shown by the scale at the bottom of the cor- 
 nice. One-fourth of this scale is divided into six parts, 
 as shown at C, five of which gives the width of the modil- 
 lion. The distance between them is in proportion to it 
 as figured at Fig. 2. The fillets, F F, of the modillion 
 are % of its width, and so is the bead, B. The position 
 and size of the sunk panel are indicated by the dotted 
 lines in the corona at Figs. 1 and 2, the size being ob- 
 tained as shown by the figures in the dotted spaces. The 
 width of the dentils, D, is obtained by dividing the semi- 
 diameter of the column marked on the corona at Fig. 2 
 
TERMS AND PROCESSES 155 
 
 into fourteen parts, two of which gives the width of the 
 dentil, and one the space between them. This space of 
 course is also the width of the in-dentil^ the height of 
 which is one-fourth of the height of the main dentil, as 
 indicated by the small division on the inner side of the 
 second upright scale. 
 
 The centres and radius for describing the profiles of 
 the cymatium or cymarecta, the ovolo, and the inverted 
 cyma or ogee members are indicated by small crosses and 
 dotted lines. 
 
 Mitring. — Mitring is looked upon by the generality of 
 plasterers as a test of speed and ability. As they gener- 
 ally work in pairs on other portions of the work, their in- 
 dividual ability is not easily seen, but when mitring a 
 man carries the operation through alone. Mitring being 
 done by hand, is a near approach to modelling, and is an 
 operation of which a dexterous and good plasterer is nat- 
 urally proud. The quality and time required for mitres 
 greatly depend upon the degree of hardness of the run 
 cornice, also upon the suction. A mitre can be more 
 freely worked and more expeditiously done on a hard 
 cornice surface, and where there is a suction. The extra 
 absorbing powers of brick walls as compared to lath par- 
 titions cause the gauged stuff to get firm sooner, and 
 enables the mouldings to be more readily blocked out be- 
 fore the stuff is set. A common error when mitring is 
 gauging the stuff stronger than that which has been used 
 for the running of the cornice, causing extra swelling 
 and difficulty of ruling the members over, and cutting 
 the run part of the cornice with the joint rule, especially 
 if the stuff sets before the plasterer has had time to rule 
 all the members over, and then being stronger, and con- 
 sequently setting quicker, he has not so much time for 
 forming the members. Ordinary sized mitres can be 
 
156 CEMENTS AND CONCRETES 
 
 done with one gauge by using less plaster than in the 
 gauge for running the cornice, and stiffening the greater 
 portion with dry plaster, and using this for roughing out 
 the mitre; then using the soft portion left for brushing 
 over the members and filling up all holes, and afterwards 
 working the joint rule over the metal to take the su- 
 perfluous stuff off. Should the mitre not be fine enough, 
 the gauged stuff can be further softened on the hawk by 
 adding water, and working it with the gauging trowel, 
 brushing the soft or creamy stuff all over the mitre 
 again, then working the joint rule again. Small mem- 
 bers, and those at the top and bottom of the cornice, 
 where there is most absorption, should be worked by the 
 joint rule first, leaving the large members, drips or coves, 
 or where there is a large body of stuff, to be ruled over 
 last. The joint rule should always be worked horizon- 
 tally, especially when dealing with beads and carvettos. 
 Drips and large members should be worked with the 
 joint rule with an upright motion, because if worked 
 down, the stuff may be pulled down. Mitres should not 
 be worked, fined, or tooled with small tools, as they can 
 and should be brought to a good and straight surface 
 by the proper use of the joint rule. Small tools should 
 only be used for laying the stuff when required, and 
 cleaning out the intersections of the mitres, quirks, and 
 for stopping. A square-ended small tool may be used 
 for smoothing flat, straight surfaces. Returned mitres 
 and short breaks are ^^run down,'' then cut to the re- 
 quired lengths and planted. They may also be mitred 
 by hand. 
 
 Mitre-Mould, — Various attempts have been made to 
 construct a running mould that would form the mitres 
 simultaneously with the cornice running. Most plasterers 
 will have heard of, and some may have tried to make 
 
TERMS AND PROCESSES 157 
 
 and work a mitre-mould to save hand labor. Those who 
 have tried it will have found the results far from satis- 
 factory. The subjoined illustration. No. 7, shows the 
 method of setting out and constructing a mould intended 
 
 -Mitre-Mould. 
 NO. 7. 
 
 for forming the moulding and mitres in one operation. 
 The mould is made by fixing the metal plate at an angle 
 of 45 degrees on the slipper, or in other words fixmg the 
 iron plate at one angle of a square slipper, which allows 
 the mould to run nearly up to the angle, one face of the 
 slipper being used for one side of the wall, and the other 
 
158 CEMENTS AND CONCRETES 
 
 face at right angles being used for the other side of the 
 wall. Fig. 1 shows the method of setting out the profile 
 of mould. A is a given section of a moulding, and B 
 is the section of the moulding at the mitre. To obtain 
 this, first draw the moulding A full size, and then extend 
 the ceiling line and draw another wall line. Then from 
 the projection of the top member draw an angle line at 
 45 degrees. Carry up the projections of the various 
 members to the angle (or mitre line) and then draw hori- 
 zontal lines from the various members ; also centre lines 
 of large members as from a to 1 (the vertical letters). 
 Take off the lines a to 1 (diagonal letters) on the angle 
 line, and set them on the ruling line from a to 1 (hori- 
 zontal letters), and then laying them down to the hori- 
 zontal lines, the intersections give the profile for the 
 mitre-mould. Fig. 2 shows a side elevation of the mitre- 
 mould, and Fig. 3 shows a front elevation. It will be 
 seen that the mitre-mould is an expensive and unsatis- 
 factory fad. The time expended in setting out the elon- 
 gated members, making an extra mould, and cleaning 
 out the intersection by hand (as the mould does not leave 
 a finished mitre), also making good the parts broken by 
 drawing out the mould from interlocked or undercut 
 members in the moulding, is not repaid. An average 
 plasterer would put in all the mitres of an ordinary 
 sized room while the mould was being made. The mould 
 will only run into every second angle, and must be taken 
 off and reversed to fit the next. It may seem a waste of 
 time and space to describe and then show the utter use- 
 lessness of a mitre-mould, but having met many plas- 
 terers who stated that they had used or had seen a mitre- 
 mould that worked wonders, I am constrained to give a 
 description, not only to save future futile controversy, 
 but to show that in this book the much-debated trade 
 
TERMS AND PROCESSES 
 
 le59 
 
 subject has not been omitted. In concluding this sub- 
 ject, it may be stated that not any one of the mitre-mould 
 plasterers would or could practically explain the modus 
 operandi of this mysterious mould. 
 
 Fixing Enrichments. — Enrichments should be fixed 
 straight, square, plumb, and firm. Cornice enrichments, 
 such as bed moulds, friezes, &c., for which a bed or sink- 
 ing to receive them is formed by the running mould, do 
 not require such strong gauges stuff as soffits, medallions, 
 or other hanging casts. For light enrichments the gauged 
 putty and plaster should never be stronger than that 
 used for the cornice, and clean strong size water should 
 be used. This gives more time for fixing a number of 
 casts, and improves the cementing force. The bed for 
 the cast work should be scratched, dusted, and wetted 
 before the cast work is applied. A small portion of fine 
 plaster (the same as used for casting the enrichments) 
 should be gauged with clean size water, to be used for 
 the joints. The gauged fixing stuff should be spread 
 evenly over the back of the cast and over the scratched 
 bed of the moulding. No more should be laid on than 
 will fully fill up the scratches. Then place a small piece 
 of the white or joint gauge on the point, and press the 
 cast into position by gently but quickly sliding the cast 
 twice or thrice backwards and forwards to expel the ^ir 
 and incorporate the two bodies. It is a mistake to dab 
 a lump of gauged stuff at random on the back of the cast 
 and press it on the bed, as the stuff does not properly 
 enter the scratched part of the bed, and the contained 
 air prevents proper cohesion and solidity. When too 
 thick a coat of stuff is laid on the coat, straight and even 
 fixing is more difficult. The excess stuff oozes out at the 
 sides, and unless time and care be taken in cleaning it 
 off, the moulding, or cast, or both, get damaged. A 
 
160 CEMENTS AND CONCRETES 
 
 small portion may also ooze out in the first method, but 
 it will be so thin that it can be brushed off while soft. 
 When fixing medallion blocks or trusses, a dovetailed 
 hole should be cut in the vertical and horizontal parts of 
 the bed, and similar holes in the blocks (which are made 
 when being cast) are filled in with gauged stuff and 
 applied in position. If the cast should be very heavy, 
 or of Portland cement, it is further secured by inserting 
 a slate or iron dowel while the stuff is soft, allowing a 
 portion of the dowel to project to enter into the body of 
 the cast. Heavy casts should be temporarily supported 
 by wood props until the fixing stuff is set. When fix- 
 ing heavy casts the plain surface of the plaster work 
 should be cut as far as the lath to obtain a better and 
 stronger key. The putty in the fixing stuff should be 
 mixed with long strong hair or tow, as described for rib 
 mouldings or ceilings. Hair or tow may also be used 
 advantageously in fixing Portland or other cement work. 
 Cast work, when extremely heavy, should be further se- 
 cured by means of long screws or bolts, placed so as to 
 pass through the cast work and into the timber, the 
 casts being bedded with gauged haired stuff and tem- 
 porarily propped up. The screws or bolts should be 
 fixed before the stuff is set to a^oid the probable dis- 
 turbance of the gauged bedding. Before fixing any cast 
 work they should be placed in position to prove their 
 correct fitting. Centre, side and end lines should be 
 made on the surface of the bed to give a guide for fix- 
 ing. It may be necessary to fix nails at intervals in the 
 lines to give a further guide. 
 
 Mitring Enrichments. — Before fixing continuous or 
 space cast work, the length and width of the panel or 
 room should be set out to prove that the mitres are equal- 
 sided, balanced and have flowing lines. Nothing lookfii 
 
TERMS AND PROCESSES 
 
 161 
 
 so slovenly or unworkmanlike as a mitre in an ornament 
 cut haphazard, with the leading stem disjointed or 
 springing out of a flower or tendril. If the design is 
 vertical, say a bed mould or frieze with an alternate leaf 
 and husk, what can be more offensive to artistic taste 
 than a part of the leaf on one side and a part of the 
 husk on the other side of the mitre! There is no ex- 
 cuse for this want of taste and wanton treatment. A 
 little time expended in setting out the work will obviate 
 these defects. Where there are no shrinking and stretch- 
 ing casts the mitres can be eased by stretching or shrink- 
 ing the cast work at the joints. Stretching or shrinking 
 are evils, and it depends on the design of the enrich- 
 ments which of the two is the lesser, but in most instances 
 shrinking is the greater evil. Shrinking does not require 
 so much labor to make the joints good. Stretching does 
 not show quite so much, especially if the joint is well 
 modelled and of the same color. It also gives greater 
 scope and freedom. It has already been mentioned that 
 in good shops the breaks or other short lengths are set 
 out in the shop and that there are stretching and shrink- 
 ing casts and mitres modelled and made to facilitate the 
 formation of good mitres. This latter method is cer- 
 tainly the cheapest and most satisfactory in the end. The 
 setting out is best done by cutting a lath as a gauge to 
 the length of the cast and marking the length of each 
 cast temporarily on the bed of the cast work from mitre 
 to mitre. When the mitre has been determined on and 
 the casts set out to come in, the marks are made more 
 distant to give a guide for fixing each separate cast as 
 required. It is better to measure thrice than alter twice. 
 Space ornaments should also be set out accurately, but 
 there is no difficulty in the mitres, as the intervening 
 
162 CEMENTS AND CONCRETES 
 
 space between each cast can be increased or diminished 
 as required. 
 
 When fixing medallion blocks^ dentils or paterae, the 
 mitres should be fixed first and then the spaces and posi- 
 tions set out. Special care must be taken when mitring 
 enrichments with distinctive vertical parts, such as fig- 
 ures, or pendants of flowers, or fruit in friezes, that the 
 cast work is not unequally or irregularly scratched so as 
 to enable them to come to an equally balanced mitre at 
 the angles. Where there are no stretchers the cast work 
 should be cut between the main vertical parts, so that the 
 joint on each side will be equal, or, in other words, that 
 the vertical parts will be equidistant from the main or 
 other parts when fixed. The same remarks apply to 
 shrinking. The mitres of running enrichments, such as 
 soffits, etc., are made up with bands or ribbons, which 
 are cast or worked in situ by hand. The latter way is 
 the quickest and most artistic. Another plan is to fix 
 paterae or drops at the internal and external mitres. 
 The scroll work of the enrichment is then formed to 
 spring from the paterae and finish at the patera at the 
 next mitre. Sometimes the inner member at each side 
 of the soffit is worked across at right angles at each mitre, 
 thus forming a sm.all square sinking or panel, which is 
 then filled in with a patera or drop. 
 
 Bed moulds, such as an egg and dart, have internal and 
 external mitre leaf modelled and cast. This is a neat 
 and quick way of forming mitres. A good cornice, with 
 well-modelled and effective ornament, may be disfigured 
 and spoiled by careless mitring, yet it is as easy (and in 
 many cases more so) to make good and satisfactory 
 work. It is therefore best to set out correctly and make 
 sure of a correct finish before beginning to fix. Illustra- 
 
TERMS AND PROCESSES 163 
 
 tion No. 8 shows the method of mitring various forms 
 of fret enrichments. 
 
 Pugging. — Pugging or deafening is a body of plastic 
 materials laid on boards fixed between the joists of a 
 floor, or lath and plaster partitions. It is intended to 
 prevent sound and smells from passing from one room 
 to another. Pugging is generally performed by laying 
 a thick coat of coarse stuff on a foundation of rough 
 boards on fillets, which are nailed on the sides of the 
 joists. Chopped hay, straw or ferns, mixed with lime, is 
 
 ^Fret Or.n'aments. showing their Mitres. 
 NO. 8. 
 
 sometimes used for the plastic coat. Coarse plaster with 
 and without reeds is also used in some districts. Saw- 
 dust is sometimes substituted for reeds. Pugging may 
 be done by forming a foundation with thick rough lath 
 wood. On this a coat, about ^2 i^ch thick, of coarse stuff 
 is laid, and when dry a layer about 2 inches thick of dry 
 ashes or lime riddlings is deposited on it. The upper sur- 
 face is then sprinkled with water and finished with a coat 
 of coarse stuff. This makes sound-proof work, but in the 
 
164 CEMENTS AND CONCRETES 
 
 event of subsequent damage or alterations the dry ashes 
 run out, causing further dust and damage. In some in- 
 stances the dry ashes are gauged with lime. When laid 
 the upper surface is beaten and smoothed with a shovel. 
 This makes sound-proof and durable work, impervious to 
 vermin. Partitions are deafened by lathing between 
 the studding and then laying on a coat of coarse stuff. 
 When dry the partition is lathed and plastered in the 
 usual way. Pugging slabs of fibrous plaster are now 
 largely employed. They have the advantage of being 
 light and dry and are rapidly fixed. 
 
 Sound Ceilings. — No lath and plaster ceilings can be 
 made sound and free from cracks unless the joists are 
 well seasoned, firmly fixed and sufficiently strong to 
 carry the overhead weight, as well as sustain the weight 
 of the lath and plaster, and resist jarring. Ceiling joists 
 should never be more than 12 inches apart from center 
 to center. Where double lath is used the joists may be 
 14 inches from center to center. Good laths, with break 
 joints every three feet, and well nailed, are also impera- 
 tive. If the above dimensions are exceeded the laths 
 are liable to give or twist on account of the weakness of 
 the laths or the weight of the plaster, or both com- 
 bined. If the joists exceed 2 inches in the width they 
 should be counter-lathed or strapped to ensure a key for 
 the plaster. Where it is impracticable or inconvenient 
 to fix the ceiling joists so close they should be brand- 
 ered. This strengthens and stiffens the joists, also gives 
 a free key for the plaster and forms a sound, level ceil- 
 ing. 
 
 Brandered or strapped ceilings are done by nailing 
 wood straps or fillets across the under sides of the joists. 
 The fillets are from 1^^ to 2 inches square and are fixed 
 from 12 to 14 inches from centre to centre. The sizes 
 
TERMS AND PROCESSES 165 
 
 and distance apart varies according to the thickness of 
 the lath and the class of plaster work. Brandered ceil- 
 ings are largely used in some places and make good 
 sound ceilings. 
 
 Cracked Plaster Work. — Cracks in plaster work are 
 due to various causes. They may act individually or in 
 combination. Cracks are often caused by settlement in 
 the building. These cracks may be easily discerned by 
 their breadth, depth and length. They also arise from 
 the shrinkage of bad or unseasoned timber used in the 
 construction or framing of the building, which may 
 cause displacement in the joists or the laths. Cracks 
 are sometimes caused by the laths being too weak, or by 
 too much plaster being laid on weak laths, or too little 
 plaster laid on strong laths. Other causes are the too 
 sudden drying of the work, strong winds or heat, ihe 
 laying of one coat of mortar on another coat, or on walls 
 that have a strong suction which absorbs the moisture or 
 '4ife" of the coat being laid, when it becomes short, or 
 crumbly, scaly and apt to peel or fall off. In this last 
 case it does not set, but only dries and shrinks, which 
 gives rise to cracks, and eventually falls or crumbles 
 away. The use of bad materials, insufficient use of lime 
 and hair, or scamping of labor is often followed by 
 cracks. Insufficient labor and unskilled workmanship in 
 the application of the materials is a great source of 
 trouble, but it will be understood that the best quality 
 of labor will not make bad materials good and strong; 
 and, on the other hand, the best materials will not com- 
 pensate for bad labor. It is only by judicious selection 
 of materials and their skillful manipulation that a high 
 and enduring class of work can be obtained. 
 
 Repairing Old Plaster. — Repairing is also termed 
 '^patching," ''jobbing" and ''making good." "When 
 
166 CEMENTS AND CONCRETES 
 
 repairing or making additions to old plaster work, care 
 should be observed in cutting the joints so that the key of 
 the existing work is not injured or broken. The joints 
 one way should be cut on the studding or joists and in 
 a line with the laths the other way. A joint at the edge 
 of a lath is stronger than at the center. If the lath work 
 is weak the joints should be cut diagonally. Never use 
 a hammer to cut joints on lath work, for the repeated im- 
 pacts will weaken and crack the old work. If the old 
 plaster is hard, cut the joint with the saw or with a ham- 
 mer and chisel and finish with a strong knife. Avoid 
 acute angles in patches. Square, round or oval patches 
 not only look better but are much stronger than zigzag 
 ones. Having cut the joints neat and square on edge 
 and then repaired the old lath work, brush the joints 
 and the laths with a dry broom and then wet the joints, 
 but only dampen the lath work, as excessive water tends 
 to warp the laths. The joints are sometimes painted to 
 prevent damp from extending to the old work or caus- 
 ing injury to any surface decoration. Gauged coarse 
 stuff is generally used for roughing out and gauged putty 
 for finishing ordinary work. The coarse stuff is gen- 
 erally gauged with coarse plaster. For small patches 
 the whole thickness is generally brought out in one coat, 
 but for large patches it is best to lay a first coat and 
 then scratch it in the usual way. If time permits this 
 should stand for one day, or even two, to allow the lath 
 work to settle. The stronger and stiffer the gauge, the 
 less power the laths will have to warp. The floating coat 
 is gauged moderately stiff with coarse plaster or with 
 fine plaster and coarse in equal proportions. 
 
 When laid, the surface is ruled in with a straight- 
 edge, keeping it within the line of the old work to allow 
 for plaster swelling and a thickness of 1-16 inch for the 
 
TERMS AND PROCESSES 167 
 
 finishing coat. It is often necessary to drag the surface 
 down to allow the finishing coat to be ruled fair and 
 flush with the old work. The surface should be left fair 
 but rough. Gauged work should never be scoured, as it 
 only kills the plaster, and therefore weakens the body of 
 the material. The putty for the final coat should be 
 gauged with fine plaster and a little size water. After 
 being laid the surface is ruled flush with the old work, 
 and when firm it should be smartly trowelled off and 
 finally finished with a semi-wet brush. The joints should 
 be trowelled flush and smooth and the old part brushed 
 to free it from any gauged stuff. All rubbish should be 
 damped as it falls, and removed as soon as possible to 
 prevent further dust and dirt. 
 
 Parian or other white cements are used for best work, 
 or where time is a consideration. All white cements 
 having plaster for their basis are manufactured to be 
 non-efflorescent, non-porous, durable, free from liability 
 to unequal shrinkage (which causes cracks), and free in 
 working. They form admirable materials for repairs or 
 additions. When making good old or broken lime plaster 
 work with any of these cements, the joints and lath nails 
 must be painted with red lead, quick drying paint, or 
 with shellac. Galvanized nails ought to be used for the 
 lath work where these cements are to be used. Small holes 
 and cracks are usually stopped with fine plaster gauged 
 with putty, or better still, putty water. Parian cement is 
 also used for a similar purpose. The holes and cracks 
 should be brushed with Parian solution before the stiff 
 Parian is applied. This solution is simply fine Parian 
 gauged to a thin creamy consistency with water. New or 
 damp lime-plastered walls can be painted or papered 
 much sooner, and with greater safety, if brushed with a 
 thin Parian solution. It is also useful for stopping the 
 
168 CEMENTS AND CONCRETES 
 
 suction on dry floating and fibrous slabs before laying 
 the final coat. Several of the new patent plaster and 
 white cements are well adapted for repairs, or where 
 time is limited. 
 
 Gauged Work. — All gauged work should be regulated 
 in strength according to the purpose required. A brick 
 or stone wall would not require so much plaster as a lath 
 partition. Work not subject to friction or wear does not 
 require so much plaster. If the work is required for 
 immediate use, as with running screeds, or blocking out 
 large mouldings, or fixing large castings much plaster 
 must be used. The amount of plaster required for scaf- 
 fold work varies from ^ to equal proportions for gaug- 
 ing coarse stuff or setting stuff, and from 1-3 to equal 
 proportions for coarse stuff for heavy cornices, and 1-3 
 to equal proportions for putty and fixing ornament. The 
 amount of plaster also depends upon the quality of the 
 plaster, some of which are much stronger than others. 
 Coarse plaster that is of a dark and sandy nature is gen- 
 erally weak, sets quickly, and becomes soft and useless. 
 Fine plaster should be used for gauging putty when run- 
 ning cornices, also for fixing enrichments. All gauged 
 work should be gauged with uniformity, each separate 
 gauge having the same amount of water and plaster as 
 required for the bulk of stuff being gauged. Unequal 
 gauging causes hard and soft places in the work, and 
 when more plaster is used in one gauge than another 
 there is an extra expansion caused by the swelling of 
 the plaster, which makes the work more difficult to do 
 when floating, setting, runn,ing mouldings, or mitring. 
 
 A quart and a pint measure should always be kept on 
 the scaffold for measuring the water used for the vari- 
 ous gauges. The quantity of water will regulate the 
 quantity of plaster for each gauge. A proper plaster 
 
TERMS AND PROCESSES 
 
 169 
 
 box should also be on the scaffold, made to hold a sack of 
 plaster, and having a lid made in two halves hinged from 
 the centre. This prevents the plaster from getting dirty 
 by falling stuff, and from getting damp by absorption 
 from the atmosphere. Where there is a large quantity 
 or continuous gauging, the box should be placed on a 
 stand (this is called a stand-box) to prevent unnecessary 
 exertion and loss of time by stooping for each handful. 
 
 When gauging coarse stuff for large surfaces which 
 require several gauges to complete the work in hand, size 
 w^ater should be used in proper proportions with the neat 
 water used for gauging, so as to allow sufficient time to 
 properly manipulate the material. In the event of 
 gauged stuff setting before the work is laid and ruled off, 
 it is difficult to make the surface strong and fair. This 
 also allows the various gauges to be laid on or against 
 the previous ones while they are in a soft state^ thus 
 forming stronger joints and better cohesion between the 
 various gauges. The use of size water in gauged set- 
 ting stuff and putty enables the work to be freely trow- 
 elled and finished. Gauged stuff should not be hand- 
 floated, as excessive working destroys the setting powers 
 of the plaster. 
 
 Joist Lines on Ceilings. — Common flat ceilings show 
 in time the precise position of the joists above, and in 
 many instances the position and form of the lath work 
 can be easily discerned. Many theories have been ad- 
 vanced as to the cause of these unsightly lines or marks, 
 which are so distressing to the mind and eye. In my 
 opinion they are due in a great measure to insufficient 
 material and inferior work. The plaster which is be- 
 tween or separate from the joists is more pervious to the 
 atmosphere than that which is in more direct contact. 
 The air in passing through leaves behind it particles of 
 
170 CEMENTS AND CONCRETES 
 
 dirt assigned in larger measure to the unattached than 
 to the attached portions. Dust that finds ingress be- 
 tween the joints of flooring boards lies on the unattached 
 portions, consequently the joists show themselves as 
 lighter lines on a more or less dirty background. The 
 same causes apply to the lines on the lath work. An- 
 other cause is that the plaster work is too thin. In many 
 instances the floating is brought up from the lath in one 
 coat.- This is a most pernicious habit, as it is not only 
 the cause of lath lines, but the ceiling invariably cracks, 
 and develops spontaneously original patterns indicative 
 of rivers, which too often lead like Niagara to a catas- 
 trophe in the form of falling plaster. Joists and lath 
 lines on thin ceilings may be partly obviated by laying 
 strong brown paper over the upper side of the lath and 
 plaster and then pasting the edges to the sides of the 
 joists, so as to form a cover to the plaster work. The 
 better and most sanitary way is to lay the work in three 
 coats, allow^ the first coat to dry, consolidate the floating 
 coat by well scouring with a hand float, and render the 
 setting coat hard, non-absorbent, and impervious to the 
 air by thorough scouring, trowelling, and brushing. 
 
 Rough Casting. 
 
 Several years ago I was requested by the Editor of 
 '^Architecture and Building'' of New York to prepare a 
 short treatise on the subject of Rough Casting" for 
 publication in that magazine. The article was pub- 
 lished in almost every architectural journal in the coun- 
 try, and Mr. Kidder embodied it in his excellent work. 
 
 Building Construction and Superintendence, Vol. I." 
 I reproduce it here, as the directions given therein have 
 been found to be of the very best, and most workmen in 
 
TERMS AND PROCESSES 
 
 this line of the trade adopt the methods of manipulation 
 herein described. 
 
 Rough casting, or, as it is sometimes called, slap 
 dashing, both of which are synonymous with the French 
 Jiourdage, rough work, and ravalement, having a similar 
 meaning, is a method of plastering the outside of a build- 
 ing much used in the northern part of -Canada because 
 of its being durable, cheap and well adapted to keep out 
 cold winds during the long winters in that section of 
 the world. The methods of applying rough cast and the 
 mixing thereof' do not materially differ from the meth- 
 ods adopted in Northern Europe or even in the North- 
 western States, but it is these minor differences, says a 
 writer in an exchange, that make the Canadian rough 
 casting superior, so far as durability is concerned, to 
 much that is done in other parts of the world. 
 
 There are frame cottages near the City of Toronto and 
 along the northern shores of Lake Ontario that were 
 plastered and roughcasted exteriorly over 40 years ago, 
 and the mortar today is as good and sound as when 
 first put on, and it looks as though it was good for many 
 years yet if the timbers of the building it preserves re- 
 main good. Rough cast buildings are plentiful in every 
 province in the Dominion from Halifax to Vancouver 
 and from Lake Erie to Hudson Bay, and when well built 
 and the rough cast properly mixed and properly applied 
 the result is always satisfactory. It is quite a common 
 occurrence in Manitoba and the Northwest Territories 
 in the winter to find the mercury frozen, yet this inten- 
 sity of frost does not seem to affect the rough casting in 
 the least, though it will chip bricks, contract and expand 
 timber, and render stone as brittle as glass in many 
 cases, and the effect on iron and steel is such as may 
 
172 CEMENTS AND CONCRETES 
 
 prove dangerous if exposed to sudden and unexpected 
 strain. 
 
 In preparing a frame or log building for rough cast- 
 ing care must be taken in putting down the founda- 
 tion. A good stone or brick foundation is, of course, the 
 best, but where rough casting is intended stone or brick 
 foundations are seldom used because of their cost, and 
 the builder is compelled to- use posts of wood. The 
 posts are generally made of white cedar, which has a 
 lasting quality of 35 or 40 years if sound when used. 
 The posts are put in the ground from 3 to 5 feet, the 
 deeper the better, as they should be deep enough in any 
 case to prevent frost from forcing them upward. When 
 a suflicient number of posts have been properly placed 
 a line is struck on them a proper height from the ground 
 and the tops levelled off. The sills are then placed — all 
 joints being broken on top of posts — and the whole made 
 level. These sills and all the other timber, scantlings 
 and lumber should be well seasoned, if possible, for the 
 greatest enemy to the plasterer is unseasoned timber; 
 shrinkage of joists, posts and scantling not only breaks 
 the bond of the mortar, but causes great cracks in cor- 
 ners and angles that no amount of pointing or patching 
 can ever make good. 
 
 When the frame is up and the rafter on and well se- 
 cured the whole of the outside should be covered with 
 good, sound, common inch stock pine, hemlock, spruce, 
 or other suitable lumber, dressed to a thickness. If put 
 on diagonally so much the better, but this is not abso- 
 lutely necessary if the rough casting is to be of the best 
 quality, as will appear hereafter. 
 
 When it can be done it is best to get all partitions set 
 in place and lathed, the roof on and all necessary out- 
 side finish or grounds put in place and made ready to 
 
TERMS AND PROCESSES 
 
 173 
 
 receive the lath. The carpenter must prepare his finish 
 or grounds for finish to accommodate the extra lath, as 
 the walls will be thickened accordingly. 
 
 For the cheaper sort of rough casting in one or two 
 coats the following method of lathing is employed: Nail 
 laths on the boarding — over paper or felt, if paper or 
 felt is used — perpendicularly 16 inches from centre to 
 centre if 4 foot laths are used, or 18 inches or 1 foot 
 from center to center if 3 foot laths are used. The whole 
 surface to be rough cast will require lathing this way. 
 When done lath as is ordinarily done with No. 1 pine 
 lath, breaking joints every 15 inches. Put 5 nails in 
 each lath, driving each nail home solid, coat over w^ith 
 mortar, well haired, and that has been made four or more 
 days; smooth and straighten as well as possible with a 
 darby. When done and while yet soft tlie rough cast is 
 thrown on it with such force as to drive the pebbles or 
 small stones deep into it. The mixture or dash, as it is 
 called, is composed of fine gravel, clean washed from all 
 earthy particles and mixed with pure lime and water 
 till the whole is of a semi-fluid consistency. This is 
 mixed in a shallow tub or pail and is thrown upon the 
 plastered wall with a wooden float about 5 or 6 inches 
 long and as many wide, made of inch pine, and fitted 
 with a wooden handle. While with this tool the plaster- 
 er throws on the rough cast with his right hand, he holds 
 in his left a common white-wash brush, which he dips 
 into the rough cast and then brushes over the mortar 
 and rough cast, which gives them, when finished, a reg- 
 ular, uniform color and appearance. 
 
 For this sort of work the following proportions will 
 answer : To one barrel of prepared gravel use a quarter 
 of a barrel of putty; mix well before using. This may 
 be colored to suit the taste by using the proper materials, 
 
174 CEMENTS AND CONCRETES 
 
 as given further on. It must be understood that the fore- 
 going is the cheapest sort of rough casting, and is not 
 recommended where more durable but more expensive 
 work is required. 
 
 The best mode of doing this work as practised in the 
 Lake district of Ontario is nearly as follows. Have the 
 frame of building prepared as indicated in the foregoing, 
 with partitions all put in and well braced throughout and 
 well secured. Lath diagonally with No. 1 pine lath, 
 keeping IV2 inches space between the lath. Nail each 
 lath with 5 nails, and break joints every eighteen inches. 
 Over this lath again diagonally in the opposite direction, 
 keeping the same space between the lath and breaking 
 joints as before. Careful and solid nailing is required 
 for this layer of lathing, as the permanency of the work 
 depends to some extent on this portion of it being honest- 
 ly done. The mortar used for the first coat should have 
 a goodly supply of cow's hair mixed in with it, and 
 should be made at least four days before using. The 
 operator must see to it that the mortar be well pressed 
 into the key or interstices of the lathing to make it 
 hold good. The face of the work must be well scratched 
 to form a key for the second coat, which must not be put 
 on before the first or scratch coat is dry. The mortar for 
 the second coat is made in the same way as that re- 
 quired for the first coat, and is applied in a similar man- 
 ner, with the exception that the scratch coat must be 
 well damped before the second coat is put on in order 
 to keep the second coat moist and soft until the dash or 
 rough cast is thrown in. The rough casting is done ex- 
 actly in the same manner as described for the cheaper 
 sort of rough cast work. 
 
 A building finished in this manner, if the work is well 
 done, possesses many advantages over the ordinary 
 
TERMS AND PROCESSES 175 
 
 wood coyered structure. It is much warmer being al- 
 most air tight so far as the walls are concerned. It is 
 safer, as fire will not eat its way through work of that 
 kind for a long time. It is cleaner, as it will not prove 
 such a harbor for insects. It may be made as handsome 
 as desired, for before the rough cast is dashed it may be 
 laid off in panels of any shape by having strips of bat- 
 tens tacked over the soft mortar, which may be removed 
 after the rough casting is done and the coloring finished. 
 It is much superior to the so-called brick veneered house, 
 as it is warmer, more exempt from fire and cheaper. 
 
 For 100 yards of rough casting in the manner 
 described the following quantities will be required: 1800 
 laths, 12 bushels of lime, li/^ barrels of best cow hair, 
 1% yards of sand, % yard of prepared gravel and 16 
 pounds of hot cut lath nails, 1^/4 inches long. The gravel 
 should be sifted through a i/^ inch mesh screen, and 
 should be washed before mixing with the lime putty. 
 
 To color 100 yards in any of the tints named herewith 
 use the following quantities of ingredients : For a blue 
 black mix 5 pounds of lamp black in the dash. For a 
 buff use 5 pounds of green copperas, to which add 1 
 pound of fresh cow manure ; strain all and mix well with 
 the dash. A fine terra cotta is made by using 15 pounds 
 of metallic oxide mixed with 5 pounds of green copperas. 
 A dark green color is made by using 5 pounds of green 
 copperas and 4 pounds of lamp black. Many tints of 
 these colors may be obtained by varying the quantities 
 given. The colors obtained by these methods are perma- 
 nent; they do not fade or change with time or atmos- 
 pheric variations. Many other colors are used but few 
 stand like the ones named. A brick color may be obtained 
 by the use of Venetian red and umber mixed in whisky 
 first and then poured into the dash until the proper tint 
 
176 
 
 CEMENTS AND CONCRETES 
 
 is obtained. In time, however, like all earthy pig- 
 ments, these colors fade and have a sickly appearance; 
 they answer better in cements than when incorporated 
 with fat limes. 
 
VARIOUS METHODS OF RUNNING CORNICES, 
 CIRCLES, ELLIPSES AND OTHER ORNAMEN- 
 TAL STUCCO WORK. 
 
 Diminished Columns. — The diminishing of columns is 
 an interesting but somewhat difficult operation. Great 
 care must be exercised not to overdo the entasis or swell- 
 ing. The swell may commence very gradually from the 
 base to the capital, or the third part of the column may 
 be of the same diameter, and then swell and diminish for 
 the remainder of its height. Two methods are here given 
 to show how this may be done. These are given more 
 to illustrate the method of setting out the diminished 
 floating rulesi — so necessary to the plasterer — than to 
 define the iswell or diminishing of a column, which, being 
 within limits a matter of taste, pertains more correctly 
 to the architect. 
 
 The best instrument for forming a diminished column 
 (plain or fluted) is a diminished floating rule, with a 
 cutting edge made to the contour of the proposed col- 
 umn. This rule is used to determine the central posi- 
 tion of the astragal and base mouldings (which act as 
 bearings when ruling off the floating stuff' and the final 
 coat), so as to obtain a true and uniform diminish, and 
 also to form a fair surface. The appended illustration 
 No. 9 elucidates the method of setting out diminished 
 columns which is also used for setting out the diminished 
 rule for both columns. The method for setting out a 
 diminished rule for a column that diminishes two thirds 
 of its height is as follows : The dimensions of the column 
 
 177 
 
METHODS OF WORK 
 
 179 
 
 having been fixed, i. e., the height of the shaft and itiS 
 upper and lower diameters, draw a perpendicular line 
 which may be taken as the centre line of the column; 
 then set out the upper and lower diameters, as shown in 
 Fig. la. This figure also shows one-half of the eon- 
 structural brick work, and the plaster, which is dis- 
 tinguished by being dark shaded with the floating rule 
 in position. A floating rule for forming the curved and 
 diminished surface requires an iron plate, similar to a 
 mould plate, as shown, so that it will cut the stuff off 
 cleaner and truer, and last longer. The other half of the 
 elevation shows the lines and divisions for obtaining and 
 setting out the entasis. 
 
 To diminish the column, first divide the height into 
 three equal parts then at the lower third (5) draw a 
 semicircle equal to the lower diameter of the column. 
 Next divide the upper portion of the column into four 
 equal parts, as -shown at 1, 2, 3 and 4, then draw a line, 
 parallel with the axis or centre line of the column, from 
 figure 1 at the top of the column, cutting the semicircle 
 at 1, divide the remainder of the semicircle into four 
 equal parts, w^hich gives the diminishing points. From 
 these points draw lines parallel to the axis of the column, 
 and from the corresponding figures, or from 2 to 2, and 
 so on. In these intersecting points fix pins or nails, and 
 bend a flexible strip of wood or metal round the nails, 
 and draw the curved line. The whole line from top to 
 bottom is then, transferred on to the board that is to be 
 used for making the floating rule. This column will have 
 its greatest diameter for one-third of its height, and the 
 upper portion its entasis. This method is so far defect- 
 ive as to require the curve to be drawn by hand, a de- 
 fect, however, obviated by using a column trammel, 
 which is used for a column that diminishes with a grace- 
 
180 CEMENTS AND CONCRETES 
 
 ful curve from the base to top of the shaft. This tramme] 
 is made as follows: 
 
 Column Trammel. — A column trammel is simple in 
 construction, and when carefully used gives very satis- 
 factory results^ forming a graceful diminished curve 
 from the lower diameter to the upper diameter of the 
 shaft. Before describing the method of setting out and 
 constructing the column trammel, the method of finding 
 the point D on Fig. 2 is given on a separate sketch (Pig. 
 5) to show the method more clearly. 
 
 Fig. 5 illustrates the method of obtaining the point D, 
 on which the centre pin is fixed for the trammel to 
 slide on while working. This point also gives the length 
 of the radius-rod. This sketch is reduced one-half in 
 size to that of Fig. 2a, but the letters correspond to it. 
 Having set out the axis or centre line of the column (A 
 B) and the base line (AC) (extending the latter indefi- 
 nitely) as described for Fig. la, proceed as follows. From 
 A as a centre, and from A to B as a radius, describe an 
 arc, as indicated by the dotted line; then from the in- 
 tersecting point at C as a centre^ and from C to the 
 point at B as a radius (as indicated by the dotted line), 
 describe an arc until it cuts the base line at K. This 
 done add the distance from the point at A to the point 
 at K to the base line, outward from the point at C, which 
 gives the desired point D. 
 
 The trammel should be set out on a wall or a clean 
 floor. To set it out, first draw a line to the exact height 
 of the proposed column, as A B on Fig. 2a, then draw 
 a line (indefinitely in length) at right angles to A B, as 
 shown from A to D. This line A B is the axis or centre 
 line of the column, and the line A D is the base line. To 
 construct the trammel, take two rules, each the length of 
 the column,, and about 2 inches wide, and 1^/2 ii^- thick ; 
 
METHODS OF WORK 181 
 
 fix one on each side of the axis of the column, taking care 
 to keep them equidistant and parallel to the axis, and 
 forming a grooved space about 2 inches wide, as shown 
 at a, a, the rules, and b the groove. These rules are 
 made thicker than the board intended for the floating 
 rule, so as to allow the trammel pencil to run freely 
 when marking the diminished line on the board. This 
 is shown by the section at Fig. 1. This is as when done 
 in a temporary way on a floor, but a better way is to 
 fix the rules on a board (a flooring board will be found 
 suitable). This makes a permanent groove, and forms an 
 easy ground for the sliding block to work smoothly. It 
 also allows a greater space for a thicker board for the 
 floating rule. 
 
 Fig. 2 shows enlarged details of the groove rules (A, 
 A,) the groove (b,) the sliding block (B), with the pin 
 (H), the radius-rod (F), with the pencil (G), and the 
 board for the floating rule (C), with the diminished 
 line. Fig. 1 shows a section of Fig. 2. The letters in 
 all figures correspond with each other. Fig. 2a shows 
 the whole column with the trammel and finished floating 
 rule (C). Make the radius-rod about 2 inches wide, 1 
 inch thick and in length a little longer than the distance 
 from D to B, and the half diameter of base of the shaft. 
 The sliding block (H) is about 4 inches long and equal 
 in depth and width to that of the sliding groove (b). It 
 should be made smooth, and fit the groove easily, so that 
 it will slide freely from end to end when working. In 
 the exact centre of the block fix a hardwood pin or a 
 round nail (H). This must be fixed exactly over the 
 axis of the column, and so fitted that it will run imme- 
 diately over it from end to end. Bore a hole in the ra- 
 dius-rod to fit this pin, then from the centre of the pin 
 set off exactly half the diameter of the base of the col- 
 
182 CEMENTS AND CONCRETES 
 
 umn on the radius-rod, which will give the point for 
 the pencil hole (G). At this point bore a hole large 
 enough to receive a pencil, which must be tightly held in 
 it. At the lower end of the radius-rod cut a slot just 
 wide enough to receive the center pin at D. 
 
 A plan of the radius-rod with the slot and centre pin 
 is ishown at Fig. 3 and a section at Fig. 4. The block 
 beneath the radius-rod, in the section is used to keep the 
 rod level with the rules and sliding block, as shown on 
 Fig. 1. To ascertain the length to cut the slot, place the 
 radius-rod along the line A D, and the pencil at the out- 
 side of the semi-diameter at the base of the column, and 
 slide it to its place; mark on the rod where the centre 
 pin (D) comes; then place the pencil end of the rod at 
 the top diameter, and mark the rod again at the centre 
 pin; this will give the length of the pin. Having made 
 the trammel, provide a stout board to form the floating 
 rule (cc). This board should be planed on both sides 
 and one edge. Place it near the rules a a, keeping the 
 planed edge outwards, and parallel with the axis or 
 centre line of the column. This allows the planed edge 
 of the floating rule to be used as a straight edge to 
 plumb by when fixing the top and bottom rims or mould- 
 ings, w^hich are used as guides and bearings when float- 
 ing the column. Place the sliding block in position, and 
 lay the radius-rod over the center pin, and the pin of the 
 sliding block, keeping the rod in a line with D A, tak- 
 ing care that the pencil is in its true position ; then care- 
 fully move it upwards, and pressing the pencil gently 
 upon the board which will give the line for cutting the 
 diminishing floating rule. The floating edge is strength- 
 ened by nailing a strip of sheet iron on the board in a 
 similar w^ay to that in which a mould plate on a running 
 mould is treated. This is of special use when floating 
 
METHODS OF WORK 
 
 m 
 
 diminished fluted columns or pilasters, as the thin and 
 sharp edge allows the flutes to be more easily formed. 
 The diminished line on the metal plate can also be 
 formed with the trammel. 
 
 A column trammel can also be used for setting out 
 other diminished floating rules for columns less in size 
 than the original one. The only alteration required for 
 this purpose is to alter the point D to -suit the size of the 
 proposed column, and the shortening of the radius-rod. 
 It will be seen that the floating rules for both columns 
 are made long enough to bear on the base and necking 
 mouldings, but it is usual to make them shorter bo as to 
 bear on cast or run rims or collars, which are fixed at 
 the top and bottom of the shaft. 
 
 Constructing Plain Diminished Columns. — Plain 
 diminished columns and pilasters are formed with a 
 diminished rule fashioned at both ends to work on the 
 necking and base mouldings (termed rims), or on collars. 
 The method of making rims and collars, which are used 
 as bearings, is as described for diminished fluted 
 columns. 
 
 To Set out the Flutes of Diminished Column, — The 
 annexed illustration No. 10 elucidates the method of set- 
 ting out the flutes of a column. Fig. 1 shows the half 
 plan of a column ; A is the plan of the flutes a'u the base, 
 and B the plan at the top of the shaft. Fig. 2 shows the 
 elevation of the column, with the various parts marked. 
 Fig. 3 shov\^s the plan and centres for setting out the 
 flutings for the different orders with arrises or with fil- 
 lets. A fluted column may be divided into twenty, 
 twenty-four, or twenty-six flutes, according to the style 
 or order. There are two different sorts of flutes used. 
 One is worked to an arris, and sunk down in different 
 depths, one of which is described by the fourth part of 
 
CEMENTS AND CONCRETES 
 
 P U AIM 
 
 —DiiMiNisHED Fluted Columns. 
 
 NO. 10. 
 
METHODS OF WORK 
 
 185 
 
 the circle, one by the sixth, and others by the half 
 circle, as shown at C, D, E, Fig. 3. 
 
 The square or fillet of the second kind is equal to one- 
 third part of the flute. It will be seen in Fig. 2 that 
 two lines are shown at the top of the flutes. The lower 
 one shows how the flutes finish, when the fourth and 
 sixth depths are taken, and the top line when the half- 
 circle is taken together with the fillets. Flutes that 
 finish with an arris are usually employed for columns in 
 the Doric order, and those that finish with fillets are used 
 in the other orders. The fillets or lists at the top and 
 bottom of the shaft of a column, which serve to divide 
 the shaft from the capital and base mouldings, are com- 
 monly called the upper and lower fillets, and sometimes 
 the horizontal fillets, but in architecture they are known 
 as ^'cinctures." The curved parts at the top and bottom 
 of the shaft which are iisually curved into the upper and 
 lower fillets by a concave curve or inverted cavetto, are 
 in architecture termed ' ' apophygis. ' ' 
 
 Constructing Diminished Fluted Columns. — The 
 formation of diminished fluted columns by means of a 
 running mould is an absorbing and vexed topic among 
 plasterers, and many ingenious plans have been advanced 
 for the construction of hinged and spring running 
 moulds, and diminished running rules. I have known 
 more than one self-improving plasterer who has ex- 
 pended a vast deal of time and lime (not forgetting 
 plaster) to prove by actual practice the possibility of 
 running a diminished fluted column, while others have 
 been content to work them by theory, forgetting that an 
 ounce of practice is worth a ton of theory. Some men 
 thought they had accomplished a feat when they had 
 run a single flute with a hinged mould, between two run- 
 ning rules fixed to form diminution in width, forget 
 
186 CEMENTS AND CONCRETES 
 
 ting or not knowing that flutes diminish in depth as well 
 as width. 
 
 The difference in depth of flutes, at the base and the 
 top of the shaft, is shown at A, the base, and B, the top, 
 in Fig. 1, illustration No. 10. Running moulds have also 
 been made with springs to regulate the diminish in 
 depth, but their action was uncertain, and they are also 
 too expensive for the purpose. Another form of run- 
 ning mould was made by fixing wire, catgut, or leather 
 on one end of one of the slippers, and on the upper edge 
 of the stock, so that the slipper, when being forced up 
 the diminished space between the running rules, became 
 more angular, or in other words, the slipper on which 
 one end of the wire was attached was higher up the 
 diminished space than the other slipper, and thus caused 
 the stock to cant forward, or be drawn out of an up- 
 right, and reduce the depth of the flute. The stock in 
 this case is connected to the slippers not by hinges, but 
 by a pivot inserted at each slipper to allow the stock 
 to cant forward when pulled by the wire. This form 
 of mould also proved to be too erratic in its working 
 to be of useful service. Running moulds having the 
 stock connected to a slipper at each side by means of 
 two hinges (termed a double-hinged mould) allow the 
 mould to assume an angular or slanting form as it passes 
 up the diminished space, thus forming a diminution in 
 the width of flute, but it does not form it with a true 
 arc all the way. On the contrary, it assumes an elliptical 
 form which becomes more and more pronounced as it 
 reaches the top of the shaft. 
 
 The nearest approach to perfection in running dimin- 
 ished flute is performed by means of a running mould 
 made with hinged slippers as described, but having the 
 mould plate and stock cut through the centre of the 
 
METHODS OF WORK 
 
 187 
 
 profile, the two parts being then connected by a hinge. 
 This form of running mould (termed a ^'triple-hinged 
 mould '0 allows the mould to collapse in the form of a 
 V on plan, and the slippers to run level or parallel with 
 each other, thus forming each half of the flute alike, and 
 at right angles from the centre. Still this has the defect 
 of forming the flute without the necessary decrease in 
 depth. 
 
 A method for diminishing the depth of the flutes is to 
 make the running rules with a diminish on face, or 
 rather to make them with an increasing thickness towards 
 the top ends, so that the mould when running up on the 
 increasing thickness will form a corresponding de- 
 creased depth of flute. When running a fluted column 
 by this process, the running rules are fixed flush with 
 the face line of the fillets. Only one flute can be run at 
 a time, but twelve may be in band at the same time. As 
 there are generally twenty-four flutes in a column, 
 twelve rules would be required to keep a couple of 
 plasterers going. When the fi,^st set of flutes are run, 
 the rules are taken off and fixed to run the remaining 
 flutes. When all are run, the returned ends at top and 
 bottom require to be made good. It will be seen that the 
 running rules for this method must be carefully made 
 and fixed to ensure true lines and forms. It will be 
 understood that a bed or ground must first be formed 
 as a guide for setting out and fixing the running rules 
 on. This is done with the aid of a diminished floating 
 rule. It will also be self-evident ^hat the floating rule 
 would be more profitably employed for forming the 
 entire shaft with the flutes, thus dispensing with run- 
 ning rules and hinged moulds. This method of running 
 the flutes is slo^^' and tedious^ but tne worst part is that 
 the flutes are not true segments ; in fact, the whole of the 
 
188 CEMENTS AND CONCRETES 
 
 methods mentioned are more or less a rule of thumb, un- 
 certain and inaccurate. 
 
 A knowledge of the rudiments of geometry will prove 
 that the true form of a diminished and swelled fluted 
 column cannot be run with a mould, however ingeniously 
 made. This may be proved by cutting a plaster or card- 
 board disc to the former radius of a single flute, and de- 
 scribing a line round it on a board. This would be the 
 form the mould, when at right angles at the bottom of 
 the shaft, would give the flute. Then place the disc in 
 an oblique position (the same as the hinged mould would 
 be at the top), and project the plans by means of a set 
 square on to the board. It will be seen that the mould 
 would give the flute an elliptical form. It may be 
 further explained by stating that when the mould is 
 square at the base, or at right angles with the vertical 
 running rules, the form of the flute would be a true 
 segment; but when the mould is moved up the dimin- 
 ished space between the rules, it assumes an oblique or 
 slanting position. It gives the flute an elliptical form, 
 which increases and becomes more pronounced as it ap- 
 proaches the necking. It may be said that the pointed 
 or elliptical defects can be filled in and worked fair 
 with circular hand floats, but this plan necessitates a 
 series of hand floats to fit the ever-varying widths and 
 depths of the flutes. 
 
 It may seem unnecessary to describe the above meth- 
 ods, and then to point out their defects. However, the 
 methods and defects are given to prevent the rising plas- 
 terer falling into the same errors, and to enable him to 
 resist and rebut the arguments that are so often ad- 
 vanced by some men, who persistently assert that their 
 own particular way (genera-lly one of the methods al- 
 
METHODS OF WORK 189 
 
 ready mentioned) is the correct and only way of proper- 
 ly performing this different bnt interesting operation. 
 
 It is worthy of note, to show the interest taken in 
 this subject that a patent was obtained for a running 
 mould and process for forming diminished fluted col- 
 umns, in 1878, which obtained a provisional protection 
 for ^'improvements in moulds or templates for running 
 stucco or ceinent tapered fluted columns.'' The follow- 
 ing is a copy of the specification in extenso: — 
 
 This invention relates to the running of stucco or ce- 
 ment in forming fluted or other columns, pillars, or pi- 
 lasters, and similar surfaces^ in a more simple, economi- 
 cal, and expeditious manner than heretofore; and the 
 nature and novelty of the invention as applied for run- 
 ning or making the body part of a fluted tapered col- 
 umn of stucco or cement, consisting in constructing a 
 short box-shaped template, having two sides joined to- 
 gether by a back plate outside, with a handle upon it, 
 for drawing it up and down the column, and with an 
 open space inside the back between the sides open above 
 and below, equal to any desired section or segment of 
 the column at its base or widest part, into which the 
 column is equally divided by narrow longitudinal 
 strips of wood, against which the inner edge and end 
 surfaces of the sides of the template slide close, so as to 
 prevent the escape of the semi-liquid or stucco. A thin 
 elastic segmental mould plate is hinged or jointed at its 
 ends to the inner faces or edges of the template, formed 
 in its inner scraping edge to correspond to the segmental 
 curve of the base of the column, with rounded pro- 
 jections corresponding to the flutes to be formed on the 
 column. This plate and its hinges are laid at an angle 
 highest at the inner scraping edge, and inclined down- 
 wards towards the back, leaving a space between it and 
 
190 CEMENTS AND CONCRETES 
 
 the back for the free passage or escape of the super- 
 fluous stucco or cement scraped off the column during 
 the ascent of the mould along the column on its longi- 
 tudinal shaping strips before mentioned. 
 
 ^ ^ The one end or side of the mould is made to slide or 
 contract laterally in slots or other equivalent guides in 
 the back of the mould frame as it ascends along the con- 
 tracting or tapering longitudinal laths, the thin plate 
 bending or yielding down in a curvilinear form on its 
 end hinges before mentioned, so as to bulge inwards while 
 bending downwards^ and so contract the column in a 
 nearly true radical and segmental form from the bottom 
 to the top of the column, the angle at which the scrap- 
 ing mould plate is set on its hinges determining this con- 
 traction of the scraping centre edge of its segment radi- 
 cally in a ratio corresponding to the contraction of the 
 lengths of the segment and moving sides of the mould, 
 which, for large moulds and columns, might be car- 
 ried and drawn up by handles secured to the tops of 
 the ends of the moulds with ropes led up and over pul- 
 leys at the top of the column, thence down to the hand 
 of the operators, so that the mould may be raised and 
 lowered at pleasure to form the whole segment of the 
 column from the bottom to the top in nearly as simple 
 and efficient a manner as plain mouldings are at present 
 run by the usual simple edge scraping moulds, one seg- 
 . ment being run after the other in succession until the 
 column is finished. 
 
 ' ' For plain or other forms of columns the inner scrap- 
 ing edge of the mould plate is made to correspond to the 
 tapered surface of the column to be formed plain, seg- 
 mental, or fluted as desired ; and for flat, square, or polyg- 
 onal columns, which do not require a segmental mould 
 scraper, this would be made straight, either plaia or 
 
METHODS OF WORK 
 
 191 
 
 iluted, as desired on its scraping edge, and set horizontal- 
 ly on its hinges, instead of at an angle as described for 
 the segmental mould scraper for forming round col- 
 umns ; and this mould scraping plate in any case is pre- 
 ferred to be made of thin elastic steel or tempered cop- 
 per or brass, which would bend and contract the flutes or 
 ridges on the surface of the columns or pillars, equally 
 and proportionally to the several parts of the column 
 over which the mould is traversed. Although the mould 
 or template has been described as made with only one 
 of its ends movable laterally, it is to be understood that 
 both ends or sides may be fitted so as to move in a 
 similar manner to suit different kinds of work. 
 
 This patent method would be better understood if it 
 had been illustrated. No provision for diminishing the 
 depth of the flutes is given in this method. The use of 
 flexible metal for diminishing purposes cannot be relied 
 on for accurate work. 
 
 Another method for forming diminished fluted col- 
 umns is thus performed : — Make a single flute in plaster, 
 and use it as a mould for casting reverse flutes composed 
 of fibrous plaster. After casting as many reverse flutes 
 as there are flutes in the proposed column, indurate them 
 with litharge oil or paraffin wax. Casts of the necking 
 and base, each with about 3 inches of the fluted shaft, are 
 fixed on the brick core. The shaft is then laid with 
 Portland cement (or other desired cement) and sand un- 
 til within about one-third of the line of fillets, and 
 while this stuff is still soft, take a reverse flute 
 (previously oiled) and press it into position, using the 
 cement flutes at the necking and base as guides for fix- 
 ing, and using a diminished floating rule to prove the 
 outline. Repeat this process until all the flutes in the 
 column are filled with reverse flutes. The intervening 
 
192 CEMENTS AND CONCRETES 
 
 spaces or fillets are then filled in with gauged cement 
 until flush with the outer surface of the reverse flutes, 
 and further regulated with the floating rule. When the 
 stuff is set, the reverse flutes are extracted, and any de- 
 fects in the flutes made good. On the care in fixing the 
 reverse flutes and filling in the fillets depends the success 
 of this method. 
 
 Diminished fluted columns are also made by casting 
 two vertical halves, and then fixing them on the brick 
 core. The halves are fixed by means of cement dots, 
 which are laid on the core at intervals. (Corresponding 
 dots are laid on the interior of the casts. The casts 
 are then pressed on the core until the dots meet, and 
 both halves are in proper position. The cast work is 
 made solid with the core by pouring a thin and weak 
 solution of cement and sand into an orifice at the neck- 
 ing. 
 
 The cement and sand should be mixed in the propor- 
 tion of one of the former to five of the latter. This 
 gauge has sufficient binding power and strength for this 
 purpose, and is not liable to expand or contract in wet or 
 dry weather. This process is useful for small work, and 
 makes a good job when cleanly cast and neatly fixed. The 
 necking with the capital and the base may be fixed be- 
 fore or after the shaft casts are fixed, according to cir- 
 cumstances. The shaft casts are best formed in a reverse 
 casting mould. 
 
 Another method of casting a diminished fluted col- 
 umn is effected by making a reverse casting mould. Fix 
 it round the core, and pour the gauged material in at 
 the top of the necking mould. By using a reverse 
 casting mould made with a plaster face and a wood back- 
 ing, or a mould made in fibrous plaster, the whole 
 column with the core can be made in one piece. Hoi- 
 
METHODS OF WORK 
 
 193 
 
 low columns, compoised of Portland .cement concrete, 
 can be made to carry any weight supported by a stone 
 column, or one constructed with a brick core of equal 
 diameter. Cast hollow columns are made by temporarily 
 fixing a wood or fibrous plaster core tapered to one end 
 to allow it to be withdrawn when the concrete is set. A 
 rough wooden or a fibrous plaster hollow core is used 
 when casting a hollow column in situ. The core in this 
 case is left in. 
 
 After many years' experience and observation on this 
 subject, I am of opinion that the true form of a dimin- 
 ished fluted column (composed in Portland or similar 
 cement, and constructed in situ) is best obtained by 
 hand, with the aid of cement rims or plaster collars 
 and a diminished floating rule. Most plasterers will 
 admit that what can be and is done in stone or wood, 
 can be done equally well in cement or planter. A plaster- 
 er has one advantage, inasmuch as he can add as well 
 as subtract when forming circular surfaces, whereas the 
 mason can only subtract. The two methods hereafter 
 given for forming diminished fluted columns by hand 
 are simple, speedy, and accurate. They are on one prin- 
 cipal, and each may be used as circumstances require: 
 one is termed the ^^rim method," and the other the 
 ' ' collar method. ' ' 
 
 Forming Diminished Fluted Column ty the Bim 
 Method. — First make models of the half circumferences 
 of the astragal or necking and base mouldings, each 
 having about 4 inches of the fluted shaft, as shown at 
 Fig. 1, the plan and Fig. 2, the elevation, on illustra- 
 tion No. 10. To make the models, cut a mould plate to 
 fit each of the full-sized mouldings, and the required 
 size of the shaft, and horse'' them with radius-rods, 
 and run a little over one-half of each circumference in 
 
194 CEMENTS AND CONCRETES 
 
 plaster, and then cut them to the exact half circumfer- 
 ence. This done, set out the flutes, then cut them out 
 and form the returned ends. The method of setting out 
 the flutes on the ends of the models is shown on the plan 
 at Fig. 1. A is the plan at the base, and B the plan at 
 the top of the shaft. The returned ends of flutes are 
 shown on the elevation, Fig. 2. Add the square plinth 
 to the base, as shown on the plan at Fig. 1, which com- 
 pletes the models. Piece mould the models in plaster, 
 and then cast as many half astragal and bases as re- 
 quired. The materials used for the casts must be of the 
 same kind as intended for the shaft. The brick or core 
 of the column is now cleaned and well wetted, and then 
 the astragal and bases are fixed in position, using the 
 diminished floating rule to prove if they are central, and 
 the fillets linable with each other. Apply a plumb rule 
 on the back edge of the floating rule to test if the astragal 
 and base are concentrical and parallel with each other. 
 When these half casts are fixed together on the shaft they 
 are termed ^'rims. " The intermediate space on the 
 shaft is then filled in and ruled off with the diminished 
 floating rule, using the rims as bearings and guides for 
 forming the fillet line of shaft. 
 
 The methods of forming a diminished fluted column 
 by the ^^rim method'' is further elucidated by the an- 
 nexed illustration. No. 11. This shows an elevation of 
 the brick core of a shaft with the astragal rim, A and 
 the base rim, B, fixed in position. D is the diminished 
 floating rule in position for floating the main or fillet line 
 of the shaft. The method of using a diminished flute 
 rule for the flutes is illustrated in the ' ' collar method. ' ' 
 
 A second diminished floating rule is required to form 
 the back surface of the flutes. This can be quickly made 
 by laying the first rule flat on the floor, and from this^ 
 
METHODS OF WORK 195 
 
 with compasses, describe the back line of the flute on 
 another board, which is afterwards cut to the desired 
 
 -Floated Fluted Columns, Kim Method. 
 NO. n. 
 
 line. This rule is used as a. long joint rule to form the 
 flutes. The rule should be worked with uniform pres- 
 sure, the man at the top working in unison with the man 
 
196 CEMENTS AND CONCRETESi 
 
 at the bottom, both working the rule with a circular 
 cutting motion. The flutes are fined down by the aid of 
 a small float semicircular in section. For extra large 
 columns three floats should be used — No. 1 cut to the 
 top section, No. 2 cut to the middle section, and No. 3 
 cut to the bottom section. The length of the floats may 
 vary from 5 inches to 7 inches, according to the height of 
 the column. If the columns are required with a smooth 
 surface, the flutes are worked as above, but the floats are 
 covered with fine felt, leather, or rubber, and the sur- 
 face finished smooth with short joint rules or with pieces 
 of flexible busks. The cast parts of the shaft, to the 
 fillet members of the astragal and the base, should be 
 keyed with a drag, so that the whole shaft, from arris to 
 arris of the astragal and base fillets^ can be fined, thus 
 giving a uniform texture and color, and avoiding a sur- 
 face joint of the cast work and the fined work. 
 
 A modification of this method is as follows: — The 
 lower horizontal jfiUet of the shaft and the base mouldings 
 are caist separately, the fillet part being used as bear- 
 ings for floating the shaft, as already described, and the 
 base is fixed after the shaft is fined. This plan is useful 
 for some purposes, such as for extra large columns, as it 
 gives more freedom for working the shafts and the bases 
 are not so liable to get injured while working over them. 
 
 Running Diminished Fluted Column iy the Collar 
 Method, — Run a plaster collar about IV2 inches wide to 
 the diameter of the top horizontal fillet of the shaft. 
 The thickness must be regulated according to the space 
 between the brick core and the line of fillet. Cut this 
 collar in halves and fix them on the brick core, keeping 
 the under side in a line and level with the top of the 
 proposed fillet of the shaft. Run another collar to fit 
 the horizontal fillet at the base of the 3haft, and fix the 
 
METHODS OF WORK 
 
 197 
 
 upper side of this one level w^ith the bottom edge of the 
 fillet at base of the shaft. This done, make two plaster 
 models of the flutes, one for the top and one for the 
 bottom of the shaft, each about 3 inches wide, and in 
 thickness according to the brick core, the diameter being 
 taken about 1 inch above the returned ends of the flutes 
 at the top and bottom of the shaft. These models are 
 set out and made as described for the first method, but 
 using plaster instead of cement for the casts. The plaster 
 casts are fixed in position, and then the brick core is 
 laid and ruled off, using the main diminished floating 
 rule (and the plain collars as bearings) for forming the 
 main contour or line of the vertical fillets, including the 
 horizontal or top and bottom fillets of the shaft, and 
 using the diminished flute floating rule (and the plaster 
 models of the flutes as bearings) for forming the flut3s. 
 This done, the fluted collars are cut out, the spaces filled 
 in and ruled off, and the returned ends of the flutes 
 are formed, and then the whole shaft is fined while the 
 work is green. The fillet collars are then cut out, and 
 the astragal and base mouldings are then fixed, thus 
 completing the column. It will be seen that this method 
 entirely dispenses with joints between cast and floated 
 work on the shaft, and allows it to be fined in one opera- 
 tion. 
 
 The method of running diminished fluted columns 
 with the aid of collars is further elucidated by the an- 
 nexed illustration No. 12. A C is the top fillet collar, B C 
 the bottom fillet collar, and F C and F C are the top and 
 bottom flute collars fixed on the brick core of the column. 
 D R is the main diminished floating rule in position for 
 forming the main contour or fillet line of the column. 
 This rule is rebated at the top to allow for a bearing on 
 the top as well as on the edge of the collar. This rule 
 
198 CEMENTS AND CONCRETES 
 
 also forms the profile of the top and bottom horizontal 
 fillets, and the curved parts of the shafts below the top 
 fillet and above the bottom fillet. F R is the flute 
 
 Forming Fluted Columns — Collar MeIhod. 
 
 NO. 12. 
 
 floating rule in position when forming the flutes. The 
 ends of this rule as shown bear on the back surface of 
 a flute as indicated by the dotted lines. A portion of the 
 astragal moulding, A, with a part of the shaft is shown 
 
METHODS OF WORK 
 
 199 
 
 so as to indicate the position to fix the fillet collar^ A C ; 
 a portion of the base moulding;, B with a part of the 
 shaft, is also given to show the position of the bottom 
 fillet collar, B. C. It will be seen that these collars form 
 fair bed for the astragal and base mouldings, and when 
 taken off they leave true joints as indicated by the ar- 
 rows at A and B. 
 
 A modification of the above methods for forming the 
 fillets and flutes is effected as follows: — Fill in the spaces 
 on the shaft between the collars in this method — or the 
 rims in the former method — and rule them off with a 
 main diminished floating rule as already described and 
 when the stuff is firm but not set, the positions and forms 
 of the fillets and flutes are set out on the floated surface, 
 then the flutes are cut out by hand by means of gouges 
 and drags, and afterwards fined as already described. 
 This system is specially useful for small columns. 
 
 For extra high columns it will be found difficult to 
 work a floating rule to form the whole height of the 
 column in one operation, in fact, for some columns to be 
 seen in cities, which are 20 feet to 30 feet high, and 
 even higher, it would be impossible to form them with 
 one floating rule. It is therefore noiEessary to divide the 
 column into two or more sections^ and cut the floating 
 rules accordingly. In this case two or more plaster col- 
 lars about 3 inches wide, and made to the exact circum- 
 ference of the column at the point of division, are re- 
 quired. These collars are then temporarily fixed in posi- 
 tion to act as screeds, and after the whole surface of the 
 column is filled in and ruled off, the collars are cut out 
 and the spaces filled in, and then the whole surface 
 fined in one operation. Three or even more floats, as 
 already described, are required for the fining of high or 
 massive columns. 
 
200 CEMENTS AND CONCEETES 
 
 Having now briefly reviewed the more or less useful 
 methods, and described some of the most useful and 
 practical methods, the conclusion to be drawn is, that 
 diminished fluted columns are best done by working 
 them b}^ hand, with the aid of diminished floating rules 
 and cast or run bearings. This first or rim method will 
 be found useful for many purposes; but the collar'meth- 
 od, with the addition of intermediate collars for extra 
 high columns, is the best for general use. 
 
 Diminished Fluted Pilasters. — Pilasters are said to be 
 a Roman invention. They bear an analogy to columns 
 in their parts, have the same names and standard of 
 measurements, and are diminished and fluted on the same 
 principals. When pilasters are placed behind columns, 
 and very near them, they should, not project above one- 
 eighth of their diameter; but if they are from 6 to 10 
 feet behind the column, as in large porticoes and per- 
 istyles, they should project at least one-sixth of their 
 diameter. When they are in a line with columns, their 
 projection should be regulated by that of the columns. 
 When pilasters are used alone as principals in composi- 
 tion, they should be made to project one-fourth of their 
 diameter to give regularity to the returned parts of the 
 capitals. The process for forming pilasters is the same 
 as for columns. 
 
 Panelled Coves. — Large coves, segmental or elliptical 
 on section, having their surfaces panelled with mouldings 
 which spring from the back or above a wall or main 
 cornice, and finish at or intersect with a beam or other 
 moulding at the top or crown of the cove, require to be 
 carefully set out and screeded. The floating is done 
 from two horizontal screed* made at the top and bottom 
 of the cove, and from these vertical screeds are formed, 
 and then the intermediate spaces or bays are filled in 
 
METHODS OF WORK 
 
 201 
 
 and ruled off with a floating rule bearing on the vertical 
 screeds. The horizontal screeds are easily made, but the 
 vertical ones require special care to insure all being uni- 
 form in section. These screeds are formed with a tem- 
 plate cut to the desired section, and about 2 inches thick. 
 For large coves they are made with three or more pieces 
 of wood. The most correct and expeditious way of 
 forming circular screeds is by the ''pressed screed" 
 process. 
 
 Section of Cove Showing Pressed Screed Process. 
 NO. 13. 
 
 Pressed screeds are simple and expeditious in con- 
 struction. They form accurate grounds for floating pur- 
 poses and for running mouldings on circular surfaces. 
 The method of forming pressed screeds and floating co^^es 
 is shown in the accompanying illustration No. 13. This 
 shows the section of a cove with the main or wall cornice 
 and the crown moulding. F is a nib rule used when 
 
202 CEMENTS AND CONCRETES 
 
 running the main cornice. To float this cove for the run- 
 ning of vertical mouldings, first form the top and bottom 
 horizontal screeds (A and B)^ then form the pressed 
 screed. This is effected by temporarily fixing the . 
 template, G, or by one man holding it on the bottom 
 screed, and another man holding it on the top screed, 
 while a third spreads and presses the gauged coarse stuff 
 until the space between the first coating and edge of the 
 template is filled up, then drawing the trowel down each 
 side of the template clears off any superfluous stuff. 
 
 -Fig. I, Floating Coves. Yic. 2, Levelling Rule. 
 NO. 14. 
 
 The template, which has been previously oiled, is then 
 removed, leaving a narrow, but true and smooth screed 
 ready for working on. This method gives a truer 
 screed, especially in elliptical or long circular screeds, 
 - than floating or working with a template, because if the 
 template is not worked perfectly vei1;ical, the curve of 
 the screed is altered and not true. 
 
 The subjoined illustration (No. 14) elucidates the 
 method of forming the screeds for floating cove surfaces, 
 also for floating segmental, elliptical, or any other form 
 
METHODS OF WORK 
 
 203 
 
 of interior and exterior angles in coves. Fig. 1 shows a 
 plan of the cove. The letters in this sketch correspond 
 with those on the same parts in the section on illustration 
 No. 13. The first coating and the various bays, after 
 the screeds are made^ are indicated by crossed diagonal 
 lines at the D's. The top screed, A, should be levelled 
 from end to end and made parallel in depth with the 
 crown moulding. Their levelness is tested with the aid 
 of a ^ levelling'' rule. The bottom screed, B, should 
 be made parallel with the main cornice, so that the pro- 
 jection of the vertical mouldings will be uniform. The 
 vertical screeds, C, are next formed, making the first two 
 near the internal angles, then two at the external angles. 
 The intervening space is now^ set out, so that the screeds 
 may be 8 to 10 feet apart. The screeds may be formed 
 farther apart according to requirements. If there are 
 vertical mouldings to be run in the cove, the screeds 
 should be made at the sides of the proposed mouldings. 
 It is always best to have two or three screeds near the 
 angles, so as to give a bearing for the floating rule, R. 
 This shows the position of the rule w^hen floating the in- 
 ternal angle. The external angles on the other side are 
 formed in the same way. The distance between the 
 screeds used for floating the angles can be regulated ac- 
 cording to the depth or form of the angle. It will be 
 understood that the floating rule must be sufficiently 
 long to bear on two vertical screeds, and reach to the 
 extreme point of the angle. The floating rule, R, here 
 shown is termed a grooved floating rule. This is grooved 
 on both sides, as shown by the section, S. 
 
 Fig. 2 shows the elevation of a levelling rule as used 
 for levelling dots for ceiling, beam, or crown screeds. 
 This is similar to an ordinary parallel rule, but with the 
 addition of a fillet, F, nailed flush with the bottom edge 
 
204 CEMENTS AND CONCRETES 
 
 to form a ledge to carry the spirit level, L. The level- 
 ling rule is applied on the dots to test if they are level ; 
 this is proved by inspecting the spirit-level ; if one dot is 
 too full it must be depressed until the levelling rule is 
 level. 
 
 Diminished Mouldings. — Mouldings that diminish in 
 depth or projection as well as in width (termed double 
 diminished mouldings'') are not so common as those that 
 diminish in width only. The diminish in width is simple, 
 and is obtained by the aid of a ''triple-slippered" run- 
 ning mould and two running rules fixed to form a 
 diminished space, as described h-ereafter. The formation 
 of a regular and pleasing diminish in depth greatly de- 
 pends on the profile of the moulding. A moulding hav- 
 ing small members, especially at the sides, is more diffi- 
 cult to diminish than one having large members, es- 
 pecially one with plain and deep fillets at the sides. 
 Three methods are here given for running double dimin- 
 ished mouldings on domes, cupolas, or vaulted ceilings, 
 or on lower surfaces. These methods give good results, 
 especially if a little thought for the requirements of the 
 case is bestowed on the designing of the moulding. 
 
 Double Diminished Mouldings, False Screed Method,-- 
 By this method the diminish in depth is obtained by false 
 screeds, and the diminish in width by the aid of a dimin- 
 ished rule, which is fixed on the centre of the profile or 
 bed of enrichment. This method is elucidated in the fol- 
 lowing illustrations. The annexed illustration No. 15, 
 shows the section of a vertical moulding on the plaster 
 or floated surface of the inside of a dome, C is the 
 main cornice from, which the inner line of the dome 
 springs. The D's are dots which are used to regulate 
 the -diminish of the false screeds. The various thickness- 
 es and positions of the dots are obtained by setting out 
 
METHODS OF WORK 
 
 205 
 
 the full size of the section on a floor or worked out to a 
 scale. If the section is elliptical, dots should be placed 
 at the points where the transition of curves takes place. 
 When the surface of the dome has been floated^ the 
 diminishing dots, D, are placed at each side of the in- 
 tended moulding: and at their prbper positions, begin- 
 
 •Section ^Double Diminished Mouldings— 
 False Screed Method. 
 
 NO. 15. 
 
 ning above the main cornice, C, and going upwards m 
 rotation but having no dot at the top. The spaces be- 
 tween the dots are next filled and ruled in, bearing on 
 the various dots with the curved rules or templates. 
 When ruling the top bay of the screed, the top end of 
 the rule bears on the original floating at the top or ex- 
 
METHODS OF WORK 
 
 207 
 
 treme point, this point being the true thickness of the 
 screed. 
 
 Illustration No. 16 shows the plan and elevation of the 
 work. Fig. 1 shows it in progress, and Fig. 2 when 
 finished. The A's on plan and elevation (Fig. 1) are 
 false screeds, the B's are brackets, while C C indicates 
 the diminished running rule. This rule is made as fol- 
 low^s: — First plane one face of a pine board about % 
 inch thick, and of sufficient length and w^idth for the 
 desired purpose. On this make a centre line from end 
 to end. From this centre line set off the width at one 
 end, and the diminished width at the other end ; then 
 extend the diminished width lines from end to end, and 
 then plane the running edges to the diminished lines. In 
 order to allow the rule to bend freely to the curved 
 surface, make a series of saw-cuts crossways on the back 
 or bed face. The false screeds are made as already de- 
 scribed. A centre screed for the running rule is made 
 by the aid of a template. This is made with two slippers, 
 one on each side, similar to a running mould, so as to run 
 on the false screeds, the centre or cutting edge of the 
 template being made to the depth of the proposed screed. 
 The face surface of the bracket is then laid with gauged 
 stuff and finished off by working the template up and 
 down. This done, fix the diminished rule, C, on the 
 centre of the screed. The running mould, E, on the 
 plan is made with the slippers, one to bear on the centre 
 screed and against the running rule, and the other to 
 bear on the side false screed. The slippers are made 
 circular on their running edges, so as to fit the circular 
 screeds. A short slipper at the nib gives more freedom 
 and ease when running the moulding, and the mould is 
 not so liable to cut up the screeds. After the moulding 
 is run on both sides, take the running rule off, then cut 
 
208 CEMENTS AND CONCRETES 
 
 the false screeds down to the floating;, and make the sides 
 of the fillet good, and then fix the enrichment. Fig. 2 
 shows the plan and elevation of the finished moulding; 
 and enrichment. A, on the plan, shows one side of the 
 moulding before the false screed is cut off, and G show^s 
 the screed cut off and the member made good to the 
 floating. The amount of diminish from the bottom to 
 the top of the moulding is shown at the brackets B and 
 B, and by the profiles of the cornice on the plan and ele- 
 vation. The bed and section of the enrichment is shown 
 at F on the plan. As tliis enrichment is diminished (in 
 width and projection) the whole length must be 
 modelled. 
 
 Running Double Diminished Mouldings^ Diminished 
 Ride Method.i — This is a method which is introduced, 
 and is somewhat similar to the first method described. It 
 is well adapted for running mouldings, having no en- 
 richment on the centre of the section, the bed of which 
 may be used as a screed and bed for a running rule, as 
 used for the first method. By this method the whole 
 moulding is run in one operation. The diminish in 
 depth is obtained by the use of two running rules 
 diminished on the face, or in other words., diminished 
 in thicknesSi. The diminish in the thickness of the 
 rules is obtained by setting the full size, as described for 
 the false screeds in the first method. A series of saw- 
 cuts must be made on the backs of the rules to allow them 
 to bend to the circular surface of the dome. These 
 rules act in a similar way to the false screed used in the 
 first method, with the addition that they form the fillets 
 of the outside members, thus avoiding cutting the screeds 
 down and making good the fillets. They are also used for 
 obtaining the diminish in width. This is effected by 
 first making a central line on the bed surface of the 
 
METHODS OF WORK 
 
 209 
 
 proposed moulding ; then from this line, at each side, set 
 out the half width of the moulding, including the bear- 
 ing parts of the running mould. This is done at the 
 widest or bottom end of the moulding, and at the nar- 
 rowest or top end. Then from these width marks, lines 
 are extended from end to end. On these lines, nails are 
 inserted from 2 to 3 feet apart, which act as guides for 
 fixing the running rules. The inner sides of the rule are 
 placed against the outer sides of the nails and fixed, and 
 then the guide nails are extracted, thus forming the 
 diminished space and bearings. A triple-hinged mould 
 with a slipper at each side is used, so that it will close up 
 while being run up the diminished space. The stock is 
 rebated, so that it will run on the tops and inner sides 
 of the rules. The mould plate must be cut to fit the 
 section at the greatest width of the moulding, but care 
 must be taken that the depth at the outer members is 
 the same as proposed for the top. The ends of the inner 
 slippers and the adjoining parts of the stock are cut 
 so as to leave an open space, to allow both parts to work 
 freely when the mould assumes a raking position, as 
 shown on illustratiort No. 17. 
 
 The extra depth of the square of the outside members 
 is formed by the running rules. It may here be re- 
 marked that the thickness of the rules at the top should 
 be made about % i^ich thicker than the depth of the 
 square part of the outside members. For example, if 
 the depth of the fillets or square part of the outside 
 members is 1 inch, the rules should be II/2 inches thick 
 at the top. This allows for the requisite bearing for the 
 running mould. The ends of the stock that bear on the 
 inside of the rules must be rounded off to allow the 
 mould to run freely when it closes up while being run 
 up between the dimipished space. 
 
210 CEMENTS AND CONCRETES 
 
 The various parts of the running mould are shown in 
 the annexed illustration No. 17. Fig. 1 shows the mould 
 
 Diminished Rule Method. 
 
 NO. 17. 
 
 in position at the bottom or widest part of the moulding ; 
 R, are sections of the running rulesj. S, S, the slip- 
 
METHODS OF WORK 
 
 211 
 
 pers; and H, the hinges which connect the two 
 halves of the stock to the slippers. The hinge which 
 connects the mould in the centre is fixed on the other 
 side of the stock. Its position is indicated by dotted 
 lines. Fig. 2 shows the form of the mould when at the 
 top of the moulding. The letters correspond with those 
 on Fig. 1. The thin seams at the centre and sides of the 
 moulding which are caused by the joint of the mould in 
 the centre and by the joint of the mould and the rules 
 are cleaned off by hand. This method, like the first, has 
 the defect that the actual diminish or the whole depth of 
 diminish lies in the fillets of the outside members of the 
 . moulding. The difference between the diminished mem- 
 beris and the regular members will be most noticeable on 
 the adjoining members, the vertical fillets of the cavettos. 
 If this defect should prove offensive to the eye, it may to 
 some extent be remedied by working these members down 
 by hand, with the aid of planes, gouges, drags, and joint 
 rules, after the moulding is run, so as to reduce the depth 
 of the fillets, and throw the difference into the cavettos. 
 A line should be set out to the desired diminish on the 
 . fillets to act as guides when working the cavettos down. 
 Running Double Diminished Mouldings^ Top Rule 
 Method. — Kunning double diminished mouldings by the 
 aid of a ' ^ top rule ' ' is another method that I have intro- 
 duced for this purpose. The diminish in width is ob- 
 tained by fixing two slipper running rules to the de- 
 sired diminish and a triple-hinged mould ais previously 
 described, and as shown at Figs. 1 and 2 on the an- 
 nexed illustration. No. 18. Fig. 1 shows the running 
 mould, M, and the slipper rules, R, R, at the full-sized 
 or springing end of the moulding, and Fig. 2 shows the 
 running mould and rules at the diminished end. The 
 dimiiaishing depth is obtained by the aid of a ''top rule'' 
 
212 CEMENTS AND CONCRETES 
 
 which is fixed on two blocks, one at each end of the 
 moulding, as shown at Fig. 3. This shows the elevation 
 
 Elevations, Plan, and Sections of 
 •Running Mould and Rules for Diminished 
 Mouldings— Top-Rule Method. 
 
 NO. 18. 
 
 of one side of the running moulds at the springing and 
 diminished ends of the moulding, also the running rules. 
 
METHODS OF WORK 
 
 213 
 
 B is the section of the fixing block at the springing end 
 of the moulding, and D is the fixing block at the dimin- 
 ished end, upon which the top rule, T, is fixed. This 
 rule is fixed on the slant, to suit the desired diminish. 
 It must be made sufficiently wide to allow a bearing for 
 a part of each half of the stock, M, M, of the running 
 mould, and also fixed over the joints of the mould, as 
 shown at T, Figs. 1, 2, and 3. The top rule being fixed 
 on the slant, causes the running mould to gradually cant 
 over when it is drawn from its upright position at the 
 springing end of the moulding to the diminished end, 
 as shown at Fig. 3, thus forming the diminish in the 
 depth of the moulding. M a shows the end section of 
 the stock in an upright position when at the springing 
 end, and M is the section of th.e stock in a slanting posi- 
 tion when at the diminished ends of the moulding. The 
 dotted lines in both indicate the parts of the stocks in- 
 side the slippers, and the angular dotted line at H, H, 
 indicates the splayed or cut side of the hinge. S S is 
 the outer elevation of one slipper when at each end of 
 the moulding, and R is the slipper running rule. It 
 yvill be seen that the running mould at Fig. 1 is some- 
 what similar to the triple-hinged running moulds pre- 
 viously described. But there are two important excep- 
 tions, namely, the hinges at the centre and the two sides 
 of the mould. 
 
 The side hinges for this mould must be cut on one side 
 and the angles rounded off, leaving only one screw-hole, 
 so as to cause less friction, and allow this part of the 
 hinge to turn on a screw when fixed on the slipper. The 
 use of this will be seen hereafter. An elevation of a 
 hinge, before and after it is cut, is shown at Fig. 4. The 
 lower hole on the cut half of the hinge is used, because 
 the nearer the ^ burning points" or pivots are to the 
 
214 CEMENTS AND CONCRETES 
 
 running ground or screed, as the case may be, the less 
 will the bearing edges of the running mould rise when 
 the mould cants over. For instance, if the ^'turning 
 points'' were made at the centre of the 'depth of the 
 mould, the bearing edge of the mould would rise from 
 the ground in proportion to the cant of the stock. This 
 would increase the depth of the lower members (those 
 below the pivots or turning points), instead of dimin- 
 ishing them. This hole must be enlarged so as to admit 
 of a short thick screw to give the necessary strength. It 
 will be understood that this part of the hinge works on 
 the plain part at the head of the screw. 
 
 Having cut the right and left hinges, they are screwed 
 on to the stock and the slippers of the running mould, 
 keeping the half of the hinge with the three screw-holes 
 on the stock, and the cut part with one screw-hole on 
 the slippers, as shown at H, H, Fig. 1. It will also be 
 noticed that these hinges are fixed at the lower edge of 
 the mould. This is done so as to allow the stock of the 
 mould to cant from its basie for the reason already men- 
 tioned. When screwing the cut side of the plate to the 
 slipper, allow just sufficient play for the hinge to turn 
 smoothly but firmly on the screw. The centre hinge con- 
 necting the halves of the stock, M, M, is formed with two 
 pieces of metal plate. The inner ends are rounded off 
 to allow them to turn and a circular orifice one-third the 
 wddth of the plate is drilled at the circular ends, and 
 then three or more screw-holes for fixing purposes are 
 drilled on the other ends. The two plates are fastened 
 together with a flat metal ring or with stout copper wire. 
 The thickness of this ring is regulated according to the 
 size of the orifice, but allowing just sufficient play for 
 the plates to turn both ways when the mould assumes a 
 slanting and an angular position, as shown at Fig. 2. 
 
METHODS OF WORK 
 
 215 
 
 An enlarged view of the centre hinge is shown at Fig. 5. 
 The centre hinge is screwed on the inner side or profile 
 of the stock, as shown at C, Fig. 1. An enlarged view 
 of part of the stock at the joint, when inverted for fix- 
 ing the centre hinge, is shown at Fig. 6. The top and 
 bottom edges- and the ends of the stock must be rounded 
 off, to allow it to cant over easily. The diminish of this 
 moulding, both in depth and width, as shown in the illus- 
 tration, is a little more than may generally occur in prac- 
 tice, but this is given to show the various parts more 
 clearly, also what to avoid in the amount of diminish 
 when using this method. 
 
 The diminishing depth here shown is about two-fifths, 
 and the diminishing width about one-third. The dimin- 
 ishing depth, by this method, should not be overdone, 
 because the running mould assumes an angular position 
 both on plan and section, therefore it forms the vertical 
 parts of the members in a slanting line and the horizon- 
 tal parts out of a level. These defects become more pro- 
 nounced at the diminished end of the moulding, as 
 shown at Fig. 2. The top member can easily be made 
 level and fair by hand, but it would entail too much 
 labor to rectify the defects of the other members, there- 
 fore this method should only be used for smal] mould- 
 ings or where the diminish in depth is of a slight nature. 
 The seam at the top member, caused by the joint of the 
 mould, is cleaned off and made good by hand. 
 
 Cupola Panels and Mouldings. — In order to facilitate 
 the setting out and formation of cupola panels and 
 mouldings, the method of drawing them is given. This 
 will be found very useful in the general setting out and 
 construction of cupolas, whether in ''solid" or in 
 ''fibrous plaster.'' Various parts of cupolas and soffits 
 of arches (from designs by J. Gibbs, architect, a pupil 
 
216 CEMENTS AND CONCRETES 
 
 of Wren, and a great patron of the plasterer's art), with 
 the method of drawing same, are illustrated on plate 11. 
 To draw an octagonal cupola, as shown by the plan at 
 Fig. 1, take A B (the width of one side of the octagon) 
 as the base line. From the centre of this erect the per- 
 pendicular line D C, then draw the lines C A and C B ; 
 this will give the triangle ABC, forming the plan of 
 an eighth part of the cupola. The profile (Fig. 2) is 
 made by the quadrant of circle (ABC) directly over 
 the plan. Divide half the base line, A B on plan, into 
 seven parts, as here figured, and six of them will make 
 two panels ; the seventh will remain for the border. The 
 same divisions must be marked on the profile over the 
 line A B, as follows: — Take for the border at the bot- 
 tom four parts, as shown in the plan ; place them on the 
 profile from the base line to No. 1, and draw a line par- 
 allel to the base line of the plan; measure the length of 
 the two central lines marked 2 2, and place it in the 
 profile for the second panel. From thence draw another 
 parallel line, and measure the length of the two central 
 lines at 3 3 in the plan to find the square height of the 
 third panel, and so on to No. 8, as shown in the plan 
 and profile. 
 
 The elevation or upright side of this octagonal cupola 
 (Fig. 3) is made by the following geometrical rule. 
 First draw the base line (A B) on plan even with the 
 base line (A B) of the profile; on this erect the perpen- 
 dicular line (DC) for the centre of the side; then draw 
 all the parallel lines as shown by G G, etc. Take half 
 the length of each line, figured in the plan, and mark it 
 on each side of the middle line of Fig. 3 until the length 
 of every panel is fixed. From these lines and points the 
 forms or outlines of the panels are taken. The inner 
 divisions are brought over to the number of panels con- 
 
7^ 
 
METHODS OF WORK 
 
 217 
 
 tained therein in the same manner as they appear in 
 Fig. 3. The same rule is used for setting the side shown 
 at Fig. 4. 
 
 With regards to the soffits of arches, if they are 
 divided into panels, they must be of any uneven number, 
 as shown at K and L, by having a panel in the centre. 
 The border must not be more than one-sixth nor less 
 than one-seventh part of the whole breadth. The quad- 
 rant or profile, E F (Fig. 2), on which the panels of this 
 semi-circular soffit are divided, will be sufficient to ex- 
 plain them. A circular soffit of lesser breadth is shown 
 at M, and one of greater breadth is shown at N. Sec- 
 tions of each soffit are shown at the top of the eleva- 
 tions. 
 
 The method of constructing the plaster work of cupo- 
 las depends to some extent on the design and size of the 
 panels and mouldings. For example, if the diagonal 
 panels shown in Fig. 3 were sufficiently large to admit 
 of a running mould to run a piece of moulding (on each 
 side of the panels) not less in length than the mitres at 
 each end, the best method would be to run the four sides 
 of all the panels; but if the panels were too small to 
 allow a running mould to run the requisite amount of 
 moulding, it would be necessary to run a part, and cast, 
 or run down, and plant the other parts. In some designs 
 it would be necessary to plant all the mouldings. In 
 some cases the panel mouldings, from the base up to a 
 third or fourth of the height of the cupola, can be con- 
 veniently run; but the panels above this which become 
 smaller, and are too small to admit of their being run 
 with economy, should be planted. Another method is 
 to run all the diagonal mouldings that spring from left 
 to right, as from A to a, in one length from border to 
 
218 CEMENTS AND CONCRETES 
 
 border, and then run the intermediate parts of the 
 mouldings springing from right to left. 
 
 The intermediate parts may also be run down, or cast, 
 and then planted. By this method the intermediate 
 parts only require mitring, and if they are planted the 
 intersections only require to be stopped. If these parts 
 are run, the brackets from right to left must be cut 
 down at the intersections to allow the running mould to 
 pass when running the mouldings from left to right in 
 one length. Whichever method is employed, the surface 
 must be floated true to the various curves to form a 
 ground for the mouldings, whether run or slanted. The 
 surface should also be floated sufficiently smooth to act 
 as screeds without using gauged putty screeds for each 
 moulding. This is done as described for panelled ceil- 
 ings. The groundwork of the floating is effected by first 
 forming a screed on the base border (A B), and one on 
 the top border (at C), and then from these screeds as 
 bearings, form two screeds on the side or vertical bor- 
 ders, thus completing the main screeds, and from which 
 the panel surface is floated. Owing to the brackets and 
 the form of the panels, it is a somewhat difficult opera- 
 tion to float all the panel surfaces with a uniform depth 
 and curve. It will be seen that a floating rule (cut or 
 so constructed to clear the brackets), whether worked 
 vertically or horizontally, cannot travel into the angles, 
 and float the whole surface. This difficulty is overcome 
 by making dots in each angle, or making narrow screeds 
 from angle to angle of each panel. The horizontal dots 
 or screeds, as the case may be, are ruled off with a gauge 
 rule, which is cut to the required depth, and to bear on 
 the side screeds. The vertical screeds are ruled off with 
 the circular rule, on which pieces of board cut to the 
 desired depth and length of the various panels have been 
 
METHODS OF WORK 
 
 219 
 
 previously fixed. The intervening spaces are then ruled 
 off with short rules cut to the angular curves. 
 
 Another and better way is to cut an angular floating 
 rule to fit the curve from A to a, and float all the panel 
 surfaces in a line from border to border in one opera- 
 tion. This angular rule is set out in a similar way as 
 described for angle brackets. The rules for this or the 
 first method must be made to suit the longest line or 
 set of panels. After each set of corresponding panels 
 in the other sides of the cupola is floated, they must be 
 shortened to fit the next set of panels, and so on, until 
 all the panels are floated. The mouldings being dimin- 
 ished in width, are run from a diminished running rule 
 fixed on a centre screed in the same way as described for 
 diminished dome mouldings. The screed for this method 
 is formed by an angular floating rule cut to the angular 
 curve, as already mentioned. For some designs the 
 moulding may be run with a twin-slippered running 
 mould. This form of mould can also be used for form- 
 ing about one inch of the panel surface. This acts as 
 a ground for floating the panel surfaces. When large 
 paterae are used, the ground panel surface may be cast 
 with them, thus avoiding floating and setting. The oc- 
 tagonal panels shown in Fig. 4 are formed in a similar 
 way to Fig. 1. After the vertical and horizontal mould- 
 ings are run, the diagonal sides of the octagons are 
 planted. Where square panels form the design, the 
 mouldings can be run with a radius-rod running mould 
 from a centre pin and block. The sections of the soffits 
 of the arches are run with a radius-rod running mould, 
 fixed on a radius boards and the cross styles or mould- 
 ings, as shown at K and L, are planted. A small portion 
 of the arch should be run to form a ground on which the 
 
220 CEMENTS AND CONCRETES 
 
 enrichments may be modelled. Fibrous plaster is well 
 adapted for constructing the plaster lining of cupolas. 
 
 Panelled Beams, — When panelled beams have mould- 
 ings on the lower part of their sides or faces, and on the 
 soffit to form a sunk panel, they may be run in two parts. 
 Screeds are formed on the two sides, and one in the 
 centre of the soffit. If the mouldings on the sides have 
 more girth or are larger than the portion on the soffit, 
 they may be run from rules fixed on the side of the beam, 
 with the nib bearing on the style or on the soffits. If 
 the style and mouldings on the soffit are small, the mould 
 is made to run the face, style, and soffit moulding in one. 
 If the styles are broad, the moulding on the sunk part 
 of the soffit is run from a parallel running rule fixed in 
 the centre of the soffit, thus forming a double rule to run 
 each side of the sunk moulding. The latter way is most 
 generally used. The end or other mouldings required 
 for panelling the soffit are run down and planted. 
 
 All beams of any length should always have a camber, 
 not only to allow for any settlement that may take place, 
 but to make it more pleasing to the eye. A beam dead 
 level and straight has the appearance of sagging in the 
 centre. This may be termed an optical illusion. 
 
 Trammels for Elliptical Mouldings, — It may at once 
 be pointed out that an ellipse and an oval are not the 
 same. Both ends of an ellipse are similar, and an oval 
 is egg-shaped, one end having a greater curve than the 
 other, therefore the term oval moulding or panel is 
 scarcely correct when applied to the following illustra- 
 tions. This term, however, is be^st known and generally 
 used by most workmen in the building trades. The term 
 ^'ellipticar' is generally applied by plasterers when re- 
 ferring to mouldings where the whole ellipse is not car- 
 ried round, such as for mouldings or elliptical arches, 
 
METHODS OF WORK 
 
 221 
 
 windows, etc.; and the term ''oval/' where the whole 
 figure is completed, such as panels (elliptical on plan J 
 formed on walls or ceilings. In consideration of the 
 common usage of these terms, they will here be used in 
 describing the setting out or v/orking of same. 
 
 Trammels are often used for tunning oval panel 
 mouldings, and for forming the lines when setting out 
 oval templates. Trammels are made of wood or metal. 
 A simple way to make a tram- 
 mel for small work is to sink 
 two grooves at right angles in 
 a hardwood board (termed the 
 plate), about 7 inches long, 
 5 inches wide, and 1 inch 
 thick. The grooves are about 
 1-2 inch deep and 1-2 inch 
 wide. Two hardwood pins are 
 then made to fit the grooves. 
 They have collars to bear on 
 the surface of the plate. The 
 upper part is made round to 
 fit the centre holes of the rod. 
 The subjoined illustration No. 
 19 shows a template and 
 various sorts of template pins. 
 Fig. 1 is a view of a template, 
 with the two pins, rod, with the 
 running mould attached in 
 
 position, and a part of a moulding. Fig. 2 shows various sec- 
 tions of pins. A is the section of the pin as used in Fig. 1, 
 and C is the plan of the pin at the intersection of the 
 grooves. B is the section of a dovetailed pin used for 
 another form of trammel. The rod is made to any de- 
 sired length, so that it may serve for various sized ovals. 
 
 F14 I. 
 
 ^Trammels. 
 
 NO. 19. 
 
222 CEMENTS AND CONCRETES 
 
 The average size for this kind of trammel is about 1 foot 
 6 inches long, 1 inch wide, and 1-4 inch thick. A series 
 of holes 1-4 inch in diameter (to fit the head of the pin) 
 is made about 1-8 inch apart on the flat side. The first 
 hole is made near one end of the rod, and continued 
 down the centre for about 15 inches^ leaving the blank 
 space for screwing on to the running mould. A pin is 
 now laid into each groove, and the size of the desired 
 oval is obtained by regulating the length of the rod at 
 each diameter by means of the holes. The pin in the 
 short groove is the point from which the length of the 
 oval is taken, and the pin in the long groove for the 
 width. The trammel is fixed on the running board by 
 means of two or more screws, as shown. This size of 
 trammel can only be used for oval mouldings from about 
 10 inches to 36 inches at their longest diameter, there- 
 fore larger sizes are required for larger ovals. 
 
 A trammel for running large ovals (say from 6 to 10 
 feet at the major diameter), if made solid, as shown in 
 Fig. 1, would be too heavy and cumbersome for fixing 
 on ceilings where the mouldings are run in situ. A 
 lighter kind termed a cross" template, is made as fol- 
 lows: — Cut three fiooring boards, one a little less in 
 length than the longest diameter of the proposed oval, 
 and two less than the short diameter. Lay them down 
 on a floor in the form of a cross (similar to the grooves 
 in Fig. 1), and fix and brace them together. Four angu- 
 lar braces will hold them together, and allow the whole 
 to be fixed on the ceiling. On the centre of this ground 
 make two lines at right angles to each other, and from 
 these set out the width of the desired grooves at the ends 
 and intersections, and then fix wood fillets, each about 
 one inch thick and two inches wide, to the marks, thus 
 forming the grooves. In order to prevent the pins drop- 
 
METHODS OF WORK 
 
 223 
 
 ping out of the grooves when the trammel is fixed face 
 downward on the ceiling, the inner sides of the fillets 
 should be splayed so as to receive dovetailed pins, as 
 shown at B, Fig. 2. This may also be effected by fixing 
 running rules on the fillets so as to overlap about 1-4 
 inch, over the groove space, thus forming rebated or 
 square grooves. The pins are made with shoulders to 
 fit the grooves. In both modes a 1-inch pin must be in- 
 serted in the trammel pm to prevent the rod dropping. 
 
 A strong, accurate, and permanent trammel can be 
 constructed entirely with metal. To make this, procure 
 a sufficient length of metal tube, about 1-2 inch in diam- 
 eter, having a slot about 1-8 inch wide, cut longitudi- 
 nally. Cut the tube into four pieces, mitring the inter- 
 sections, and fix and brace them together in the form of 
 a cross, as already mentioned. A pin made to fit the slot, 
 fixed in a ball made to fit the tube, completes one of the 
 sliding pins. The rod may be made of metal or wood, 
 but the latter gives more freedom for changing the size 
 for different sized ovals. 
 
 Various methods are employed for running oval panel 
 mouldings on ceilings. The most useful are by means of 
 trammels, or wood or plaster templates. A trammel is 
 a good instrument for running oval panels where the 
 mouldings are not wide. Wide mouldings (say over 1 
 foot) cannot be run true or uniform in width in one 
 operation with a trammel, because the running mould, 
 which is fixed on the end of the rod of the trammel, 
 assumes a raking position when it is between the right 
 angle points of the major and minor diameters of the 
 oval. This raking position takes place at the four joints 
 or change of curves of the oval, and is more pronounced 
 in extra wide mouldings. This difficulty is overcome by 
 running the mouldings in two parts, using a trammel 
 
224 CEMENTS AND CONCRETES 
 
 mould for running the first or inner part, and a run- 
 ning mould (horsed to run on the run part) for running 
 the second or outer part. This is effected by dividing 
 the section of the moulding into two parts, taking care 
 to make the joint at the side of a fillet or in the center 
 of a flat member at the outer side of the part to be run 
 with the trammel mould, so as to allow for a good bear- 
 ing (wide and strong) for the slipper of the running 
 mould used for running the second part. The running 
 mould for the first part is fixed on the rod of the tram- 
 mel as already mentioned. The running mould for the 
 second part is horsed with a circular slipper cut to fit 
 the curve of the first moulding. If the oval has quick 
 curves, a slipper with two pins will give the best re- 
 sults. 
 
 If there is an enrichment in or near the center of the 
 moulding, run the moulding in three parts, using the 
 bed of the enrichment (which is run with a trammel 
 mould) as a center running rule for running the outer 
 and inner parts, which are run with circular or pin- 
 slippered running moulds, as already described. It will 
 be seen that by using either of these three methods, wide 
 mouldings for oval panels can be run uniform on width ; 
 the trammel mould giving the form of the oval to the 
 fi.rst part of the moulding, or to the center running rule, 
 and the curved slippered running moulds giving the de- 
 sired uniformity of width to the full section of the 
 moulding. Most forms of oval panel mouldings are best 
 run with templates. When run with trammels, or with 
 radius-rods, the running mould is apt to jump and cause 
 cripples at the junction of the major and minor diam- 
 eters. 
 
 Templates for Running Elliptical Mouldings. — The 
 true form of an ellipsis can only be derived from the 
 
METHODS OP WORK 
 
 225 
 
 diagonal cut from the cone or the cylinder, and the near- 
 est approximation to this curve must be obtained by 
 continuous motion. There is no other instrument so 
 well adapted for effecting this purpose as a trammel. 
 For a true ellipsis, make the distance from the outer end 
 of the rod to the nearest point or centre pin equal to 
 
 Template and Pin-Mould for Running 
 Elliptical Arch Mouldings. 
 
 NO. 20. 
 
 half the shortest or minor diameter of the ellipsis, and 
 from the centre pin to the outer pin equal to half the 
 longest or major diameter. This shows the use of a 
 trammel for setting out the lines to make a template for 
 this form of ellipsis. 
 
 The subjoined illustration No. 20 elucidates the method 
 of setting out another form of ellipsis; also an oval hav- 
 
226 CEMENTS AND CONCRETES 
 
 ing its major axis one-third greater than its minor. This 
 also shows the template and a pin running mould in posi- 
 tion for running an elliptical arch moulding. The 
 template (Fig. 1) is made to extend below the springing 
 line of the arch, so as to allow the mould to be run down 
 to the spring of arch and save mitring. The template 
 for running the arch extends to the shaded part; but 
 to utilize the space the curve has been continued round 
 to show a method of setting out a template from which 
 an oval moulding can be run, the oval having its major 
 axis one-third greater than its minor. The method of 
 setting out is as follows: First draw the line AB, the 
 greater diameter, to the desired length; then bisect it, 
 and erect the perpendicular line CD ; this being the 
 lesser diameter, is made a third less than the line AB. 
 Then bisect each half of the line, which will divide the 
 line AB into four equal parts and give the centres E, E, 
 which are the centres for describing the ends, as from 
 F to F, and Fl to F2. Then from the centres C and D 
 describe the flat curves from F to Fl, and from F to F2, 
 which complete the oval. It is, however, better to set 
 out this template by the trammel, as the junction of the 
 segments of the circles always has a more or less crip- 
 pled look. 
 
 Fig. 2 shows a pin-mould" in position when run- 
 ning an elliptical arch moulding. This mould is pro- 
 vided with two hardwood pins inserted into the bearing 
 face of the slipper. The pins bear on the edge of the 
 template, and owing to their position, and being apart, 
 allow the mould to take any change of curve without 
 * ^jumping." 
 
 Before running elliptical mouldings on arches or win- 
 dows, the centres and running rods should be tested, so 
 . that the mouldings will intersect accurately, and so avoid 
 
METHODS OF WORK 
 
 227 
 
 jumps at the change of curves. All centre pins should 
 be level with each other, and equidistant from the centre 
 of the arch or window. The outline and intersections of 
 the proposed moulding can be tested by temporarily fix- 
 ing a pencil on the outer and inner profiles of the run- 
 ning mould, then working the mould over the screeds, 
 so that the pencils will form two lines. I have heard of 
 a three-centered elliptical hood moulding being run over 
 a window with what is called a ' ' bolt radius-rod. ' ' This 
 rod i;s made in two parts and connected with a hinge, 
 and held straight when running the long diameter with 
 a bolt and sockets where fixed at the joint. The run- 
 ning mould is fixed on one end, and a centre plate on 
 the other in the usual way. The long diameter of the 
 moulding is run first, and when the radius-rod reaches 
 the change of curve the bolt is drawn back, and the short 
 diameter of the moulding run with the short part of the 
 radius-rod. A nail is inserted in a board which is pre- 
 viously fixed in the window opening. The nail must be 
 fixed in a line with the change of curve so as to stop 
 the radius-rod, and hold the long part in position while 
 the short part is working. The same operation is re- 
 peated for the other side of the work. It is needless to 
 say that this method is far too' complicated to be serv- 
 iceable for general purposes. 
 
 Templates are used for running most forms of ellip- 
 tical panel mouldings. Plasterers may make their own 
 templates or running rules by using fibrous plaster casts 
 as a substitute for wood. This is effected by first set- 
 ting out a quarter of the proposed oval panel, then cut 
 out or run a temporary plaster running rule to fit the 
 inner line, allowing a space for the slipper of a running 
 mould. Cut a reverse running mould to the section of 
 the proposed fibrous plaster rules (say about 1 inch thick 
 
228 CEMENTS AND CONCRETES 
 
 and 3 inches wide), then run the quarter length of the 
 oval, and after making true joints at the ends, cast four 
 fibrous plaster quarters, and then lay and fix them re- 
 versely, thus completing the full oval template or run- 
 ning rule. The full oval running rule can also be run 
 in situ and in one operation. This may be done with 
 a trammel or with radius-rods, according to the form 
 and size of the panel. Strong and stiff gauged plaster 
 or a strong white cement, should be used for the run- 
 nixig rule, to enable it to resist the friction of the run- 
 ning mould while running the moulding. Radius-rods 
 are more often used for setting out the lines for oval tem- 
 plates than for running the mouldings. Circular mould- 
 ings — vertical, horizontal, or angular — run off circular 
 grounds require special running rules, so that they will 
 take or bend to the double curvature. For this purpose^ 
 cane, flexible metal pipes, and wooden rules, having series 
 of saw-cuts on the backs and sides, have been used, but 
 cast fibrous plaster rules or a jack template are more 
 suitable for most of these purposes. Template can also 
 be made by means of a plasterer's oval. 
 
 Plaster er^s Oval. — The subjoined illustration (No. 21) 
 elucidates the setting out of this form of oval to any 
 given size, also the method of formi,ng two oval mould- 
 ings from two circle mouldings. The ovals are formed 
 by running two circular mouldings in plaster, the diam- 
 eter of one being exactly double that of the other. Each 
 circle is cut into four quadrants or quarters. Two of the 
 quadrants of the larger circle form the sides of one oval, 
 and two quadrants of the smaller circle form the ends, 
 the four segments making a fairly good oval. The re- 
 maining segments constitute another oval of similar size 
 and shape. The method is simple and speedy, and it 
 can also be employed for the formation of elliptical 
 
METHODS OF WOEK 
 
 22S 
 
230 CEMENTS AND CONCRETES 
 
 mouldings on arches, doors, or windows as well as for 
 oval panel mouldings. The formation of ovals by this 
 method has been employed by plasterers for genera- 
 tions, but owing to the want of a definite rule for set- 
 ting out this form of oval to any given size, its use has 
 been somewhat limited. To meet this want, I have in- 
 vented a method which can be adopted for most pur- 
 poses, and which I give h^re for the first time. For 
 want of a better name we have called this a ''Plasterer's 
 Oval, ' ' for the reason that plaster lends itself more read- 
 ily than any other material to the formation of circular 
 mouldings. No one in the building trades can form a 
 circle or an oval moulding so quickly and accurately as 
 a plasterer. The method of setting out and of con- 
 structing this form of oval is as follows : To set out an 
 oval to a given size, the greater diameter being given. 
 Take this greater diameter as a base to determine the 
 required diameters of the large and small circle mould- 
 ings, M and N, Fig. 2. Let the line A B, Fig. 1, be the 
 given diameter, say 3 feet; on this form two squares, 
 each according to their diameter would be 1 foot 6 inches 
 by 1 foot 6 inches, as shown at C D E F and F G H C ; 
 then draw diagonals in each square as at C E and D F 
 and C G and F H and at their intersections 1 and 1 as 
 centres draw the circles 1 K and 1 K. The radius in this 
 example would be 9 inches. The quadrants M and M 1 
 correspond with the same letters in Figs. 2 and 3, and 
 they form the two ends of the oval. After this take C as 
 a centre, and with a radius from C to 0 at E or G de- 
 scribe that part of the circle L from 0 L 0, which forms 
 the upper side of the oval ; now take F as a centre, and 
 with the same radius describe the lower side, joining K K 
 at 0 and 0, thus forming the plan of the oval as shown 
 by the line ALB, and the dotted line below C It will be 
 
METHODS OF WORK 
 
 231 
 
 seen that the respective centres to describe this figure 
 give the centres and diameters to run the two circle 
 mouldings from which the ovals are formed. 
 
 To construct the oval, first make a running mould to 
 the desired profile, using a radius-rod in the usual man- 
 ner, for running circles on the flat. Before running the 
 mouldings, set out tw^o lines at right angles on the mould- 
 ing board, taking care to extend the lines a little be- 
 yond the outline of the large circle, as shown by the 
 dotted lines (Fig. 2). The extended parts of these lines 
 act as guides for cutting the moulding into exact quad- 
 rants. The intersection of them is the centre from 
 which both circles are run. Apply the running mould, 
 and turn it round, so that it leaves a faint mark on the 
 running board to indicate the width of the moulding to 
 be run. The width can also be marked by the aid of a 
 pencil, holding it at the outside member, and turning the 
 mould round, repeating this operation on the inside mem- 
 ber. On this space drive in eight tacks, two in each 
 quadrant, leaving the heads projecting about % inch. 
 The object of these tacks is to prevent the moulding 
 from lifting owing to plaster swelling, or from moving 
 round while being run. Cover the tacks with clay to 
 allow the moulding to be freely taken up after it is run 
 and cut. The moulding is then run in the usual way, 
 and is cut into four quarters, or quadrants. This is 
 done by applying two set-squares, one inside and one 
 outside of the moulding ; and at one of the quarter lines 
 lay a straight-edge over the moulding and against the 
 set-squares. The moulding can then be marked or sawn 
 at the proper place and angle. The dotted or quarter 
 lines divide the mouldings into quadrants, and give the 
 angles for cutting them. 
 
232 CEMENTS AND CONCRETES 
 
 The use of extending the lines beyond the moulding 
 will here be seen. A part may be obliterated while the 
 moulding is being run, bu.t the extended part will af- 
 ford a correct guide for the outside set-square. If the 
 quadrants are cut fine, square, and clean, the joints will 
 be scarcely perceptible when the four segments are 
 placed together. When this circle is cut and taken off 
 the board, the radius has to be altered to exactly one- 
 half of the large circle, and the small circle is run and 
 cut precisely in the same way as the large one. The four 
 quadrants can now be fixed to form an oval, as shown 
 in Fig. 3. If a quantity of oval mouldings be required, 
 a casting mould can be taken off this oval in which they 
 may be cast. It will be seen that the quadrants M and 
 N 1 form the sides of the oval in Fig. 3, and the quad- 
 rants M and M 1 form the ends. It will also be seen that 
 after completing this oval there are four quadrants left 
 to form another oval. If but one oval is required, run 
 only one-half of each circle, allowing a little space 
 beyond the centre line, so that a square and clean joint 
 can be cut. A thin saw with fine small teeth should be 
 used for this purpose. 
 
 Fig. 3 shows the four segments of the moulding in 
 position forming the oval. In this figure the moulding 
 is struck on the outside of the setting-out circle line, as 
 shown in Fig. 1, but the moulding in Fig. 2 is struck on 
 the inside of the setting-out lines. This is simply to 
 show that the same centres can be used for mouldings 
 struck on either side of the lines. A mould for casting 
 oval mouldings, also templates, can also be made by the 
 above process. For this purpose a reverse running 
 mould must be used for running the two circles. A 
 plaster piece mould for casting oval mouldings that are 
 undercut may also be formed by this method. In this 
 
METHODS OP WORK 
 
 233 
 
 case the running* mould must be made and used as de- 
 scribed for ' ' reverse moulds. ' ' 
 
 Coved Ceilings. — Coves to ceilings are of various 
 heights, as one-third, one-fourth, one-fifth, &c., of the 
 whole height. The form of the cove is generally either 
 a quadrant of a circle or of an ellipsis, taking its rise a 
 little above the cornice, and finishing at the crown or 
 other moulding. If the room is low in proportion to its 
 width, the cove must likewise be low; and when it is 
 high, the cove must likewise be so; by which means the 
 excess of height will be rendered less perceptible. An 
 example of two coved ceilings (from designs by James 
 Gibbs) are shown is the annexed illustration No. 22. 
 Fig. 1 shows the plan and elevation of a coved ceiling, 
 with circular windows between the groins. Fig. 2 shows 
 the plan and elevation of a coved ceiling, the design of 
 which is less intricate than that of Fig. 1. The curve 
 of this cove is a quadrant of a circle, as shown by the 
 section at the side. The plans will enable the section 
 of each design to be understood, and vice versa, and the 
 whole will render the method of constructing coves and 
 circular mouldings on circular surfaces (which is given 
 hereafter) to be more clearly understood. The external 
 and internal angle mouldings in these coves may be 
 formed with a jack template or as described for coves. 
 
 Circle Mouldings on Circular Surfaces, — The accom- 
 panying illustration, Plate III, is given to elucidate 
 various methods of running circular mouldings on cir- 
 cular surfaces, shows the elevation of a cove suitable for 
 an aquarium or marine hall. The external angle rib 
 moulding, C, and the panel rib moulding, D, spring from 
 the top or weathering of a main moulding, and intersect 
 with a horizontal or crown moulding at the top of the 
 cove. The section of the horizontal moulding is shown 
 
METHODS OF WORK 
 
 235 
 
 at G, and the section of the panel moulding is shown 
 above D ; the section of the external rib being of course 
 double that of the panel moulding. Where circular or 
 straight mouldings intersect with each other, it is ad- 
 v^antageous in most cases to run the circular mouldings 
 first, so that the whole of the moulding can be run, 
 and leave the intersection to be mitred on the 
 straight part, which is naturally the easiest part. In 
 some examples it is not advisable to run the circular part 
 first. For example, if the crown or horizontal moulding, 
 as shown at G, Fig. 1, was the lower part of a large 
 crown moulding made to intersect with small cove 
 mouldings, it would be best to run the straight moulding 
 first, and then cut away as much of the straight mould- 
 ing as will allow the nib of the running mould to pass 
 while running the circular moulding. For the section 
 in this example there would be very little mitring to do, 
 as it would simply be a butt mitre up to the back of the 
 circular mouldings. The external rib moulding, C, is 
 best run with a jack template. The circular panel 
 mouldings (one-half of a moulding is shown at D) can 
 be run by two methods. By the first, the moulding is 
 run in three parts, using a sledge-slippered running 
 mould fixed on a hinged radius-rod, and the two straight 
 parts are run from running rules. By the second 
 method, the whole moulding is run at one operation by 
 using a fibrous plaster template, made as already de- 
 scribed. 
 
 Forming Niches. — Niches are recesses formed in walls, 
 sometimes for the purpose of placing some ornamental 
 object in them, such as statues, vases, &c., and they are 
 often constructed in thick walls in order to save mate- 
 rials. The plans or bases of niches are generally semi- 
 circular, but some partake of all the segments under a 
 
236 CEMENTS AND CONCRETES 
 
 semicircle, while others are elliptical, and in a few in- 
 stances they are square or rectangular. The elevations 
 of niches are generally in accordance with their plans, 
 but variations from this Tule are sometimes met with. 
 The crown or heads of niches are generally plain, but 
 they are sometimes enriched with scalloped shells, &c., 
 or panelled with mouldings. With respect to the pro- 
 portion of niches, there is no fixed rule, but the general 
 one is twice and a half their width for their height. 
 Various methods are employed in the formation of 
 niches. The crowns of circular niches are generally run 
 with a mould, because being circle on circle and small 
 in surface, it is difficult to finish them true and smooth 
 by hand. 
 
 The accompanying illustration (No. 23) elucidates 
 two methods of forming semicircular niches with the aid 
 of running moulds. Fig. 1 shows the elevation, and Fig. 
 2 the section of the crown and a part of the body of 
 niche, with the centre-boards and moulds in position 
 when forming the crown of the niche. Fig. 4 shows the 
 section of the body of the cove, with the mould in posi- 
 tion when forming same. By the first method the niche 
 is formed in two operations, and by the second method 
 it is formed in one operation only. For the first method, 
 cut a running mould to the section of the niche, as shown 
 at B, Fig. 1, then fix it on the centre board, A, with two 
 hinges, keeping the upper surface or mould plate level 
 with the top edge of the centre board, as shown on the 
 section of the niche. Fig. 2. This also shows the end 
 section of the centre-board and the mould, with the 
 mould plate and a hinge. The dotted line indicates the 
 distance the mould travels. After this, fix the com- 
 bined centre-board and mould on the wall, taking care 
 that the top edge of the centre-board is level and ex- 
 
METHODS OF WOEK 
 
 237 
 
 Forming Niches with Running MoutDS. 
 
 NO. 23. 
 
238 CEMENTS AND CONCRETES 
 
 actly at the springing of the crown, C. The face of the 
 wall must be floated plumb, and an allowance made by 
 means of dots for the thickness of the setting coat be- 
 fore the centre-board is fixed. After the crown is fin- 
 ished, the centre-board and running mould is taken off 
 the wall and separated. The mould is then horsed with 
 two slippers to allow of its running the body or vertical 
 part of the niche. The mould works on a running rule 
 fixed on one of two screeds which are formed on the face 
 of the wall, one on each side of the opening. Care must 
 be taken that the screeds are plumb with the centre-board 
 dots. Fig. 3 shows an elevation of the mould when 
 horsed. B is the mould, D is a connecting board on 
 which the mould is fixed by means of the cleats, C, C, 
 and F, F, are the slippers. Fig. 4 shows an end section 
 of the horsed mould in position when running the body 
 of the niche. The base is finished by hand. 
 
 By the second method the niche is run in one opera- 
 tion, as already mentioned. This is effected by cutting 
 a running mould to the vertical section of the niche, then 
 fixing a pivot at the bottom and a bolt at the top. A 
 wood block, with a socket to fit the bolt on the mould, is 
 let into the face of the wall at the top of the nichC;, and 
 temporaril}^ fixed, then another block with a socket to fit 
 the pivot of the mould is fixed at the bottom of the 
 niche. Care must be taken that the sockets are plumb 
 and in a line with the centre of the niche, also that they 
 are in a line with the face of the wall^ so as to allow 
 the mould to form a true semicircle with perpendicular 
 arrises. Place the pivot of the mould in the socket, and 
 push the bolt up and secure it, and the mould is ready 
 for working. 
 
 Fig. 5 shows a section of the niche with the mould in 
 position. A is the mould with the pivot and bolt, and 
 
METHODS OF WORK 
 
 239 
 
 B, B, are the socket blocks. A plan of the niche and 
 mould is shown at Fig. 6. This also shows the plan of 
 the pivot block, and a board which is sometimes used to 
 secure the block. The dotted line indicates the dis- 
 tance the mould travels. When there are splays or beads 
 on the angle of the niche, the crown part is run with a 
 radius-rod mould from a centre-board, and the vertical 
 parts with a ^^twin-slipper running mould'' on running 
 rules fixed on the wall screeds, or with a nib running 
 mould on a slipper and a nib running rule. 
 
 The vertical parts of the beads or splays may also be 
 run with the mould shown in Fig. 3. For this purpose 
 two plates cut to the desired section must be fixed on the 
 mould, one at each side. The crown part is run with a 
 radius-rod, as already mentioned. The crown surface 
 and the angle moulding can also be run in one operation. 
 This is effected by cutting a mould plate to the section of 
 the moulding, including the section of the crown sur- 
 face, then horsing it with a slipper to run on the wall 
 surface, and a pivot to fit a socket formed in a centre- 
 board, or with a radius-rod to work on a centre-board. 
 A pivot will be found most suitable for small work and 
 a radius-rod for large work. In either case they must 
 be fixed on the centre of the mould, so as to be in a line 
 with the mould plate. After the crown is run, the mould 
 plate of the crown surface is cut off^ and the remaining 
 part of the mould used for running the vertical mould- 
 ings. 
 
 In some designs a small moulding, such as an impost 
 moulding, is carried round the body surface of the niche, 
 and in a line with the springing of the crown. This 
 moulding can be run in a similar way as shown at Fig. 
 5, or by fixing a flexible wood or a plaster running rule 
 on the body of the niche for the mould to run on. 
 
240 
 
 CEMENTS AND CONCRETES 
 
 The crowns of niches that are parallel with small 
 mouldings are best executed by making a model of the 
 design, then moulding it and casting, and fixing as many 
 as are required. In niche crowns that are enriched 
 with shells, foliage, &c., the enrichment should be cast 
 with the crown surface as a background. Fibrous plas- 
 ter is well adapted for the construction of niches. For 
 this purpose a reverse casting mould should be employed 
 for forming the casts. This is made by cutting a re- 
 verse running moidd to the section of the niche, and after 
 a sufficient length of the body is run, cut the mould in 
 half and run the crown. Then fix it on the end of the 
 run body, and then fix rules at the sides and ends to 
 form fences and rims, thus completing the casting 
 mould. 
 
 Any of the above methods for forming niches with 
 running moulds can be advantageously used for forming 
 the body and crown of the Ionic niche when such is re- 
 quired. 
 
 EuNNiNG AN Elliptical Moulding in Situ. 
 
 In No. 24 a method of running an elliptical curve with 
 a trammel is shown. Fig. 1 represents the front eleva- 
 tion of the trammel mounted and in working order, and 
 Fig. 2 is a section of the same. 
 
 Take two floor boards, B, long enough to reach to the 
 springing line of the arch, and nail them on the back of 
 two lengths of 5 in. by 2 in.. A, which, as shown may be 
 somewhat longer. Fix these up inside the jambs of the 
 opening, taking care to see that they are perfectly up- 
 right, and keep them the thickness of the trammel boards 
 (which is 1 in.) back from the face of the opening on 
 which the architrave is to be. Then cut three pieces of 
 
METHODS OF WORK 
 
 241 
 
 5 in. by 2 in., C, tight in between and secure them in 
 place with 3 in. cut nails, taking care to see that the 
 bottom side of the top one is above the springing line. 
 Then prepare the trammel boards, D and E, 6 in. by 1 
 
 PLASTEEERS TRAMMEL £0R ELLIFTIGAL ARCHITRAVE.' 
 
 NO. 24. 
 
 in., and cut the slots, which are % in. wide and of a 
 length which may be easily ascertained by simple geom- 
 etry. Halve the boards together at the joint and fur- 
 ther secure them by screwing a plate of the thickest sheet 
 zinc obtainable on the back, as per Fig. 3. Nail the 
 
242 CEMENTS AND CONCRETES 
 
 boards up as shown, keeping the horizontal slot central 
 on the springing line and the vertical slot exactly in the 
 centre of the opening, and be most particular to see that 
 the whole lot is perfectly upright and level. Next pre- 
 pare the trammel stick, 2 in. by 1 in., and mount the 
 mould on the top in the usual manner, as shown. Then 
 insert the pins in holes bored in the stick and secure by 
 a screw through the edge. Have them just thick enough 
 to work comfortably in the slots, and keep the centre of 
 the pin XI, the distance of the rise, and the centre of 
 the pin X2, the distance of the half sp^n from the bot- 
 tom member of the architrave. All the timber may be 
 deal except the pins, which must be of some kind of hard 
 wood. If well made and used with care this trammel 
 ought to serve many times ; the pins, of course, needing 
 adjustment for arches of different size. 
 
MISCELLANEOUS MATTERS. 
 
 Depeter, — This is a sort of a rough-cast, and consists 
 of forming a fair surface with coarse stuff or Portland 
 cement. As soon as laid a hand-fiaat is parred over the 
 surface a few times to give it an even and uniform tex- 
 ture, and while it is soft, pressing in by hand, small 
 pieces of hard coal, broken bottles^ pottery, bricks, shells, 
 stones, pebbles, or marble. The design may be varied and 
 enriched by using various colored pieces in forming mar- 
 gins, bands or other ornamentation. On the contrast of 
 colors and the broad bands depends the effect of this 
 class of work. A combination of ^'Depeter" and rough- 
 cast may be used with excellent effect. 
 
 Sgraffitto. — Sgraffitto or ^^graffitto'' is an Italian word, 
 and means scratched." Scratched decoration is the 
 most ancient mode of surface decoration employed by 
 man. The primitive savage of the flint-weapon period 
 used this simple form of ornamentation. Scratched 
 work, a;s used by prehistoric man, may be fitly termed 
 the proem of the civilized arts of drawing, modelling and 
 sculpture. The term is now employed for plaster deco- 
 rations, scratched or incised upon plaster or cement be- 
 fore it is set. It may be used for both external and 
 internal decoration. The annexed illustrations (Nos. 25 
 and 26) will demonstrate the high degree to which the 
 art of sgraffitto attained in Italy. 
 
 Some graffittos are really low relief work rather than 
 the sgraffitto, they being very deep cut with the iron or 
 steel point, which was necessitated by the final coat be- 
 ing plastered on instead of washed on. Deep cutting 
 
 243 
 
MISCELLANEOUS MATTERS 245 
 
 gives a hard appearance to the design, prevents the water 
 from running off the walls, and catches the dirt. In exe- 
 cuting true sgraffitto, the cut or scratch should be ex- 
 ceedingly slight — in fact, some parts scarcely percepti- 
 ble. 
 
 Sgraffitto decorations do not suffer materially from 
 stubbing it with an old broom, leaving it barely half an 
 inch from the finished face. For internal work, the ordi- 
 nary pricking up suffices. When this is dry, a thin coat 
 of selentic lime mixed with the desired coloring matter 
 for the background, is floated over it. This background 
 may be black, bone-black being used ; red, for which use 
 Venetian or Indian red, or the ordinary purole brown 
 of commerce, singly or mixed, to produce any tone de- 
 sired; yellow, produced by ochres or umbers; blue, by 
 German blue, Antwerp blue, or any of the commoner 
 blues, avoiding cobalt, and these colors you may use to 
 any degree of intensity or paleness. When this coat is 
 nearly dry, skim over it a very thin coat of pure selentic 
 lime, which dries of a parchment color and generally 
 suffices. If you want a pure white lime, use a moderate 
 quick-setting one, as stiff as you can work it, and as 
 each variety of lime has its own individual perversity, I 
 can give no general direction, and would advise the be- 
 ginner to stick to selentic, which is always, procurable. 
 You have, of course, prepared your cartoon. This is 
 pricked and pounced as for any other transfer process, 
 and then with an old, well-worn, big-bladed knife, for 
 there is no better tool, you can cut round all the out- 
 lines, and with a flat spatula clear away all the thin 
 upper coat, leaving the colored ground as smooth as you 
 can. If your plaster is not quite dry enough for the 
 two coats to separate easily, wait a little longer, but not 
 too long, for that is fatal. By the time you have cleared 
 
246 CEMENTS AND CONCRETES 
 
 out your background, the plaster will be in a good con^^ 
 dition to allow you to cut out the finer parts of the de- 
 sign, such as folds of the draperies, or the finer lines of 
 the faces or of the ornament. Use your knife slightly 
 on the slope, and if you want to produce half-tones, slope 
 it very much; but, as a rule, the more you avoid half- 
 tones, and the simpler and purer your line, the more 
 effective your work will be. Recollect, above all things, 
 you are making a design and not a picture, and you 
 must never hesitate, for to retouch is impossible. Some- 
 times it may be desirable to gild the background, and 
 you can then carve or impress it with any design you 
 choose. It occasionally happens you want to give some 
 semblance of pictorial character to your work when it is 
 small in scale and near the eye, and then you can pro- 
 ceed as though you were cutting a wood-block. 
 
 By cutting out your ground color in places, and 
 plastering it with that of another color, you may vary 
 any portion of it you desire: You can also wash over 
 certain parts of your upper coat with a water-color if 
 you desire, combining fresco with the sgraffitto, both of 
 which manners are often used ; but, as a rule, the broader 
 your design, and the simpler your treatment of it, the 
 better. It will be seen that this process is very available 
 for simple architectonic effects; and for churches, hos- 
 pitals, and other places where large surfaces have to be 
 covered, it is the least costly process that can be adopted. 
 It has also the great advantage of being non-absorbent, 
 and it can be washed down at any time. The artist is 
 untrammelled by difficulties of execution, but he should 
 bear in mind that the more carefully he draws his lines 
 and the simpler he keeps his composition, the more 
 charmed with the process he will be, and the better will 
 be the effect of his work. 
 
MISCELLANEOUS MATTERS 247 
 
 A well-known artist records his experience of sgraffitto 
 as follows: 
 
 '^Rake and sweep out the mortar joints, then give the 
 wall as much water as it will drink, or it will absorb 
 the moisture from the coarse coat, as it will not set, but 
 merely dry, in which case it will be' worth little more 
 than dry mud. Care should be taken that the cement 
 and sand which compose the coarse coat should be prop- 
 erly gauged, or there may be an unequal suction for the 
 finishing coats. The surface of the coarse should be 
 well roughened to give a good key, and it should stand 
 some days to thoroughly set before laying the finishing 
 coat. When sufficiently set, fix your cartoon in its des- 
 tined position with nails; pounce through the pricked 
 outline; remove the cartoon; replace the nails in the 
 register holes; mark with chalk spaces for the different 
 colors, as indicated by the pounce impression on the 
 coarse coat; lay the several colors of the color coat ac- 
 cording to the design as shown by the chalk outlines; 
 take care that in doing so the register nails are not dis- 
 placed ; roughen the face in order to make a good key for 
 the final coat. When set, follow on with the final sur- 
 face coat, only laying as much as can be cut and cleaned 
 up in a day. When this is sufficiently steady, fix up the 
 cartoon in its registered position; pounce through the 
 pricked outline ; remove the cartoon, and cut out the de- 
 sign in the surface coat before it sets; then if the regis- 
 ter is correct, cut through to different colors, according 
 to the design, and in the course of a few days the work 
 should set as hard and as homogeneous as stone, and as 
 damp-proof as the nature of things permit. 
 
 * ^ When cleaning up the ground of color which may be 
 exposed, care should be taken to obtain a similar quan- 
 tity of surface all through the work, so as to get a broad 
 
248 CEMENTS AND CONCRETES 
 
 effect of deliberate and calculated contrast between the 
 trowelled surface of the final coat and the scraped sur- 
 face of the simple' contrasts of light against dark, or 
 dark against light. The following are the proportions 
 of the various coats : 
 
 ' ' Coarse coats : One of Portland cement to 3 of washed 
 sharp coarse sand. 
 
 ' ' Color ccat : One and one-half of air-slaked Port- 
 land to 1 of color laid % inch thick. Distemper colors 
 are Indian red, Turkey red, ochre, umber, lime blue; 
 lime blue and ochre for green; oxide of manganese for 
 black. In using lime blue, its violet hue may be over- 
 come by adding a little ochre. It should be noted that 
 it sets much quicker and harder than the other colors 
 named. 
 
 Final coat, internal work: Parian, air-slaked for 
 twenty-four hours to retard its setting, or fine lime and 
 selenitic sifted through a fine sieve. 
 
 ''For external work: Three selenitic and 2 silver 
 sand. 
 
 ''When finishing, space out the wall according to the 
 scheme of decoration, and decide where to begin, and 
 give the wall in such place as much water as it will 
 drink; then lay the color coat, and leave sufficient key 
 for the final coat. Calculate how much surface of color 
 coat it may be advisable to get on to the wall, as it is bet- 
 ter to maintain throughout the work the same duration 
 of time between the laying of the color coat and the fol- 
 lowing on with the final surface coat; for this reason, 
 that if the color sets hard before laying the final coat, it 
 is impossible to get up the color to its full strength wher- 
 ever it may be revealed in the scratching of the decora- 
 tion. When the color coat is quite firm, and all shine 
 has passed away from its surface, follow on with the 
 
MISCELLANEOUS MATTERS 249 
 
 final coat, but only lay as much as can be finished in one 
 day. The final coat is trowelled up, and the design 
 is incised or scratched out. Individual taste and experi- 
 ence must decide as to thickness of final coat, but if laid 
 between % inch and 1-12 inch, and the lines cut with 
 slanting edges, a side light gives emphasis to the fin- 
 ished result, making the outlines tell alternately as they 
 take the light or cast a shadow." 
 
 Another methcd which I have used in sgraffitto for 
 external decoration was done entirely with Portland 
 cement. This material for strap-work or broad foliage, 
 or where minuteness of detail is unnecessary, will be 
 found suitable for many places and positions. Three 
 colors may be used if required, such as black for the 
 background, red for the middle coat, and grey or white 
 for the final coat. These colors may be varied and sub- 
 stituted for each other as desired, or as the design dic- 
 tates. The Portland cement for floating can be made 
 black by using black smithy ashes as an aggregate, and 
 by gauging with black manganese if for a thin coat. The 
 red is obtained by adding from 5 to 10 per cent, of red 
 oxide, the white by gauging the cement with white mar- 
 ble dust, or with whiting or lime, the grey being the nat- 
 ural color of the cement. After the first coat is laid, 
 it is keyed with a coarse broom. The second coat is laid 
 fair and left moderately rough with a hand-float. The 
 suction of the first coat will give sufficient firmness to 
 allow the third coat to be laid on without disturbing the 
 second. The third coat should be laid before the sec- 
 ond is set hard. The second and third coats may be 
 used neat, or gauged with fine sifted aggregate as re- 
 quired. The finer the stuff, the easier and cleaner the 
 work, and the cut lines are more accurate and free from 
 jagged edges. The outlines of the design may be 
 
250 CEMENTS AND CONCRETES 
 
 pounced or otherwise transferred to the surface of the 
 work, and the details put in by hand. The thickness of 
 the second coat should be about 3-16 inch, and the third 
 coat about % inch. The thickness of one or both coats 
 may be varied to suit the design. The beauty of effect 
 of this method of linear decoration, aided by two or 
 three colors, depends greatly on the treatment of design, 
 the clearness of the incised lines, and the pleasing color 
 contrasts. It will be seen that in the three methods 
 described there is a similarity, yet the method of using 
 two color coats on a dark floating coat will give more 
 variety and effect. There is a large use for sgraffitto in 
 the future, as it has been in the past, and its use is inti- 
 mately bound up with the future of cement concrete. 
 
 In order that the foregoing examples of high-class 
 sgraffitto may not deter the young plasterer from trying 
 his ' ' 'prentice han ' " in this class of work, some simple 
 designs are given in the annexed illustration (No. 27). 
 Fig. 1 shows a design for a frieze in two colors. The 
 ground may be black or red, and the ornament buff or 
 grey. The colored material for the ornament is laid 
 first, and the colored material for the ground laid last. 
 Pig. 2 shows a design for a cove in two colors, one with 
 two shades. The ground is grey, and the band work 
 buff. A deeper shade of buff for the honeysuckle can be 
 obtained by brushing this part with liquid color made 
 deeper than the original gauge, also by laying a black 
 coat first, and in a line with the honeysuckle ; then laying 
 the buff stuff for the band work next, and then laying 
 the grey color last. In the latter case the honeysuckle 
 is cut deeper than the band work, so as to expose the 
 black coat. 
 
 Different effects can be obtained by changing the col- 
 
MISCELLANEOUS MATTERS 251 
 
 ors. Sections of the surface of the frieze and part of the 
 moulding are shown at the ends. 
 
 Fresco, — The plasterer is closely allied to the artist 
 painter. He has always to be in readiness to plaster the 
 wall for the artist. Owing to the alliance with distin- 
 guished artists, and the various methods of preparing 
 and using the plaster materials, I am induced to give a 
 few notes, also extracts from writers of authority. 
 
 -Sgraffitto Frieze in Two Cx^lours. 
 NO. 27. 
 
 Fresco is a mode of painting with water-colors on freshly 
 laid plaster while it remains naturally wet. It is called 
 ''fresco" either because it was originally used on build- 
 ings in the open air, or because it was done on fresh 
 plaster. Fresco is an ancient art, being mentioned by 
 
252 CEMENTS AND CONCRETES 
 
 Pliny. Mr. Flinders Petrie found some remarkably fine 
 specimens on floors and walls at Tel-el- Amarna, which 
 reveal the state of the art four thousand years ago. Fine 
 frescoes were discovered in the ruins of Pompeii. In 
 one of the principal houses the plaster walls are adorned 
 with theatrical scenes; in an inner room is the niche 
 often to be seen in Pompeiian houses. The frescoes on 
 the wall consist of floral dados. Above this is a whole 
 aquarium, with shells, plants, birds and animals. They 
 are, all executed in their natural colors, and are natur- 
 ally and gracefully drawTi. Michael Angelo's beautiful 
 fresco on the ceiling of the Sistine Chapel in the Vatican 
 is grand both in conception and execution. It measures 
 133 feet in length by 43 feet in width. Eaphael's fres- 
 coes in the Vatican, Farnesina Palace, &c., are wonder- 
 fully fine, and may be regarded as the high-water mark 
 of Cinque Cento decoration. 
 
 For fresco or buon fresco the lime has to be care- 
 fully run, and the sand should be white, clean, and of 
 even grain, being well washed and sifted to free it from 
 impurities or saline properties. Silver sand is pre- 
 ferred by some artists. The older the putty lime, the 
 better the results. The lime is slaked in a tub, and then 
 run through a fine wire sieve into a tank, and after being 
 covered up, is left for three months. It is then put into 
 the tub again, and re-slaked, or rather well worked, and 
 run through a fine hair sieve into earthenware jars or 
 slate tanks, and the water which collects at the top drawn 
 or poured off, the jars or tank being covered over to ex- 
 clude the air. Lime putty in this state will keep for an 
 indefinite time without injury. From 2 to 4 parts of 
 sand to 1 part putty is usual. Marble dust alone is 
 sometimes used in place of sand, and also sand with 
 equal parts. Every difference of lime and sand found 
 
MISCELLANEOUS MATTERS 253 
 
 in various localities should be considered and tested be- 
 fore using. A soft sand is quickly dissolved by a 
 strong lime, and a plaster made of this is fit for use 
 sooner, and will deteriorate more quickly than a plaster 
 made with a less powerful lime and a harder sand, or 
 with marble dust. 
 
 The wall surface to be plastered must be well scraped 
 and hacked, the joints raked out and brushed, and the 
 whole surface well scrubbed and wetted. The rendering 
 is done with the best possible prepared old coarse stuff. 
 If the walls are rough or uneven, they should be first 
 pricked up and then floated. In any case, the surface 
 is left true, and with a rough face, to receive the fin- 
 ishing coat. Portland cement or hydraulic lime gauged 
 with sand, also gauged with coarse stuff, has been used 
 where the walls were damp (damp is fatal to fresco), 
 or if exposed to the atmosphere. When Portland cement 
 or hydraulic lime is used, the work should be allowed to 
 stand until thoroughly dry to allow any contained sol- 
 uble saline efflorescence to come to the surface. This is 
 brushed off with a dry brush, and a few days are allowed 
 to elapse to see if there is a further efflorescence. When 
 this is all extracted and swept off, and the artist is ready 
 to commence, the wall is washed with a thin solution of 
 the fine setting stuff, and then laid about % inch thick, 
 with well-beaten, worked, and tempered fine setting 
 stuff. It is then rubbed with a straight-edge and scoured 
 with a hand-float (using lime water for scouring) until 
 the surfacei is true and of uniform grain. Most artists 
 prefer a scoured surface without being trowelled. No 
 more surface should be covered than can be conven- 
 iently painted in one day. While the plaster is still 
 soft and damp, the cartoon iis laid on, and the lines and 
 details pounced in or indented by means of a bone or 
 
254 CEMENTS AND CONCRETES 
 
 hard-wood tool. Should the finishing coat get too dry 
 in any part, it can be made fit for work by using a fine 
 spray of water. The method of plastering and the gaug- 
 ing of materials may slightly vary according to the de- 
 sire of the painter and the kind of fresco in hand. The 
 following is taken from an old manuscript dated 1699 : — • 
 
 '^1. In painting the wall to make it endure the 
 weather, you must grind colors with lime water, milk, or 
 whey, mixed in size. 
 
 ''2. Then paste or plaster must be made or well- 
 washed lime, mixed with powder of old rubbish stones. 
 The lime must be often washed till finally all the salt is 
 extracted, and all your work must be done in clear and 
 dry weather. 
 
 '^3. To make the work endure, stick into the wall 
 stumps of headed nails, about 5 or 6 inches asunder, and 
 by this means you may preserve the plaster from peeling. 
 
 "4:. Then with the paste plaster the walls a pretty 
 thickness, letting it dry; but scratch the first coat with 
 the point of your trowel longways and crossways, as 
 soon as you have done laying on what plaster or paste 
 you think fit, that the next plastering you lay upon it 
 may take good key, and not come off nor part from the 
 first coat of plastering; and when the first coat is dry, 
 plaster it over again with the thickness of half a barley- 
 corn, very fine and smooth. Then, your colors being al- 
 ready prepared, work this last plastering over with the 
 said colors in what draught or design you please — his- 
 tory, etc.,t — so will your painting unite and join fast to 
 the plaster, and dry together as a perfect compost. 
 
 '^Note — ^Your first coat of plaster or paste must be 
 very haired with ox-hair in it, or else your work will 
 crack quite through the second coat of plastering; and 
 will spoil all your painting that you paint upon the sec- 
 
MISCELLANEOUS MATTERS 255 
 
 end coat of plastering; but in the second coat that is 
 laid on of paste or plaster there must be no hair in it at 
 all, but made thus: — 
 
 Mix or temper up with well-washed lime, fine powder 
 of old stones (called finishing stuff) and sharp grit sand, 
 as much as you shall have occasion for, to plaster over 
 your first coat, and plaster it all very smooth and even, 
 that no roughness, hills, nor dales, be seen, nor scratch of 
 your trowel. The best way is to float the second coat of 
 plastering thus: — After you have laid it all over the 
 first coat with your trowel as even and smooth as pos- 
 sible, you can then take a float made of wood, ver^^ 
 smooth, and 1 foot long and 7 or 8 inches wide, with a 
 handle on the upper side of it to put your hand into 
 to float your work withal, and thus will make your 
 plastering to lie even; and lastly, with your trowel you 
 may make the said plastering as smooth as possible. 
 
 ''5. In painting be nimble and free; let your work 
 be bold and strong; but be sure to be exact, for there is 
 no alteration after the first painting, and therefore 
 heighten your paint enough at first; you may deepen at 
 pleasure. 
 
 ^^6. All earthy colors are best, as the ochres, Spanish 
 brown, terra-vert, and the like. Mineral colors are 
 naught. 
 
 ^'7. Lastly, let your pencil and brushes be long and 
 soft, otherwise your work will not be smooth; let your 
 colors be full, and flow freely from the pencil or brush; 
 and let your design be perfect at first, for in this there 
 is no alteration to be made." 
 
 Fresco Secco. — Closely allied with the genuine fresco 
 (fresco buono) is another kind called fresco secco (dry), 
 or mezzo (half) fresco. The plaster work for fresco sec- 
 co is similar to that used for fresco buono. It is allowed 
 
256 CEMENTS AND CONCRETES 
 
 to stand until thoroughly dry. The surface is then 
 rubbed with pumice-stone, and about twelve hours before 
 the painting is commenced it is thoroughly wetted with 
 water mixed with a little lime. The surface is again 
 moistened the next morning, and the painting begun in 
 the usual way. If the wall should become too dry, it is 
 moistened with the aid of a syringe. There is no fear of 
 joinings in the painting being observable, and the artist 
 can quit or resume his work at pleasure. Joinings are 
 distinctly noticeable in the frescos in the Loggia of the 
 Vatican. Fresco secco paintings are heavy and opaque, 
 whereas real fresco is light and transparent. While the 
 superiority of fresco buono over fresco secco for the 
 hi.ghest clasis of decorative painting is unquestionable, 
 still the latter is suitable for many places and forms of 
 decorative paintings. The head by Giotto in the National 
 Gallery, from the Brancacci Chapel of the Carmine at 
 Florence, is in fresco secco. 
 
 Indian Fresco and Marble Plaster, — ^ 'Fresco painting 
 is a common mode of decoration in Jeypore, and is used 
 in ornamenting walls inside and outside of buildings — 
 also as a dado or border round the wainscot or on the 
 floor — and on any surface where decoration is desired. 
 The beautiful marble planter on which it is done is com- 
 mon Rajputana, and is used to line the surface of walls 
 or floors, and of baths or bath-rooms. It is admirably 
 adapted to places where coolness and cleanliness are de- 
 sired, and is very suitable to a warm climate. It would 
 no doubt be more commonly used if pure lime could be 
 obtained. 
 
 ' ' To prepare the marble plaster, the process in use in 
 Jeypore is as follows: — Take pure stone lime, mix 
 it with water until it has dissolved, then strain it through 
 a fine cloth. In Jeypore the lime is made from pounded 
 
MISCELLANEOUS MATTERS 257 
 
 marble chips or almost pure limestone. The substance 
 which remains in the cloth is called bujra, and all that 
 passes through the cloth is called ghole. These should 
 be prepared a few days before they are required so as 
 to allow time to settle, and every day the water should 
 be changed, so as to leave a very fine sediment. 
 
 ^^Jinki, which is also used, is pure marble ground to 
 a very fine powder; kurra is a mixture of bujra and 
 jinki; and jinkera is a mixture of ghole and kurra. 
 These are the materials used, and the names by which 
 they are known in Jeypore. In Madras, where similar 
 plaster is used, it is made, I believe, from shells and the 
 ingredients are probably known by other local names. 
 
 ^^If tlie surface to be polished is a slab or stone^ the 
 kurra mixture consists of 1 part by weight of burja and 
 1% parts of jinki. If the surface is a wall or a chunam 
 floor, it must be first thoroughly dry and consolidated- 
 then take equal parts of burja and jinki to form the 
 kurra mixture. Mix the burja and the jinki well to- 
 gether; add a little water and grind them well together, 
 in the same ways as natives mix their condiments, by 
 hand with a stone rolling-pin on a slab, until they form 
 a perfectly fine paste. Wet the surface which is to be 
 polished, and spread over it a layer of this kurra mix- 
 ture, about % inch thick. Then beat the surface gently 
 with a flat wooden beater, sprinkling a few drops of 
 clean water on the surface occasionally. Then mix a 
 little ghole with the kurra plaster (described above as 
 jinkera) and lay it on evenly with a brush as if it were 
 a coat of paint ; rub the surface over carefully with any 
 clo'se-grained flat stone, called in Jeypore jhaon. The ob- 
 ject of this is to smooth down all irregularity and 
 roughness, and to prepare a smooth even surface. 
 Sprinkle a few drops of water and repeat the process, 
 
258 CEMENTS AND CONCRETES 
 
 taking care that no hollow places are allowed to re- 
 main. Paint it over with fine jinkera (ghole and 
 kurra mixed), increasing the proportion of ghole, and 
 rub it down well with a flat stone (jhaon) as before; 
 then paint it over with ghole only, after each coat rub- 
 bing it down carefully with the jhaon stone. After this, 
 rub it all over with a soft linen cloth, called in Jeypore 
 nainsukh, folded into a pad. Then give it another coat 
 of ghole, and now rub it down carefully with a piece of 
 polished agate, called in Jeypore ghinti, until it begins 
 to shine. The surface must not be allowed to dry too 
 rapidly, or a good polish will not be obtained. Care 
 must be taken that the lime has been thoroughly slaked 
 in the first instance, or it may blister; also that the sur- 
 face, if a floor, is thoroughly consolidated^ as the least 
 settlement naturally causes the plaster to crack. The 
 polishing process with the agate cannot be repeated too 
 often; the more it is carefully done, the better will be 
 the polish. Every time the agate is moved backwards 
 it should be made to pass over a portion of its previous 
 course, so as to prevent any mark or line at the edge. 
 Lastly, if the surface is to remain white, take some water 
 which has been mixed with grated cocoanut, and lay it 
 on the surface. Let it dry, and then rub it down with a 
 fine cloth folded into a pad. If any coloring is desired, 
 the same process is adopted until the polishing with the 
 agate is begun. This is only done slightly. If any pat- 
 tern is desired, it is drawn on paper and pricked out. 
 The paper is placed on the surface, and is dusted with 
 very finely powdered charcoal tied up in a muslin bag. 
 The charcoal passes through the perforations and marks 
 the plaster surface. The paints are mixed with water, 
 and are painted on by h^nd while the surface is still 
 fresh and moist hence the term fresco. Where a large 
 
MISCELLANEOUS MATTERS 259 
 
 surface has to be done, it is necessary to employ several 
 men at the same time, in order that the surface might 
 be all painted before it has time to dry ; or else the pat- 
 tern must be so arranged that the connection of one 
 day^s work with the work of the next will not be amiss. 
 Immediately after the surface has been painted the 
 colors are beaten in with the back of a small trowel, in 
 such a manner that the color is not rubbed or mixed 
 with the color adjacent. As soon as it shows to the 
 touch that the color has become incorporated with the 
 plaster, the surface is painted over with water mixed 
 with grated cocoanut, and is then polished down with 
 the agate. 
 
 ^^The following colors can be used in process: — Lamp 
 black; red lead; green (from a stone known as hara 
 pathar) ; yellow (from a stone called pila pathar) ; 
 brown or chocolate. A little glue is mixed with the two 
 first colors, and gum only with the others. The colors 
 used are mostly earths or minerals, as other will not 
 stand the action of the lime. Vegetable pigments can- 
 not be used for this model of painting, even when mixed 
 with mineral pigments, and of the latter only these are 
 available which resist the chemical action of the lime. 
 The lime in drying throws out a kind of crystal surface 
 which protects the color and imparts a degree of clear- 
 ness superior to that of any work in tempera or size 
 paint. The process, although apparently simple, re- 
 quires dexterity and certainty of hand, for the surface 
 of the plaster is delicate, and the lime only imbibes a 
 certain quantity of additional moisture in the form of 
 liquid colors, after which it loses its crystallizing quality, 
 and the surface or a portion of it becomes rotten. It is 
 only after the lime has dried that such flaws are dis- 
 covered, and the only remedy is to cut away the de- 
 
260 CEMENTS AND CONCRETES 
 
 fective portion, lay on fresh plaster and do the work 
 over again. The colors become lighter after the plaster 
 dries, so allowance must be made for this. The advan- 
 tages which this process possesses are clearness, exhib- 
 iting the colors in a pure and bright state ; the surface 
 is not dull and dry as in tempera or size painting, nor 
 glossy as in oil painting; it can be easily seen from any 
 point, and it is not injured by exposure to the air; it 
 will stand washing, and can be cleansed with water with- 
 out injury/' 
 
 SCAGLIOLA. 
 
 Historical. — Scagliola derives its name from the use 
 of a great number of small pieces or splinters ; scagliole 
 of marble being used in the best description of this 
 work. It is said to have been invented in the early part 
 of the sixteenth century by Guido Sassi, of Cari, in 
 Lombardy, but it is more probable that he revived an 
 old process, and introduced a greater variety of colors 
 in the small pieces of marble and alabaster used to 
 harden the surface, and better imitate real and rare 
 marbles. It is sometimes called mischia from the many 
 mixtures of colors introduced by it. The use of colored 
 plaster for imitating marbles was known to the ancients, 
 although the pure white, or marmoratum opus and al- 
 hariim opus, mentioned by Pliny, was more used. The 
 plastic materials used by the Egyptians in coating the 
 walls of their tombs partook of the nature of marble. 
 The ancients also ased a marble-like plaster for lining the 
 bottoms and sides of their aqueducts, which has endured 
 for many centuries without spoiling or cracking. In the 
 decoration of their domes the Moors used colored 
 plasters, which have stood the ravages of time. The 
 
MISCELLANEOUS MATTERS 
 
 261 
 
 beautiful chunam or plaster of India, as used by the 
 natives, has a hard surface, takes a brilliant polish rival- 
 ling that of real marble, and has withstood for many 
 ages the sun and weather without sign of decay. The 
 roofs and floors of many houses in Venice are coated with 
 smooth and polished plaster, made at a later date, strong 
 enough to resist the effects of wear and weather, 
 without visible signs of crack or flaw, and without much 
 injury from the foot. Scagliola was largely employed 
 by the Florentines in some of their most elaborate works. 
 It has been used in France with great success for archi- 
 tectural embellishment. The rooms are so finished that 
 no additional work in the shape of house-painting is 
 required, the polish of the plaster and its evenness of 
 tint rivalling porcelain. Scagliola is the material used. 
 At times the surface of the plaster is fluted, or various 
 designs are executed in intaglio upon it in the most 
 beautiful manner. 
 
 Scagliola is one of the most beautiful parts of decora- 
 tive plaster work, and it is regrettable that there should 
 not be a greater revival of such a charming and beautiful 
 art. Its limited use in recent times is greatly owing to 
 its manufacture being restricted by rules and rigid 
 methods and even prejudices, and being confined to 
 monopolists, who kept the method secret until it was 
 looked upon as a mystery which greatly enhanced its 
 cost. But through the information now at hand, com- 
 bined with a little practical experience and enterprise, 
 there is no valid reason why architects should not adopt 
 it for second or even for third class buildings. It 
 possesses great beauty, and is capable of affording grand 
 effects and the richest embellishments in architecture. 
 Scagliola, in skilful hands, can be produced in every 
 variety of color and shade, in every possible pattern, in 
 
262 CEMENTS AND CONCRETES 
 
 every conceivable form and size, from a paper weight 
 to the superficial area of a large wall. It can be made 
 at a price that would enable it to take the place of the 
 most durable material now in use. Experience has 
 proved that it will last as long as the house it adorns, 
 and with an occasional cleaning, it will always retain its 
 polish and beauty. It has been produced in past days 
 in our own and other lands, and carried to such high ex- 
 cellence, that many of the precious marbles, such as 
 jasper, verd antique, porphyry, brocatello, giailo an- 
 tique. Sienna, etc., have been imitated so minutely, and 
 with an astonishing degree of perfection, as to defy de- 
 tection. It will not only retain its polish for years, but 
 can be renovated at much less comparative cost than 
 painting and varnishing marbled wood, or plaster work. 
 It is cheaper and more satisfactory to use scagliola in 
 the first instance than to go to the expense of plastering 
 walls, columns, etc., with Keen's or other kindred ce- 
 ments, used for their hardness and ready reception of 
 paint, which are to be afterwards marbled and var- 
 nished. Both are imitations, but painted marble can 
 never be compared with scagliola, which has the look, 
 color, touch, and polish of the more costly natural 
 marbles. 
 
 Various Artificial Marbles. — Various patents have 
 been taken out for the production of artificial marbles, 
 having for their bases plaster of Paris. These patents 
 will be briefly mentioned here. 
 
 Evaux 's Artificial Marble is composed of plaster mixed 
 with albumen and mineral colors, the ground being zinc 
 white. Rowbotham also employed plaster and albumen 
 soaked in a solution of tannic acid. Lilienthal makes 
 an artificial marble with Keen 's cement, slaked lime, and 
 curdled milk. 
 
MISCELLANEOUS MATTERS 263 
 
 Pick^s Neoplaster/^ — This composition was patented 
 in 1883, and is composed of 75 per cent, of plaster, mixed 
 with feldspar, marl, coke dust, and pumice-stone. Gule- 
 ton and Sandeman patented an artificial marble in 1876. 
 It is composed of Keen's cement backed with fibre, and 
 soaked or brushed on the back with a solution of as- 
 phalt. The slabs were made in glass moulds. La- 
 roque's patent marble is formed of plaster and alum 
 gauged with gum water, the veining being done with 
 threads of silk dipped in the required colors. The 
 backs of the slabs or panels are strengthened with can- 
 vas. 
 
 Mur Marble is composed of a mixture of Keen's and 
 Marin's cement in equal proportions, made into a paste, 
 with a solution of sulphate of iron and a small quanti- 
 ty of nitric acid in water. The slabs are dried and 
 tarred at a temperature of 250 degrees F. for about 
 twenty hours, and when cool are rubbed, colored, var- 
 nished, or japanned, as required. There is another 
 patent formed of plaster, gauged with a solution con- 
 taining tungstate of soda, tartaric acid, bicarbonate of 
 soda, and tartarate of potash. Another is composed of 
 Keen's cement 10 parts, ground glass 1 part, and alum 
 % part, dissolved in hot water. 
 
 Guattaris Marble is obtained by transforming gypsum 
 (sulphate of lime) into carbonate of lime (marble). 
 There are two methods. The first consists of dehy- 
 drating blocks of gypsum, and then hardening by im- 
 mersion in baths containing solutions of silicate of soda, 
 silicate of lime, chloride of lime, sulphate of potash, 
 soda, acid phosphate of lime, etc. The blocks are cut 
 into slabs or carved before being put into the bath. The 
 second method consists in dehydrating the gypsum, and 
 bathing in some of the above chemicals. They are then 
 
264 CEMENTS AND CONCRETES 
 
 dried and burnt at a red heat^ and allowed to cool. 
 After a second burning; and cooling, the products are 
 ground as for plaster. This powder is called '^Marmo- 
 rite''. The marmorite is gauged in a trough with some of 
 the water from the baths as above, kneaded into a paste, 
 and the colors added and mixed. The paste is then put in- 
 to moulds and pressed, and when set they are taken out, 
 dried, and finally polished. Mineral colors are used. 
 Yellow and its tints are obtained with citrate of iron 
 dissolved in oxysulphate of iron, sulphate of cadmium, 
 chloride of yttrium, chromate of lithium, and yellow of 
 antimony. Red and its tints are obtained with dragon's 
 blood, sesquioxide of iron, mussaride red, and sulphate 
 of didymium, and the salts derived from it, which give 
 a rose color. Azure blue is obtained with sulphate of 
 sodium mixed with acetate of copper and tartaric acid 
 and oxide of cobalt. Green and its tints are obtained 
 with verdigris, hydrochlorate of cobalt. Black is ob- 
 tained by pyrolignite of iron reduced by boiling in gallic 
 acid with sirco black. Black marble is also obtained 
 by immersing gypsum blocks or slabs or the cast mar- 
 morite in a hot preparation of bitumen. During this 
 operation the dehydration of the material under treat- 
 ment is accomplished, and the bitumen not only pene- 
 trates the mass, but fills up all the pores and spaces 
 evacuated by the water which was contained in the ma- 
 terial treated, and a hard mass of brilliant black is ob- 
 tained in every way equal to Flanders marble. It is 
 said that the above imitation marbles are largely used in 
 Florence. 
 
 Scagliola Manufacture. — Scagliola can be made in situ 
 or in the work shop, according to the requirements of the 
 work; but in either case it is necessary that the work 
 place should be kept at a warm temperature, and the 
 
MISCELLANEOUS MATTERS 265 
 
 work protected from dust or damp atmosphere. The 
 plaster should be the strongest and finest in quality, and 
 free from saline impurities. It should be well sifted to 
 free it from lumps or coarse grains, which otherwise 
 would appear as small specks of white in the midst of 
 the dark colors when the polishing is completed. Glue 
 water should be made in small quantities, or as much as 
 will suffice for the day, as it deteriorates if kept too long. 
 Glue tends to harden the plaster, and gives gloss to the 
 surface. Unfortunately it is also the cause of its sub- 
 sequent dullness and decay when exposed to moisture 
 and damp air, hence the necessity of using the best glue, 
 good and fresh glue water. If scagliola is required to be 
 done in situ on brick walls, the joints should be well 
 raked out and the walls well wetted. This gives a good 
 key, stops the excessive absorption, and partly prevents 
 the evil effects of saline matters, that are found in most 
 kinds of new bricks. These saline matters are the prin- 
 cipal cause of subsequent efflorescence which sometimes 
 appears on plastic surfaces, and is so unsightly and dis- 
 astrous to surface decorations. Saline matters are also 
 caused by acids, used in the manufacture of some ce- 
 ments. Saline is also found in mortars made with sea 
 water, or with unwashed sea sand. These impurities 
 can be avoided by carefully selecting, mixing, and work- 
 ing of the materials. Brick walls for scagliola should 
 be allowed to stand as long as possible, and wetted at in- 
 tervals. This allows more time for the saline to exude 
 and be washed off. The exudation may be hastened or 
 the salts absorbed and killed by brushing the walls with 
 ^a solutiQn of freshly slaked lime. This is allowed to stand 
 until dry, and then cleaned off by scrubbing with warm 
 water and a coarse broom. If space permits, a wall bat- 
 tened and lathed is the best preventive. Scagliola slabs, 
 
266 CEMENTS AND CONCRETES 
 
 screwed to plugs or battens, are protected from saline 
 and internal damp. 
 
 Iron columns to support overhead weights, and fixed 
 as the building proceeds, are often covered with scaglio- 
 la. If the work is done in situ, the iron core is sur- 
 rounded with a wood skeleton and strong laths, or paint- 
 ed wire lathing. The wood templates are cut, equal to 
 the lower and upper diameters of the columns, and one 
 fixed at the top and bottom of the shaft. The ground 
 work is then ruled fair with a diminished floating rule. 
 This gives a guide and equal thickness for the scag (the 
 trade abbreviation for scagliola stuff). 
 
 The floating coat is composed of the best and strong- 
 est plaster procurable, and gauged as stiff as possible 
 with sufficient strong size water, so that it will take from 
 twelve to twenty-four hours to set. The floating is gen- 
 erally brought out from the lath in one coat. A tenth 
 part of well-washed hair is sometimes mixed with the 
 gauged plaster, to give greater toughness and tenacity. 
 The surface must be carefully scratched with a singly- 
 pointed lath, to give a sound and regular key for the 
 scag, which is laid on in slices, and pressed and beaten 
 with a stiffish, square pointed gauging trowel, somewhat 
 like a margin trowel. The scag is laid about % inch 
 fuller than the outline, and when set, the surface is 
 worked down with a "toothed plane." This plane is 
 similar to that used by cabinetmakers for veneering pur- 
 poses. The irons are toothed in various degrees of fine- 
 ness, and set at an angle of 70 degrees. If the columns 
 are fluted, a half-pound plane is required for the flutes. 
 As the planing proceeds, the outline is tested at inter- 
 vals with a rule, as a mason does in using a straight- 
 edge when working mouldings. A planed or chisel-cut 
 surface shows up the grain and figure of the marble 
 
MISCELLANEOUS MATTERS 267 
 
 much better than if ruled. A rule is apt to work out or 
 otherwise spoil the figure of most marbles. The beating 
 on the slices may disturb the figure of the marble at the 
 outer surface, but if the scag is gauged stiff, the inner 
 portion will be intact, hence the advantage of planing. 
 To obtain greater cohesion between the scag and the 
 floating, the latter is brushed with soft gauged stuff just 
 before each piece of the former is laid. The scratching 
 is also filled up at the same time, so as to obtain the full 
 power of the key with the least amount of pressing on 
 and beating the scag slices in position. When the shaft 
 is planed, the wood colors are taken off; then the base 
 and necking moulding, which has been previously cast, 
 are screwed in position, using plaster (colored the same 
 as the ground of the marble) for the joints. When dry, 
 the whole is stoned and polished. Pilasters or other 
 surface work done in situ are executed by similar pro- 
 cesses. Cast and turned work should always be support- 
 ed by strong wooden, frames, formed with ribs, and cov- 
 ered with ^ inch to i^^h thick sawn laths. The 
 strength of the frames is regulated according to the posi- 
 tion and purpose of the intended work. For example, a 
 column with base placed on a square pedestal would not 
 require so strong framing as the pedestal which has to 
 support the column and base. Also being on the floor 
 level, it is more exposed to contact and pressure. Fram- 
 ing is also necessary for fixing purposes, and to allow 
 for the work being handled freely when being moved 
 from the work shop to the building, and when being 
 fixed. Small work may be made without framing. 
 Turned columns are framed in two different methods, 
 each way being for a special purpose. If it is an ^'in- 
 dependent column'', or in other words a complete col- 
 umn, not intended to surround a brick or iron core, the 
 
268 CEMENTS AND CONCRETES 
 
 frame is made lighter and thinner, and in such ways as 
 to admit the column to be cut either in two equal parts, 
 or with one-third out, or just as much as will allow the 
 larger part to pass over the iron core. Care must be 
 taken that the inner diameter of the skeleton frame is 
 greater than the diameter of the iron core. This is to 
 allow for fixing. The outer diameter of the frame is made 
 about 1 inch less than the finished outline of column, to 
 allow % inch for the core and ^ inch for the scag. The 
 two parts of the frame are fixed with wooden pegs (not 
 nails), so that they may be sawn when the column is cut 
 into halves. This is not done until the column is pol- 
 ished and ready for fixing. The parts are best separated 
 by cutting with a thin and fine-toothed saw. The thin- 
 ner the cut the better the joint. The two parts are 
 fixed on the iron core with brass screws or clamps, from 
 3 to 4 feet apart, and the joints made good with colored 
 plaster as before. Sometimes a zigzag joint is made, the 
 one side fitting the other, to give the marble or figure a 
 more regular and natural appearance. The joints are 
 then stopped with various tints, these being the same 
 gauge as used for the face. 
 
 Sometimes the framing is made longer than the shaft, 
 so as to project at each end. These projecting parts are 
 used as fixing points for screws, and binding round with 
 hoop-iron before the plinth and cap are fixed. These 
 parts project the edges of the work while being moved 
 and fixed. Considerable skill and patience is required 
 to make a strong joint, well polished, and imperceptiKe 
 to the eye. The frames are made with solid ends, with 
 a square hole in each to fit the spindle. The solid ends 
 are cut out of inch deal, and are used to keep the skele- 
 ton firm and in a central position when the spindle is 
 turning on its bearings. One of the ends is fixed to 
 
MISCELLANEOUS MATTERS 269 
 
 flange of the spindle with screws. If a case column is 
 being made, the solid ends are taken off before the col- 
 umn is cut ; but they form permanent parts of the fram- 
 ing for an independent column. The mould is fixed at 
 one side, and level with the centre of the spindle, which 
 is the centre of the column's diameter. Care must be 
 taken that the profile of the mould plate to the centre 
 of the spindle is one-half of the required diameter at 
 each end of the shaft. 
 
 Vases are generally made without wood framing. They 
 are turned on a spindle with a plaster core screwed to the 
 flange in the form of a parabola, to give the form of the 
 hollow inside. On the core a coat of scag is laid and al- 
 lowed to set. This is scratched to give a key for the 
 coarse plaster w^hich forms the body of the vase. This 
 is formed to the desired outer profile by means of a 
 mould fixed on the outside, and muffled to allow for a 
 thickness of outside scag. When the core is run, the 
 muffle is taken off, and the scag laid, keeping it about % 
 inch thicker than the true profile, to allow for turning 
 and stoning. When the scag is set, it is turned, and 
 then the vase is taken off the spindle and plaster core. 
 The spindle hole is used as a key for a slate or iron dowel 
 for fixing the vase on to the square plinth. The vase is 
 then polished. Cheap work is usually run or turned 
 with a mould. This is done to save turning with chisels, 
 but it spoils the true figure of most marbles. 
 
 A more recent way of imitating marbles is known by 
 the name of Marezzo, which does not require so much 
 polishing, being made on plate glass or other smooth 
 surface. Keen's superfine plaster is used. The mode 
 of making Marezzo is described later on. Specimens of 
 the real marbles^ to give the color and form of veining, 
 
270 CEMENTS AND CONCRETES 
 
 spots, and figures, will be of great service to the be- 
 ginner. 
 
 Mixing. — Mixing the colors is an important part of 
 scagliola manufacture, and the following colors, mixing 
 and mode of using, will serve as an index for the imi- 
 tating of any other marble that is not detailed. Fine 
 plaster (not cement) is used for making the best class 
 of scagliola, gauged with sized water, which is made by 
 dissolving 1 lb. of best glue with 7 quarts of water. (This 
 is known in the trade as strong water".) The stuff, 
 when gauged will take about six hours to set. All mix- 
 ing is done on a clean marble or slate slab. One of the 
 principal arts is the mixing, but there are no two men 
 who mix exactly alike, and it is largely a matter of ex- 
 perience. The chopping or cutting into slices with a 
 knife is another important point in the mixing, apart 
 of course from the special colors. Where there are two 
 shades of one color in any given work, the cutting does 
 not affect their original shade. No dry color is used, 
 only ground water-colors. The beginner had better ex- 
 periment with a small sample of ^^Penzatti" or Pen- 
 zance marble. With one gill of size w^ater, gauge plaster 
 middling stiff, then mix thoroughly with the gauged 
 plaster a little red. Do the same Avith a little black. 
 (See quantities below.) Blend this stuff properly by 
 working it on the bench with the hands (not tools), then 
 roll it out, and cut it into slices about one inch thick. 
 Take up these slices, and part them with the fingers 
 about the size of a walnut, and put them aside, a little 
 distance apart, on a bench. 
 
 The veining in this instance is white. Over these little 
 lumps scatter half a handful of crumbs, made by re- 
 serving a little of the gauged plaster, and making it 
 crumbly with dry plaster, mixing with it a few small 
 
MISCELLANEOUS MATTERS 271 
 
 bits of alabaster or marble. Then gauge a little plaster 
 in a basin, with a tooth brush, about 2 inches wide, dip 
 into this gauged plaster, and smudge the little lumps all 
 over with it. Knock these lumps together into a big one, 
 and chop the big lump three times. (This chopping 
 means cutting with a knife into slices once, and knock- 
 ing up again; cutting with a knife a second time, and 
 knocking up again ; and then cutting with a knife a third 
 time, when it is finished.) This lump is then ready to 
 be cut into slices, and applied to any purpose required; 
 but in this case, being wanted for a specimen, it is cut 
 into slices about % inch thick, and laid close together 
 flat on a sheet of paper, and allowed to remain until set. 
 It is then planed, and when dry polished. This opera- 
 tion is an embodiment of the principle of ''scag" mix- 
 ing nearly from beginning to end, only submitting one 
 color for another for the various marbles. The mixing 
 is generally known as plain and rich, and may be 
 described thus: Take a Sienna pedestal, for instance. 
 Two shades of sienna, plain mixing; one or two shades 
 of dark with veining, rich mixing, both done on the same 
 principle as Penzatti. They are cut into slices and laid 
 on alternately. All veining of any color is done as 
 described above, only modified by the consideration that 
 if strong veining is wanted the stuff must be stiffish, and 
 for fine veining it must be slightly softer. Various-sized 
 measures for the water and scales for weighing the color 
 should be used. Pats of each gauge should be set aside 
 as test pats to determine when the main portion of stuff 
 is set. It is advisable to number the pats for future 
 reference as to quantity of colors, time of setting, and 
 tints when dry. The various colors and tints are gauged 
 and chopped as previously described, and according to 
 the marble required. The core being laid on the skele- 
 
272 CEMENTS AND CONCRETES 
 
 ton, and left in a keyed and rough state until dry and 
 expansion ceased, it is ready when set for the scag. The 
 core is now damped and well brushed with the white or 
 other vein that has to be made. The veining is gauged 
 thin, and being brushed and laid in the core, will tend to 
 make the slices adhere better, and fill up the interstices 
 caused by the jagged edges of the cut slices. The slices 
 are then taken and pressed firmly onto the core, arrang- 
 ing in proportion to the figure of the marble. To render 
 the work more dense^ beat- it with a fiat-faced mallet 
 and a large gauging trowel with a square end. Try the 
 work with a rule to see if the surface is fair. The 
 rough surface should not be less than % inch thicker 
 than the true line of the work, to allow for planing and 
 stoning. When required, pieces of alabaster are inserted 
 before the stuff is set. Metallic ores are used in 
 some marbles, also pieces of granite and real 
 marble. When the scag is laid^ the work is left until 
 set and dry. It is then planed stopped, stoned and 
 polished. Columns and circular work are turned on a 
 lathe, and the rough surface reduced to the true profile 
 with long chisels similar to those for turning wood or 
 other materials. This should not be attempted until the 
 materials are thoroughly set. 
 
 Colors mid Quantities. — The following are the colors 
 and quantities used for various marbles. The propor- 
 tions of strong water, which is made varies, the due 
 quantity should be tested by gauging small pats of 
 plaster to ascertain the time of setting. As the tints of 
 real marble vary in some species, the mixing must to 
 some extent be left to the ingenuity of the workman. 
 With a little practice and perseverance, a careful and 
 observant man will soon succeed in getting the required 
 tints. 
 
MISCELLANEOUS MATTERS 
 
 273 
 
 Penzance Marble. — 10 oz. of light purple brown to 1 
 pint. Veining (plain mixing), 2 oz. black to 1 gill; vein- 
 ing (rich mixing) 5 oz. black to 1/2 pint; veining (rich 
 mixing), 1 oz. black to I/2 gill. All liquid measurements 
 refer to strong water. 
 
 Egyptian Green. — 5 oz. black to 1 pint. Veining, i/^ oz. 
 green to % pint light shade ; veining, i/4 oz. green to I/2 
 gill. White the same, black chopped three times ; a few 
 black spots same as brown Beige. 
 
 Brown Beige. — Four shades — 1 light purple brown 
 (indigo) ; 2 middle shades (blue black) ; 1 very dark 
 shade (vegetable black). Veining, burnt sienna with red 
 alabaster spots — 4 oz. (light shade) to ^ pint; 4 oz. 
 (middle) to % pint; 4 oz. (very dark) to i/^ pint; 
 Y2 oz. burnt sienna to pint ; 1/4 oz. black to i/4 pint ; 
 ^2 piiit for the grey with crumbs, and red alabaster 
 spots'. 
 
 Dark Porphyry. — Color, light purple brown, with 
 black, and a little ultramarine, blue spots, black, ver- 
 milion grey, and a little red. 
 
 Green Genoa. — 214 oz. green to i/^ pint (rich mix- 
 ing.) ; 5 OZ. black to 1 pint. Veining, l^ oz. green to 14 
 pint. White veining the same, with alabaster spots, and 
 black. 
 
 Rouge Boyale. — Color, light purple brown, with a little 
 sienna, and umber, with ultramarine, blue or blue black. 
 Vert-Vert. — 1/4 oz. green to I/2 pint; dark green with 
 sienna; dry green plaster. 
 
 Devonshire Bed Marble. — All sienna work. Light 
 mixing — 1 shade grey; 1 shade lemon chrome; 1 shade 
 light purple brown; 1 shade flesh color; veining burnt 
 sienna. Dark mixing.\ — 1 shade light purple brown, 
 with indigo blue in it; 1 shade dark purple brown; 1 
 shade middling purple brown; 1 shade grey; 1 shade 
 
274 
 
 CEMENTS AND CONCRETES 
 
 lemon chrome. Veining, burnt sienna, with small ala- 
 baster spots. 
 
 Sienna Mixing, — 5 oz. sienna to I/2 pint, dark shade; 
 3 oz. sienna to I/2 pint, middle shade; 2 oz. sienna to 
 1/2 pint, light shade. 
 
 Griotte Marhle. — 10 oz. of light purple brown to 1 
 pint 5 oz. of dark purple brown to % pint, with ala- 
 baster spots. Ground with red veins, and small spots. 
 
 Spanish Buff. — Burnt sienna, 2 shades, with large ala- 
 baster spots. Veining, white and blue black, with small 
 alabaster spots. Ground with red veins, and blue spots. 
 
 Light Verd Antique. — 2I/2 oz. green to Yo pint; 
 iy2 oz. black to 1 gill ; I/2 gill black to 1 gill grey shade. 
 
 Dark Verd Antique. — Green spots cut; grey spots cut ; 
 black spots with green and grey. Veining 2^/2 oz. green 
 to 1/2 pint (rich mixing) ; 2% oz. dark green to I/2 pint 
 (rich mixing) ; 1/4 oz. black to I/2 pint (rich mixing). 
 
 Plain mixing, same as above, with small alabaster 
 spots, and small black spots. 
 
 Black and Gold. — 5 oz. of black to 1 pint. Veining, 
 
 2 shades dark sienna to I/2 pint (rich mixing) ; 2 shades 
 light to 1/^ pint (rich mixing) ; 2 parts light and grey, 
 with alabaster spots, and crumbs. Veining must be stiff ; 
 
 3 oz. of black to 1 gill. 
 
 Walnut. — 2 parts burnt umber; 1 part rose pink. 
 
 Ve7^ta Alps Marhle. — 5 oz. black to 1 pint. Veining, 
 114 oz. of green to li/4 gills; 14 oz. green to 1/2 gill, with 
 black crumbs chopped three times for the ground. 
 
 Rosse De La Vantz Marble. — Rich mixing with indi- 
 go blue — 1 shade light purple brown ; 1 shade dark pur- 
 ple brown; 1 shade Venetian red. Veining, black for 
 the ground, and white and green veining for the mixing, 
 with alabaster spots and crumbs. 
 
MISCELLANEOUS MATTERS 
 
 275 
 
 Polishing White Scagliola. — White scagliola is often 
 made with superfine Keen's cement. A small portion of 
 mineral green or ultramarine blue is added to improve 
 and indurate the white color. White work requires spe- 
 cial care to prevent discoloration or specks. When the 
 work is left for drying purposes, or at the end of the day, 
 it should be covered up with clean cotton cloths to pre- 
 vent the ingress of dust, smoke or being touched with 
 dirty hands. The tools should be bright and clean. Steel 
 tools should be as sparingly used as possible. When the 
 cement has thoroughly set and the work is hard, it is 
 rubbed down with pumice-stone, or finely grained grit- 
 stone, by the aid of a sponge and clean water, rubbing 
 lightly and evenly until the surface is perfectly true. It 
 is then stoned with snake-water (Water of Ayr), using 
 the sponge freely and the water sparingly until all the 
 scratches disappear. Afterwards well sponge the sur- 
 face until free from glue and moisture. It is now ready 
 for the first stopping. Stopping is an important part of 
 the polishing process, and should be carefully and well 
 done, to ensure a good, sound, and durable polish. 
 
 First gauge a sufficient quantity of cement and clean 
 water in a clean earthenware gauge-pot. The gauged 
 stuff should be about the consistency of thick cream. It 
 is well dubbed in, and brushed into and over the surface, 
 taking care that no holes or blubs are left. When the 
 stuff on the face gets a little stiff, scrape off the super- 
 fluous stopping with a hard-wood scraper having a sharp 
 edge. Then repeat the brushing (but not the dubbing) 
 with the soft gauged stuff, and scraping two or three 
 times, or until the surface is solid and sound. The work 
 is now left until the cement is perfectly set. It is then 
 stoned again for the third time with a piece of fine snake- 
 stone, and stopped as before, with the exception that the 
 
276 CEMENTS AND CONCRETES 
 
 superfine stopping is not scraped off, but wiped off with 
 soft clean rags. The work is left until the cement is set 
 and the surface dry. It is then polished with putty 
 powder (oxide of tin), which is rubbed over the surface 
 with soft clean white rags, damped with clean water. In 
 polishing mouldings, the stone must be cut or filed to fit 
 each separate member of the moulding. 
 
 Polishing Scagliola. — The polishing of scagliola is 
 slightly different. It is rubbed down with a soft seconds 
 (marble grit) or gritty stone, using the sponge and water 
 freely until the surface is true. The glut and glue are 
 cleaned off with a brush and sponge, using plenty of 
 water, until the pores are free from grit. The moisture 
 is sponged off, and the work left until sufficiently dry. 
 It is then stopped in the same manner as white work, but 
 using stiff stopping for large holes and steel scrapers in- 
 stead of wood. The stopping is made with the same 
 kind of plaster, size water, and color as was used for 
 the ground color of the marble that is being imitated. 
 The stopping and stoning is repeated as before, and it is 
 finally polished with putty powder, using pUre linseed oil 
 instead of water. The repeated operations of stopping 
 and stoning must not be proceeded with until the 
 previous stopping is perfectly set, and the work dry. A 
 small portion of spirits of turpentine is sometimes added 
 to the gauged colored stuff to facilitate the drying. The 
 work between each combined stopping and stoning will 
 take from one to five days to dry, according to the size 
 and thickness of the work and the state of the atmos- 
 phere. Never dry the work by heat. The thorough dry- 
 ness and hardness of the work are most essential be- 
 fore proceeding to polish with the putty powder and lin- 
 seed oil, because any contained damp will work out and 
 spoil the polish. Work not perfectly dry may take a 
 
MISCELLANEOUS MATTERS 277 
 
 high polish, but it will soon go off when the damp comes 
 through. Columns or large hollow work are not so liable 
 to be affected by the damp, as it may escape through the 
 back; but there must be some opening or ventilation to 
 allow it to finally escape. 
 
 If the polishing is well and carefully done, the polish 
 produced on scaglioia will equal, if not surpass, that on 
 real marble. Tripoli polishing stone, sometimes called 
 alalia, is a kind of chalk of a yellowish-grey color. Water 
 of Ayr stone is also used for polishing. In large work 
 a rubber of felt dipped in putty powder may be used. 
 Salad oil is sometimes used for finishing. Linseed oil 
 makes the hardest finish, and dries quicker. 
 
 MarezzO'. — Marezzo artificial marble manufactured 
 from plaster or Keen's cement and mineral coloring mat- 
 ter is made in wood or plaster moulds for moulded work, 
 and on slate or glass benches if in slabs. If thick plate 
 glass is used, the worker has the advantage of being able 
 to look through it to see if the figure of the work re- 
 quires altering. Glass also has the advantage of leaving 
 a smoother and more polished face. All wood and 
 plaster moulds should be got up with a good face, and 
 properly seasoned, to save stoning and polishing the face 
 of the work. Keen 's cement may be used advantageous- 
 ly in making Marezzo, especially for chimney pieces, or 
 other works required for exposed positions. Keen's 
 cement for Marezzo should be of the highest class. If 
 the cement is not of the best, it will effloresce, rendering 
 the work of polishing difficult, if not spoiling it alto- 
 gether., Keen's cement requires no size water, but in 
 gauging either Keen's or plaster, no more should be 
 gauged than can be conveniently used. The quantities 
 of colors. Keen's cement, plaster, and size water should 
 be measured and gauged pats kept for future reference. 
 
278 CEMENTS AND CONCRETES 
 
 All gauge-pots snould be of earthenware, as they are 
 more easily cleaned out, and do not rust, as is the case 
 with metal pots. All the tools should be kept bright and 
 clean, as when working scagliola. 
 
 Marezzo is made in the reverse way to scagliola, as the 
 face or marble is put in the mould first, and the core or 
 backing put on afterwards. 
 
 All the mineral colors should be of good quality, in 
 fine powder, and ground in water, known as ' ' pulp. ' ' A 
 number of basins should be handy, and there should be 
 a supply of twist silk in skeins varying in diameter from 
 % to % of an inch, and cut into lengths of 14 to 18 
 inches. For common work, good long flax fibre may be 
 used. Canvas is also required. One end of the silk or 
 fibre skein must be knotted. ^ These are known as ' ' drop 
 threads. ' ' 
 
 After the moulds are made, seasoned, and oiled, the 
 young hand may begin by trying to make some easy 
 marble, for a slab or chimney-piece. Gauge Keen's extra 
 superfine cement or superfine plaster, in a large basin 
 labelled No. 1, well mixing it until about the consistency 
 of cream. This is pure white. Now pour a small quan- 
 tity of this white plup into two small gauge-pots, Nos. 
 3 and 4. Pour a third of what remains in the No. 1 
 pot into another gauge pot. No. 2. Take some black- 
 colored pulp, and make No. 1 a blackish-grey. Color 
 in the same way No 2. only very much blacker than 
 No. 1. No. 3 is now slightly tinted with pulp from No. 
 1. This leaves No. 4 pure white. Then take a skein of 
 twist (or threads), dip into No. 4, the pure white, and 
 well charge it by stirring it about with the fingers ; take 
 out the threads, taking each end between the thumb and 
 forefinger of each hand, and with the remaining fingers 
 of each hand separate the threads, allowing plenty of 
 
MISCELLANEOUS MATTERS 
 
 279 
 
 *^swag/' and strike this into the face of the mould, mak- 
 ing each stroke at different angles, recharging the 
 threads when necessary. Repeat this process with pulp 
 from No. 3, but in a lesser quantity; then dip your 
 finger ends into No. 2, and fling drops about the size of 
 large peas all over the veining. These drops must be 
 thrown on with considerable force, so as to cut into the 
 veins as much as possible. Dip the fingers into No. 
 1, and throw on No. 2, using alternately from each gauge- 
 pot until you get a uniform thickness of surface (scag), 
 about % inch in thickness. Now run a trowel over this 
 to lay down any ridges. Cover the work with a piece 
 of canvas, laying it evenly, smoothly, and without 
 wrinkles. Be careful to put the canvas in the proper 
 place, as moving it would spoil the lines of the veining; 
 then spread a quantity of dry coarse Keen's lightly over 
 the entire surface. This will absorb any superfluous 
 moisture through the canvas. After the canvas and 
 coarse Keen's have lain from ten to tv/enty minutes, or 
 according to the stiffness of the gauge of the marble, the 
 canvas and coarse cement/ are easily lifted off. Should 
 any portion of the face of the scag leave the mould, and 
 adhere to the canvas, it is taken off and put back in 
 its place in the mould. The whole surface is now 
 trowelled to render it dense and hard. The moisture 
 should be sufficiently absorbed, or the trowelling may 
 spoil the figure. The proper absorption of the moisture 
 by the dry cement through the canvas, and well trowel- 
 ling, are most essential to good work, ensuring hardness 
 and density. 
 
 The core or backing is now made by using the coarse 
 Keen's previously used for absorbing the moisture from 
 the face, gauging it with some fresh coarse Keen's as 
 stiff as possible. This is laid on as thick as required. If 
 
280 CEMENTS AND CONCRETES 
 
 the face of the scag be very dry, spread a thin coarse 
 gauged Keen's, so as to give a perfect cohesion between 
 the marble and the backing. The flat surface of the 
 backing" should always be ruled or floated straight with 
 a uniform thickness, so as to give a true bed for the cast 
 when it is taken out of the mould, and, laid on a bench 
 ready for stoning, stopping, and polishing. This can 
 be done as soon as it is thoroughly set and hard, and in 
 the same manner as scagliola. 
 
 Marbles having; long stringy veins require a different 
 method of putting in the veins. Take the skeins, or - 
 ^ threads, " by the knot with one hand, and thoroughly 
 saturate them with the veining mixture, and run the 
 finger and thumb of the other hand down the threads ' 
 to clear them of any excess of veining color with which 
 they may be charged. Then give the end not knotted to 
 your partner, holding the knot in your left hand. Pull 
 the threads asunder, so as to take the form of the veins 
 of the marble you are copying, then lay them in the 
 mould, leaving the knots hanging over the edge of the 
 mould, or at least visible, to facilitate their removal 
 when required. The threads should be arranged on the 
 mould so as to take the form of the veining. The other 
 colored materials are then thrown upon the thread veins, 
 which quickly absorb the coloring matter from them; 
 care being taken that the various colors are thrown or 
 dropped from the finger tips, to form the figure of the 
 body of the marble that is being copied. When the 
 mould is sufficiently and properly covered with the 
 marbling, take hold of the knots and withdraw the 
 threads. These should be cleaned by passing down the 
 finger and thumb for future use, saving the superfluous - 
 stuff for filling up any holes in the marbling. The 
 absorption of the use of canvas and dry coarse Keen's, 
 
MISCELLANEOUS MATTERS 281 
 
 -and the filling in of the backing or core, is then 
 proceeded with as before described. 
 
 Granites, porphyries, etc., are made in a different 
 manner. For porphyries with white and black specks, 
 make a slab of white Keen's about % inch thick, and 
 another in black, the same thickness. When they are 
 set and hard, chop them into small pieces, then run them 
 through a sieve, having a mesh to let through the pieces 
 of the required size only. The pieces retained in the 
 sieve can be broken and sieved again. The whole is 
 now sieved again through a smaller mesh, which re- 
 tains only the size wanted. The refuse can be used for 
 small work or backing up. AVhen the gauged stuff for 
 the facing is mixed of the required tint (a reddish- 
 brown), damp the black and white specks with the 
 gauged color by means of a trowel and rolling, care 
 being taken not to break the edges and faces of the 
 black and white specks. When it is well mixed, lay it 
 onto the face of the mould about 3-16 inch thick, press- 
 ing it as firmly and evenly as possible. Then absorb the 
 moisture by means of canvas and dry coarse Keen's, 
 trowel it well to give density, and fill in the backing or 
 core as before. For Rouge Royale, " ^^Verd Antique," 
 &c., requiring large white patches of irregular size, the 
 sieving can be dispensed with. The white pieces are 
 broken haphazard, and pieces of alabaster can also be 
 inserted in these, and many other marbles, due regard 
 being given to the size and quantity, so as not to produce 
 an unnatural effect. The remainder of the figure is 
 formed with the ^'drop threads," and the other colors 
 being thrown on. 
 
 From this description of Marezzo, the workman will 
 understand that in the case of marbles classed as ^ ^Brec- 
 cias, such as ^' Rouge Royale, " Black and Gold," &c., 
 
282 CEMENTS AND CONCRETES 
 
 having patches and rough jagged veins in them, he must 
 have flat pieces of the required color previously made 
 and broken up, or alabaster, as the case may be inserted 
 into them, and the veining done with the ''drop threads'^ 
 and that fine or long veining threads are not required; 
 that unicolored marbles require no veining threads ; that 
 the long veined marbles require the long threads, and in 
 some cases the ''drop threads'' as well, and that granites, 
 porphyries, &c., require no threads; that black is diffi- 
 cult to make owing to the pure white cement requiring so 
 much color; and finally, that in all cases, whether Ma- 
 rezzo or scagliola, the polishing is done in a similar man- 
 ner, whether using plaster. or Keen's cement. 
 
 The details given must be carefully followed to pro- 
 duce work artistic in figure and appearance. The direc- 
 tions for making "St. Ann's" so far as manipulation is 
 concerned, apply to all others. A little patience, prac- 
 tice, and perseverance will soon give confidence and ex- 
 pertness in producing sound scagliola and Marezzo. 
 
 Granite Finish. — Granite is a peculiar finishing coat of 
 plaster which is sometimes used in this country to imi- 
 tate granite. For granite finish, first render the walls 
 with hydraulic lime, and when nearly dry lay with a thin 
 coat of the same material but colored light brown. Then 
 while this coat is still moist, splash the surface lightly 
 with white stuff, then with black stuff, using only half 
 as much as used for the white stuff. The red stuff is 
 best applied by dotting the surface with a small brush 
 charged with the colored stuff. After these colored lime 
 stuffs are firm, but not set, the surface is carefully trow- 
 elled, using the minimum of water so as not to mix the 
 various colored stuffs. The surface is sometimes left in a 
 rough state, or as left when splashed. After the surface 
 
MISCELLANEOUS MATTERS 283 
 
 is firm, it is set out and jointed to represent blocks of 
 graite. 
 
 Granite Plastering, — Granite plastering is a method, 
 introduced by the author, to imitate granite. This mode 
 of imitating granite is based on the scagliola process. It 
 is also somewhat similar to the granite finish, and gives 
 better and more reliable results. 
 
 The method of executing granite plaster work is as 
 follows : First select the most suitable lime or cement 
 for the situation, such as Portland cement or hydraulic 
 lime for exterior work, and Parian or other white cement 
 for interior work. Having decided on the material, 
 gauge three different colored batches, one white, one red, 
 and one black, taking care that the stuff is gauged stiff 
 and expeditiously so as to obtain a hard substance. The 
 material is colored to the desired shades, as described 
 for scagliola or colored stuccos. When gauged the stuffs 
 are laid separately on a bench and rolled until about 
 3-16 inch thick, and when nearly set they are cut into 
 small irregular cubes and allowed to set and harden. The 
 wall is then floated, ruled fair, and the surface keyed, 
 and when set it is laid with a thin bedding coat of simi- 
 lar stuff used for the floating, but colored light brown. 
 The colored cubes are then mixed together in due propor- 
 tions, and gauged with a portion of the light brown col- 
 ored stuff and laid on the thin coat while it is soft. The 
 whole is then firmly pressed with a hand-float until a 
 close, compact, and straight surface is obtained, taking 
 care when pressing the stuff not to break the cubes. 
 After the stuff is set and perfectly dry and hard, the 
 surface is rubbed down and polished, as described for 
 scagliola or for marble plaster. The bedding coat should 
 be sufficiently thick to receive the colored cubes, other- 
 wise the larger cubes will project at parts, and cause 
 
284 
 
 CEMENTS AND CONCRETES 
 
 extra labor in making a uniform and straight surface. 
 Unless the cubes are fairly level when pressed, the sur- 
 face will have a spotty appearance, besides being more 
 difficult to polish. Where expense or time is a consid- 
 eration, a striking appearance is obtained at less cost 
 than polished work, by simply finishing the surface with 
 a cross-grained hand-float, and a semi-polished surface is 
 obtained by trowelling, or by scraping the surface with 
 a joint-rule. Grey or light-colored granites are imitated 
 by altering the colors of the cubes and the bedding coat 
 as desired. Bold and striking effects on wall surfaces 
 can be obtained by a combination of different colored 
 granites, laid out in bands and borders. The effect can 
 be increased by the introduction of borders in sgraffito^ 
 with the bands in granite plaster. 
 
PART II 
 
 CEMENTS AND CONCEETES, AND HOW TO USE 
 
 THEM. 
 
 It is not necessary to the workman that he should ex- 
 pend a long period of his valnable time in reading up 
 the history of cements and concretes, nevertheless it is 
 proper he should be acquainted with the outlines of the 
 origin, growth, and development of cements, concretes 
 and their uses, and to this end the following brief his- 
 torical summary is presented, sufficient to give the work- 
 man a fair idea of the beginning and growth of the use 
 of cements and concretes : 
 
 The word concrete is of Latin origin, and signifies a 
 mass of materials bound or held together by a cementing 
 matrix. The Romans used concrete B. C. 500. They 
 made good use of lime concrete both in the construction 
 of buildings and roadways. ''Eoads," says Gibbon, 
 ^'were the most important element in the civilization 
 of ancient Rome; and the cost of the Appian Way was 
 such as to entitle it to the proud designation of 'Re- 
 gina Viarum' (the Queen of Roads)." The Appian 
 (the oldest of the Roman highways) was commenced by 
 Appius Claudius Gains, when he was censor, about three 
 centuries before the birth of Ghrist. It extended from 
 Rome to Gapua, whence it was consequently carried on 
 to Tarentum and Brundusium. Antonio Nibby, an 
 archaeologist of the highest authority, states that the 
 Appian Way had an admirable substructure, with lime 
 concrete materials superimposed, and large hexagonal 
 
 285 
 
286 CEMENTS AND CONCRETES 
 
 blocks of stone laid on the top of all. The Eomans built 
 concrete aqueducts, often several miles long, to convey 
 water to the cities. The palace of Sallust, the historian, 
 was built about B. C. 50, and was frequently used as a 
 residence by most of the emperors until as late as the 
 fourth century. It was partly burnt by Alaric in the 
 year 410. This once magnificent edifice was erected on 
 a strange site, partly in the valley at the foot of the 
 Quirinal Hill, and partly on the top of the hill. The 
 latter portion of the palace, which was of great extent, 
 has been almost wholly destroyed by the builders of the 
 modern boulevard. The walls, which were thick and 
 high, were most valuable examples of the Roman use of 
 concrete, unfaced by brick or stone. There is still visi- 
 ble evidence, in the form of impressions left on those 
 walls, which clearly demonstrates their method of cast- 
 ing walls in situ by means of wood framing. Rows of 
 timber uprights, about 10 feet high, 6 inches wide, and 
 3 inches thick, were fixed along both faces of the in- 
 tended wall. Boards about 10 inches wide and II/2 
 inches thick, in suitable lengths, were then nailed hori- 
 zontally along the uprights, thus forming two parallel 
 wooden walls, into which the concrete was laid and 
 rammed until the space between the boards was filled 
 to the top. When the concrete had set, the wood fram- 
 ing was removed, and refixed at the top of the concrete, 
 the whole process being repeated until the wall was 
 raised to the required height. This concrete was far 
 more durable than brick or stone. The jerry-builders of 
 the modern Rome had no difficulty in pulling down the 
 stone wall of Servius, but the concrete walls required the 
 use of dynamite to complete their destruction. After 
 withstanding the wear and tear of many centuries, and 
 the repeated onslaughts of the Goths and Vandals, it was 
 
HOW TO USE THEM 
 
 287 
 
 left to the nineteenth-century speculative builder to de- 
 stroy those interesting remains. 
 
 The use of concrete for floors and roofs is of great an- 
 tiquity. It was employed for this purpose by the Ro- 
 mans in the time of Julius Caesar. Professor Middleton, 
 in his first book^ Ancient Eome," states that the whole 
 of the upper floor of the Antrium Vesta is formed of a 
 great slab of concrete^ 14 inches thick, and about 20 feet 
 in span, merely supported by its edges on travertine cor- 
 bels, and having no intermediate supports. In his sec- 
 ond book, ^ ' The Remains of Ancient Rome, ' ' Professor 
 Middleton mentions that the Romans used concrete for 
 the construction of the Pantheon, which was erected 
 about the time of Christ. A curious and apparently un- 
 accountable feature as regards practical purposes is that 
 the concrete is faced with bricks, which were faced again 
 either with stucco or (in special cases) with marble 
 veneer. The Professor gives a sketch showing the ex- 
 terior facing and the section of a wall of this kind, the 
 entire mass being composed of concrete, except a facing 
 of thin bricks, triangular in plan, with the points in- 
 wards. As the author observes, these bricks could not 
 possibly be intended as a matrix for concrete, as it would 
 not have withstood the pressure of the latter while in a 
 wet state. It must therefore have been necessary to re- 
 tain the brick and the concrete with an external tim^ 
 ber framing, as in the case of unfaced concrete. There 
 could be no gain of strength or other benefit to compen- 
 sate for the time expended setting the brick skin. The 
 dome of the Pantheon is 142 feet in diameter and 143 
 feet high. This is also formed with brick- faced concrete. 
 It has often been described and even drawn by various 
 authors as essentially a brick dome. Professor Middle- 
 ton remarks there must have been very elaborate con- 
 
288 CEMENTS AND CONCRETES 
 
 struction of centring for this and other massive concrete 
 vaults. He states they employed a method, which has 
 become common of late, to avoid the necessity of build- 
 ing up the centring from the ground. They set back 
 the springing of the arch from the face of the pier, so 
 as to leave a ledge from which the centring was built- 
 the line of the pier being afterwards carried up until it 
 met the intrados of the arch, leaving it a segmental one. 
 The Professor also found signs of timber framing for 
 walls in the remains of the Golden House of Nero, un- 
 der the Thermae of Titus, where, he says, ''the chan- 
 nels formed by the upright posts are clearly visible. 
 These upright grooves on the face of the wall are about 
 6 inches wide by 4 inches deep, and they are afterwards 
 filled up by the insertion of little rectangular bricks, so 
 as to make a smooth unbroken surface for the plaster- 
 ing. This method is difficult to understand. Accord- 
 ing to the present practice, the supports should be fixed 
 outside the line of wall surface and leave no space to 
 fill in afterwards. He also mentions a striking example 
 of the tenacity of good concrete in the Thermae of Cara- 
 calla, at a part where a brick-faced concrete wall origin- 
 ally rested on a marble entablature supported by two 
 granite columns. ''In the sixteenth century," he says, 
 ' ' the columns and the marble architrave above them w^ere 
 removed for use in other buildings, and yet the wall 
 above remains, hanging like a curtain from the concrete 
 wall overhead. This proves that the Romans bestowed 
 as much thought and care on the materials and their 
 composition as they did on their construction. Profes- 
 sor Middleton notes that the larger pieces of aggregate in 
 the concrete, which are not close together, are so evenly 
 spaced apart as to lead to the conclusion that they must 
 have been put in by hand, piece by piece. 
 
HOW TO USE THEM 
 
 289 
 
 Dr. Le Plongeon, during his explorations in Peru, 
 found many remains of mud concrete walls. Although, 
 they were built many centuries ago, they have proved 
 sufficiently durable to exist until to-day. The materials 
 were placed between two rows of boards, and well beat- 
 en, and the exteriors were sometimes decorated with plas- 
 ter work. Thus it appears that the Peruvian builders of 
 the period of the Incas anticipated by centuries the 
 method (but not the material) of our modern concrete 
 buildings. Le Plongeon's researches conclusively estab- 
 lish the fact that these Indians were masters of concrete 
 building and plastering. The walls of the fortress of 
 Ciudad Rodrigo in Spain are built of concrete. There 
 are over twelve miles of arches and tunnels constructed 
 with concrete in the Varone Aqueduct, which supplies 
 Paris with water. One of the arches over the Orleans 
 Road, in the Forest of Fontainebleau, has a span of 125 
 feet without a joint, the arches and the water-pipe or 
 tunnel being entirely composed of beton, made with 
 Portland cement, hydraulic lime, and the sand found on 
 the spot. Concrete blocks weighing over 20 tons were 
 used in the construction of the Suez Canal, 3,000,000 
 tons of these blocks being required at Port Said alone. 
 Besides the unquestionable durability of concrete, it also 
 possesses fire-resisting and w^aterproof powers of the 
 highest degree. Constructional works formed with con- 
 crete carefully made and applied may be considered ab- 
 solutely fire-resisting and damp proof; in fact, in these 
 respects concrete has long since passed the experimental 
 period, inasmuch as numerous tests, under the most try- 
 ing and adverse circumstances, attest the superiority of 
 this material for sanitary and durable work. 
 
 The best concrete in France is that made under Coign- 
 et^s system of ''beton agglomere,'' and has been used 
 
290 
 
 CEMENTS AND CONCRETES 
 
 with great success in the construction of various large 
 and important works. In Paris many miles of the sew- 
 ers have been formed of this material, and a church in 
 the Gothic style, from the foundations to the top of the 
 steeple (which is 136 feet high) is entirely formed of 
 beton. The work was prosecuted without cessation for 
 two years, and was exposed to rain and frost, but has not 
 suffered in the slightest way from the extremes of tem- 
 perature. The strength of this material for constructive 
 work may be judged by the thickness, or rather want of 
 thickness, in the construction of a house, six stories high, 
 ^ having a Mansard roof — cellar, 19 inches, first story, 15 
 inches; second story, 13 inches, and diminishing 1 inch 
 every successive story, so that the sixth story was 9 
 inches. The cellars have a middle wall from back to 
 front, from which spring flat arches having a rise of one- 
 tenth of the span, the crown being 5 inches thick, and 
 at the springing 9 inches, which formed strong damp- 
 proof and fireproof cellars. There are many houses in 
 Paris, and this country, constructed of this material. It 
 has been used in London in the construction of sewers, 
 &c. This concrete is composed of Portland cement, 
 sand, and lime. Hydraulic lime is used for sewers and 
 waterworks, and common lime for ordinary work. The 
 lime is used in a powdered state. The whole of the ma- 
 terials are mixed in a dry state by hand, and afterwards 
 gauged in a specially made pug-mill. The least possible 
 amount of water is added by means of a fine jet while the 
 pug-mill is in motion. The mixture is then spread in 
 thin layers, and beaten by rammers formed of hardwood. 
 The quantities for coarse work, where a fine face is not 
 required, are : Portland cement, 1 part ; common lime, 
 ^2 part ; gravel, 13 parts ; coarse and fine sand, 6 parts. 
 And for sewers : Portland cement, 1-5 part ; hydraulic 
 
HOW TO USE THEM 
 
 291 
 
 lime, 1 part; sand, 6 parts. And for external work of 
 good quality: Portland cement, 1 part; lime, 1/2 part: 
 sand, 7 parts. The above proportions are all by meas- 
 ure. Specimens of Coignet beton at two years old have 
 attained a crushing strength of 7,400 lbs. to the square 
 inch. 
 
 Fine Concrete. — ''No book on plastering, " says Miller, 
 ''would be complete without a description of the meth- 
 ods for working 'fine concrete' (here termed 'fine con- 
 crete' to distinguish it from rough concrete as used for 
 foundations, &c.), which is now coming into general use 
 for paving purposes, staircases, and constructive and 
 decorative works for buildings. Floors, roofs and simi- 
 lar works which are finished with fine concrete^ being 
 within the plasterer's province, also demand description. 
 The proper manipulation of the plastic materials, which 
 is imperative for sound concrete^ is undoubtedly plaster- 
 er's work. The higher branches of concrete work, for 
 architectural construction and decoration, embrace 
 model-making, modelling, piece-molding and casting. 
 Concrete construction is therefore essentially a part and 
 parcel of the plasterer's art and craft. The construc- 
 tion of concrete staircases in situ affords a striking ex- 
 ample of the necessity of employing plasterers. Only a 
 plasterer can manipulate the materials correctly, make 
 the nosing mitres sharp and true, and set the soffits of 
 the stairs and landings, and form a true arris at the 
 stringing, whereas the non-plasterer leaves the work un- 
 even, rough and unsound. The non-plasterer can just 
 manage to spread the stuff laid on. the ground for him 
 when laying paving, but he is entirely lost when the 
 stuff has to be taken up • on a hawk and laid with a 
 trowel on an upright or overhead surface. He then gets 
 upset, or rather he upsets the stuff. The non-plasterer 
 
292 
 
 CEMENTS AND CONCRETES 
 
 possibly may have been an unfinished apprentice, or a 
 dunce at his former trade, hence his trying another. 
 These remarks are not caused by any hostility to other 
 trades, but are inspired by the fact that many failures 
 in the better class of concrete are due to the non-plaster- 
 er 's incapacity in working, and his lack of knowledge of 
 the materials. Portland cement concrete pavements were 
 first u^sed about sixty years ago. Its introduction, im- 
 provements, and subsequent rapid strides for paving, 
 and in the construction of staircases, cast and made in 
 situ, are due to the plasterers. Concrete is one of the 
 best materials for paving the sidewalks of streets, abat- 
 toirs, stables, breweries, &c. It is jointless, impervious, 
 non-slippery, and can be laid with a plain surface or 
 grooved to any desired form. The only objection to 
 paving laid in situ for streets is that when it is cut to 
 repair or alter gas or water pipes it is difficult to make 
 it good without the patches showing. This slight defect 
 can easily be overcome by cutting out the whole bay 
 where the patches are, or by forming a movable slab 
 over the pipes. 
 
 There has been in recent years some controversy as 
 to the department of the building trades to which lay- 
 ing concrete paving properly belongs. The claim is un- 
 doubtedly upheld in the strongest way for the plaster- 
 ers. A further argument, if one is needed, to identify 
 the operation as a plasterer's job, is that the tools, skill 
 in which is necessary, are exclusively those of plaster- 
 ers. The laying trowel and the hand-float are prin- 
 cipally used^ and none but plasterers exclusively employ 
 them, no other workman in any branch of the building 
 trades being habituated to their use. In every part of 
 the world where <?oncrete paving has been used it has 
 
HOW TO USE THEM 293 
 
 been laid down by plasterers, so that it may be looked 
 upon as their leg:itimate sphere of work. 
 
 Concrete is now extensively used in preference to 
 earthenware for making sewer tubes. Experience has 
 proved that the acids present in liquid sewage and the 
 gases generated by the action of a faecal decomposition 
 do not injure the concrete tubes, but on the contrary tend 
 to harden them. Among the many unlikely purposes for 
 which concrete has come into use may be mentioned stat- 
 uary, vases, fountains, sinks, tanks, cisterns, cattle- 
 troughs, silos, railway sleepers, platform copings, man- 
 telpieces, chimney pots, tall chimneys, tombs, tombstones, 
 and coffins. Concrete is slowly but surely coming to the 
 front as one of the most useful, economical, constructive, 
 and decorative materials for works requiring strength 
 and endurance. It may now be said to be indispensable 
 to the architect, engineer and builder. Concrete, when 
 properly made with a Portland cement matrix, and slag 
 or a similar aggregate, is undoubtedly the best fire-proof 
 material used in any building construction. It can be 
 made thoroughly waterproof and acid proof, and may be 
 moulded or carved to any design and colored to any 
 shade. After this brief historical review of concrete, the 
 practical considerations of the modern working by plas- 
 terers claim attention. Before describing the methods 
 of working the concrete, a description of the materials, 
 with their characteristics and application, is given as a 
 preliminary guide and reference. 
 
 Matrix. — Matrix is a word used to designate any ma- 
 terial having a setting, binding, or cementing power, 
 such as limes, plaster or cements. For concrete paving, 
 stairs, floors, or cast work for external purposes, it may 
 be truly said that there is only one matrix, namely, Port- 
 land cement. 
 
294 CEMENTS AND CONCRETES 
 
 Aggregate. — This is a term applied to those materials 
 held or bound together by the matrix. Aggregates may 
 be fibrous or non-fibrous, natural or artificial. The nat- 
 ural aggregates comprise granite, stone, shells, marble, 
 slate, gravel, sand, metal filings, &c. ; the artificial slag, 
 brick, pottery, scharff, clinkers, coke-breeze, ashes, glass, 
 &c. ; and the fibrous slag, wool, coir, fibre, reeds, hair, 
 cork, tow, chopped hay, straw, shavings, &c. The fibrous 
 aggregates while being principally of a natural kind, are 
 generally of a vegetable nature. They are commonly 
 used with a plaster matrix for the interior works. The 
 best aggregates for the upper coat of concrete paving 
 are granite, slag, and some of the hard limestones. The 
 best and cheapest for the first layer or rough coat are 
 broken bricks, old gas retorts, clinkers, whin and other 
 stones. Stone chippings from masons' yards and quar- 
 ries are cheap and good. Shingles and gravel are also 
 used, but owing to their round and smooth surfaces they 
 afford little or no key for the matrix. When found in 
 large quantities and at a cheap rate, they should be 
 broken to render them more angular, so as to give a bet- 
 ter key. Aggregates are broken by a crushing or stamp- 
 ing machine. In Paris, the stone aggregates used for 
 casting figures, vases and similar ornamental works is 
 generally broken by hand. 
 
 Aggregates should be clean, and their surfaces free 
 from mud and dust. Coarse aggregates are easily 
 cleaned by turning on a strong stream of water from the 
 hose. The aggregates should be laid on an inclined plane 
 to allow the water and dirt to run off. The importance 
 of a clean aggregate is seen from the fact that briquettes 
 made from washed particles resist a tensile strain from 
 15 to 20 per cent, higher than those made f-rom unwashed 
 particles, when tested under similar conditions. 
 
HOW TO USE THEM 
 
 295 
 
 Porous Aggregates. — All aggregates of a porous na- 
 ture or having a great suction should be well wetted 
 before being gauged, to prevent absorption of the water 
 used for gauging the matrix. A porous aggregate re- 
 quires more cement than one of closer texture, and is 
 not as strong. Water has no power to harden or set an 
 aggregate. It is used to render the mass plastic, and to 
 set the cement. No more than is necessary for this pur- 
 pose should be used. Sloppy cement will not attain the 
 same degree of hardness as a firm or stiff gauged cement, 
 consequently it stands to reason that if the water or a 
 part of it be absorbed by a porous aggregate, it will ren- 
 der the matrix, or that part next to the aggregate, friable 
 and worthless. This may be proved by gauging a part 
 of neat cement and spreading it on a brick and another 
 part on a slate. It will be found that the latter will set 
 and become hard, whilst the former will either crumble 
 before setting, or partly set, without getting hard. All 
 aggregates are more or less absorbent, but while the por- 
 ous kinds will absorb the water from the matrix, not 
 only leaving the portions in immediate contact with the 
 aggregate inert, but also weakening the whole body of 
 the concrete, the non-porous have little or no absorption, 
 water being retained in the matrix, or a portion may lie 
 on the surface of each particle of aggregate, thus tend- 
 ing to harden the matrix and increase the general 
 strength of the concrete. It may be thought that these 
 defects are trivial, and can be overcome by thoroughly 
 saturating the porous aggregate to prevent suction, but 
 the fact still remains that after this or other excess water 
 has dried out, the body of the concrete must still be por- 
 ous, and this is one, if not the principal reason, why 
 some concretes are not damp-proof. The quantity of 
 matrix used for ordinary concrete being very much less 
 
296 
 
 CEMENTS AND CONCRETES 
 
 than the quantity of aggregate, and the matrix not being 
 of sufficient thickness to resist the force of atmospheric 
 moisture, the damp finds a ready passage through the 
 porous portions. A mass of porous aggregate will ab- 
 sorb external moisture, and this will gradually work 
 through the body to the weakest or driest surface, or be 
 retained for a time, according to the state of the atmos- 
 phere. The extra keying power claimed for a porous 
 aggregate is infinitesimal. It may be said not only to be 
 of no value, but unnecessary, bearing in mind that in 
 well-made concrete every particle of aggregate is envel- 
 oped with matrix. 
 
 Another point to be considered is the great tenacity of 
 Portland cement to most clean surfaces, however smooth. 
 Many men will have noticed how it clings and adheres 
 when set to iron, even to the smooth blades of trowels 
 and shovels. The ultimate tenacity of neat Portland 
 cement after being gauged twelve months is about 500 
 lbs. per square inch. 
 
 Compound Aggregates. — The proper selection and use 
 of aggregates for a true concrete is not secondary, but 
 of equal importance to the matrix. As inferior aggre- 
 gates are in the majority, it is advisable to take their de- 
 fects into consideration. For concrete floors, roofs, and 
 stairs, where strength, durability, and fire resisting prop- 
 erites are imperative, gravel and coke-breeze as aggre- 
 gates stand lowest in the scale. Owing to their abun- 
 dance and cheapness, however, or for want of better ma- 
 terials, their use is often unavoidable. Their individual 
 defects may be partly if not wholly corrected by a com- 
 bination of two or more aggregates so as to balance their 
 respective good and bad qualities. It is self-evident that 
 the hard, non-porous, and incombustible nature of gravel 
 will correct the soft, porous, and combustible nature of 
 
HOW TO USE THEM 
 
 297 
 
 coke- breeze, and that the light, rough, angular, and elas- 
 tic nature and variety of size of coke-breeze will counter- 
 balance the disadvantages of the heavy, smooth, round, 
 and rigid nature and uniformity of size of gravel. The 
 strength, irregularity of size, and form of broken bricks 
 and its incombustible nature, causes it to be a direct gain 
 to either of the above. The mixing of various aggre- 
 gates may seem of small importance, but if by their judi- 
 cious amalgamation the strength is enhanced, or the 
 weight or cost of the material decreased, or gained, if the 
 practice enables any waste or by-product to be utilized, 
 then the advantage becomes obvious. To argue by 
 analogy, it is well known that it is by the judicious com- 
 bination and manipulation of various materials that 
 mortars and cements attain their strength and hardness, 
 therefore the same course will give equally good' results 
 with concretes, while rendering economy with safety pos- 
 sible. 
 
 The compressive and tensile strength of concrete is 
 influenced both by the matrix and the aggregate. Aggre- 
 gates which are uniform in size (or if of various sizes 
 which are not graduated in proportion to each other), or 
 having their surfaces spherical, soft or dirty, will not 
 bind with the matrix, or key or bend with each other, so 
 well as those which are of various graduating propor- 
 tional sizes, and have their surfaces hard, angular and 
 clean. 
 
 Sand and Cement. — Sand is extensively used as an 
 aggregate in Portland cement for cast work, mouldings, 
 and wall plastering. Fine sand does not give so good 
 results for strength as coarse sand, and a hard-grained 
 sand is more durable than a soft one. Ground brick- 
 bats or pottery, sandstone and flints, fine gravel, smithy 
 
298 CEMENTS AND CONCRETES 
 
 ashes, and coke-breeze are often used as substitutes for 
 sand. 
 
 It has generally been assumed that sharp coarse sand 
 is one of the best and strongest for gauging with cement, 
 but, according to experiments made by Mr. Grant, clean 
 sharp pit sand gives better results, as he found that 
 whereas test briquettes having a sectional area of 2i/^ 
 superficial inches, composed of equal proportions of 
 coarse sand, broke at the end of twelve months with a 
 tensile strain of 724 lbs., it required 815 lbs. to break 
 briquettes composed of equal parts of cement and pit 
 sand. With reference to various sands suitable for mak- 
 ing mortar with cement, Mr. Grant's experiment is of a 
 most surprising nature, as it indicates that sand made 
 from ground clay ballast, or ground brick — which are 
 identical — and Portland stone dust, were superior to pit 
 or sea sand, or smiths' ashes. 
 
 The following shows the results of tests of various 
 aggregates made by Lieutenant Innes. The briquettes 
 are composed of Portland cement, sand, or other aggre- 
 gates, in the proportions of 1 to 2, and were kept in 
 water for seven days. 
 
 It will be seen that Portland stone dust gave the best 
 results, and the others follow in this order — coarse sea 
 sand, rough pit sand, smooth pit sand, drifted sea sand, 
 and lastly smithy ashes. If the dust had been elimi- 
 nated, the tests would be more valuable. The degree of 
 coarseness has a considerable influence on the strength 
 of the concrete and mortar. Fire sand makes weaker 
 mortar than coarse. The following table gives the re- 
 sults of two series of tests carried out by Mr. Grant. 
 The cement was sifted through a sieve with 2,580 meshes 
 to the square inch, and was made into briquettes with 2 
 
HOW TO USE THEM 
 
 299 
 
 o 53 cc 
 
 A . ^ 
 
 ft ^ ^ 
 
 t-i D 
 
 
 rH 
 
 CO 
 
 00 
 
 00 
 
 
 CO 
 
 
 O 
 
 
 
 
 rH 
 
 
 
 
 
 
 
 1> 
 
 cq 
 
 a 
 
 g:> 
 
 CO 
 
 00 
 
 
 
 tH 
 
 CM 
 
 
 05 
 
 
 
 iO 
 
 05 
 
 
 
 rH 
 
 
 
 
 
 
 
 CO 
 
 rH 
 
 
 CO 
 
 rH 
 
 
 
 c4 
 
 o 
 
 
 rH 
 
 
 
 
 
 
 CO 
 
 CO 
 
 
 o 
 
 o 
 
 o 
 
 00 
 
 
 lO 
 
 00 
 
 
 
 
 o 
 
 
 CO 
 
 CO 
 
 
 T— 1 
 
 
 tH 
 
 
 iH 
 
 
 CO 
 
 CO 
 
 CO 
 
 CO 
 
 CO 
 CO 
 
 CO 
 
 CO 
 
 00 
 CO 
 
 CO 
 
 cq 
 
 CO 
 
 CO 
 
 C<1 
 
 CO 
 
 o 
 
 }2i 
 
 C3 
 
 S 
 
 o 
 
 5C 
 
 OP 
 
 a O 
 
 o ^ 
 
 2 ^ 
 
 03 
 
 13 
 O 
 
 t3 
 
 73 
 
 QQ 
 
 GO 
 
 
 
 
 
 
 
 
 
 % 
 
 
 
 OQ 
 
 OQ 
 
 
 1— H 
 
 o 
 
 
 
 a 
 
 • i-H 
 
 
 
 
 
 .s 
 
 oT 
 
 .'s 
 
 tS5 
 
 
 
 
 
 
 ii! 
 
 
 O 
 
 
 o 
 
 
 and 
 
 une 
 
 
 
 
 o 
 
 a 
 
 o 
 
 *3 
 
 03 
 
 O 
 O 
 
 s 
 
 .S 
 
 03 
 O 
 
 03 
 
 § « 
 
 Ph 
 
 o3 
 
 P-l 
 
 03 
 
 O 
 
 Ph 
 
 13 
 
 3 o 
 
 03 2 
 
300 CEMENTS AND CONCRETES 
 
 parts of sand by weight. All the briquettes are kept in 
 water. 
 
 Tensile Tests of Portland Cement and Sand (Coarse 
 AND Fine) . 
 
 No. 
 
 
 Sand 
 tested 
 
 by 
 Sieves. 
 
 At 28 
 days. 
 
 60 
 days. 
 
 91 
 days. 
 
 182 
 days. 
 
 273 
 days. 
 
 364 
 days. 
 
 
 First Series— 
 
 Nos. 
 
 lbs. 
 
 lbs. 
 
 lbs. 
 
 lbs. 
 
 lbs. 
 
 lbs. 
 
 1 
 
 1 cement to 3 sand. 
 
 20-30 
 
 78.5 
 
 113.9 
 
 116.9 
 
 142.3 
 
 178. 
 
 205.5 
 
 2 
 
 ditto. 
 
 Second Series— 
 
 10-20 
 
 137.1 
 
 239.5 
 
 223. 
 
 231.5 
 
 254.5 
 
 251.5 
 
 3 
 
 1 cement to 3 sand. 
 
 20-30 
 
 117.2 
 
 134.5 
 
 145. 
 
 156. 
 
 157.8 
 
 213. 
 
 4 
 
 ditto. 
 
 10-20 
 
 212. 
 
 236.5 
 
 206. 
 
 253. 
 
 267.5 
 
 273.5 
 
 In the above each figure is the average of ten tests, 
 the result being given in pounds per square inch. The 
 sand used in tests 1 and 3 passed a sieve with 400 meshes 
 to the square inch, and the sand used in the tests 2 and 
 4, through a sieve with 100 meshes to the square inch. 
 
 Fireproof Aggregates. — The selection of the best 
 known fire-resisting aggregate for fire-proof concrete 
 construction is of vital importance. Granite, stone, and 
 flints splinter and crack when subjected to great heat, 
 or to the sudden reaction caused by cold water used for 
 extinguishing fires. Coke-breeze concrete, when under 
 the influence of intense heat, as for example in the midst 
 of a building on fire (stated by Captain Shaw to be 
 from 2000 degrees to 3000 degrees Fahr.), will gradually 
 calcine and crack, and finally fall to dust. 
 
 Slag is one of the best fire-proof aggregates. It is a 
 well-worn axiom that ^^what has passed through the fire 
 
HOW TO USE THEM 
 
 301 
 
 will stand the fire. ' ' There is no other material that has 
 passed the ordeal of fire like slag. Its great hardness, 
 density, and angularity (when crushed) all tend to make 
 it one of the best substances for fire-proof construction. 
 Slag is cheap and abundant, but requires great care in 
 selection, as some kinds contain a large amount of sul- 
 phur, which is very detrimental to Portland cement, 
 causing the concrete to blow and expand. The presence 
 of sulphur can often be detected by the smell alone. 
 When sulphur is present in a heap that has lain for 
 some time, or sufficiently long to allow the atmosphere to 
 cleanse the outer surface, it is more difficult to detect. A 
 hole should then be dug in the heap, and the presence 
 of sulphur can be ascertained by smell, heat, and color. 
 It will smell strong, and if new will be warm, and show 
 yellow patches. The power of the sulphur is so great 
 that washing the slag once will not entirely cleanse it. 
 In some cases frequent washings and long exposures to 
 the air are necessary. There are some slags that are free 
 or nearly so from sulphur, and which can be had direct 
 from the iron furnaces. The slag from coal and iron 
 furnaces is largely employed for concrete paving. It is 
 hard and practically free from sulphur. The best size 
 is % inch screenings. This when sifted yields a fine kind 
 for topping, and the residue is useful for the rough coat. 
 
 The next best fire-resisting aggregates are fine-bricks, 
 pottery, scharff, hard clinkers, and pumice-stone. The 
 last has the advantage of being extremely light, but it is 
 too soft for the frictional wear. Coke-breeze may to a 
 certain extent be deprived of its combustible nature and 
 rendered more fire-resisting by washing and passing it 
 tlirougrh a 1/4 i^ich sieve, then adding 1 part flowers of 
 ^'ulphur and 10 parts fine broken bricks to 20 parts of 
 ^oke-breeze. The larger breeze rejected by the sieve can 
 
302 CEMENTS AND CONCRETES 
 
 be broken small, or used for internal layers of concrete. 
 The bricks should also be passed through a inch sieve. 
 The finer the breeze and brick^ the better for receiving 
 and retaining nails. 
 
 Voids in Aggregates. — The quantity of voids or in- 
 terstices depends on the shape and size of the aggregates. 
 The least quantity of voids will be found in those aggre- 
 gates which are broken small, and contain pieces of va- 
 rious sizes. Gravel free from sand contains about 30 
 per cent, of voids, and broken stone of uniform size about 
 50 per cent. Sand is often mixed with gravel, stones, 
 &c., to lessen the quantity, or fill the voids, so as to en- 
 sure the full strength of the concrete, without adding 
 more cement than the proper ratio. The following 
 method is used to ascertain the voids in aggregates: — 
 Fill a box of known capacity with damp, broken aggre- 
 gate ; start shaking it during the operation ; then fill the 
 box to the brim with water ; the quantity of water is the 
 measure of the voids in the aggregate. Having now 
 briefly reviewed the characteristics of the aggregates 
 most used, the practical conclusions to be drawn are that 
 they should be angular in form, hard in nature, grad- 
 uated in size, and clean. 
 
 Crushing Strength of Concrete. — The crushing 
 strength of concrete depends upon the ratio of cement, 
 and the nature of the aggregate. Another important 
 factor is compression, done by heating and ramming. 
 Compression increases the weight of concrete about 4 per 
 cent., and the strength about 25 per cent. The follow- 
 ing table shows the crushing strength of concrete made 
 with Portland cement and various kinds of aggregates as 
 given by Mr. Grant. The tests were made with 6-inch 
 cubes. One-half were compressed by heating the con- 
 crete into the mould with a mallet ] the other half were 
 
HOW TO USE THEM 
 
 303 
 
 not compressed. The whole were kept in the air for a 
 year before being crushed. 
 
 The granite and slag might have been expected to 
 have given the better results. It is probable that they 
 were unwashed^ and contained a considerable amount of 
 dust. If the compression was done by hydraulic power, 
 so as to obtain a uniform compression in all the cubes, 
 the results would be more reliable. 
 
 Crushing Strength (in Tons per Square Foot) op 
 Portland Cement Concretes Having Various 
 Aggregates. 
 
 Nature of Ag- 
 gregate. 
 
 Six to One. 
 
 Eight to One. 
 
 Ten to One. 
 
 Com- 
 pressed. 
 
 Not 
 Com- 
 pressed. 
 
 Com- 
 pressed. 
 
 Not 
 Com- 
 pressed. 
 
 Com- 
 pressed. 
 
 Not 
 Com- 
 pressed. 
 
 Ballast 
 
 81.6 
 
 72.8 
 
 54. 
 
 50. 
 
 42. 
 
 32. 
 
 Portland stone 
 
 162.4 
 
 120. 
 
 132. 
 
 98. 
 
 88. 
 
 76, 
 
 Granite 
 
 122. 
 
 98. 
 
 78.4 
 
 58. 
 
 62. 
 
 46. 
 
 Pottery 
 
 115.2 
 
 98.4 
 
 88. 
 
 72. 
 
 74. 
 
 56. 
 
 Slag 
 
 92. 
 
 80. 
 
 78. 
 
 56. 
 
 42. 
 
 34. 
 
 Flints 
 
 82. 
 
 62. 
 
 70. 
 
 56. 
 
 60. 
 
 51.2 
 
 Water for Concrete. — Water for concrete should be 
 perfectly clean, and free from organic and inorganic 
 impurities. As regards the quantity, it can only be 
 said that for such purposes as the foundations for pav- 
 ing, casting blocks, &c., or where the material can be 
 well rammed, so as to insure perfect consolidation, less is 
 required than where the concrete can only be poured or 
 laid in position. When mixed with sufficient water, the 
 concrete occupies about one-eighth more space than when 
 
304 CEMENTS AND CONCRETES 
 
 mixed with the full quantity, and percolation through 
 the former gauge would be greater than through the lat- 
 ter. Yet by thorough ramming the former would oc- 
 cupy less space and offer greater resistance to moisture. 
 An over-watered gauge is slow to set, difficult to work, 
 liable to surface cracks, and often there is a loss of 
 strength, caused by escape of a portion of liquid cement. 
 The work will also be unequal in strength, owing to the 
 liquid cement flowing to various or lov/er parts, leaving 
 parts of the aggregate bare and weak. 
 
 It must not be inferred from the foregoing remarks 
 that water is entirely unnecessary or of little value for 
 concrete. On the contrary, it is of the utmost value. 
 The evil is in the abuse, not in the use. Portland ce- 
 ment has a great affinity for moisture. For instance, if 
 a sack of cement is left on or in a damp place, a part of 
 the contents soon becomes set and extremely hard, which 
 is a proof of its affinity, and that moisture alone will 
 set cement without water, far less excess of water. Fresh 
 cement requires more water than stale cement. Cement 
 gauged with sea water sets more slowly than with fresh 
 water. Sea water should not be used in concrete in- 
 tended for paving stables, chemical tanks, or similar 
 places where it will come in contact with ammonia. Sea 
 water having a lower freezing-point than fresh water, is 
 sometimes used in frosty weather to allow the work to be 
 carried on. It ought not, however, to be used for ex- 
 ternal work, especially for plastering facade as it has 
 the property of attracting moisture and causing an ef- 
 florescence on the surface. Sometimes in frosty weather 
 hot water, also hot lime, is used for concrete; but al- 
 though these hasten the setting and hardening of con- 
 crete, they also wash away some of the finest and best 
 particles of the cement during the gauging. A part of 
 
HOW TO USE THEM 
 
 305 
 
 the water ako forms in little globules throughout the 
 mass, and when the water-drops evaporate a series of 
 small holes or bulbs are left, which deteriorate the 
 strength of the concrete. Finally, it may be stated that 
 the quantity of water required for gauging concrete is 
 regulated by the class and condition of the aggregate, by 
 the state of the atmosphere, and by the purpose for 
 which the concrete is required. Another important point 
 is the careful and thorough incorporation of all the ma- 
 terials when gauging. A mass of raw materials, if 
 gauged carelessly, will require more water to attain the 
 same plasticity than that which is carefully gauged. Ap- 
 proximate quantities of water are given for Portland 
 cement plastering. For concrete the quantity is about 
 21 gallons of water to 1 cubic yard of dry materials, or 
 about 1 part by volume to 8 parts. It is a good maxim 
 to bear in mind when mixing water for concrete, that 
 other things being equal, the minimum is better than the 
 maximum. Water may be said to give birth to the 
 strength of cement; to carry the simile further, the ag- 
 gregate may be termed the bone, the matrix the skin and 
 sinew, and the water the blood of concrete. 
 
 Gauging Concrete. — It is a common idea that concrete 
 can be gauged and used anyhow, with any aggregate, or 
 with any amount of water ; and in consequence of a lax- 
 ity in supervision in the selection of the materials, and 
 their correct gauging and manipulation, unsatisfactory 
 results are sometimes arrived at, the blame being at- 
 tributed to the wrong cause. Gauging concrete re- 
 quires considerable care to avoid waste of the materials 
 and obtain the best possible work. Concrete can be 
 gauged either by hand or by machinery. For small 
 quantities, such as for stairs and similar work, the 
 former is almost invariably used; and tor large quan- 
 
306 
 
 CEMENTS AND CONCRETES 
 
 tities, such as for foundations or buildings, &c., the lat- 
 ter, being" more economical, is preferable. A careful 
 and uniform method should be employed • for hard 
 gauging; nothing should be left to chance or rule of 
 thumb. The gauge-board should be sufficiently large to 
 allow the materials to be turned over without spilling, it 
 should be placed as near the work as possible, and it 
 should be cleaned after each gauge. 
 
 For fine concrete, no more than 1 cubic yard should be 
 gauged at a time. This is as much as three men can 
 properly gauge at once and in the proper time — that is, 
 before the initial sef begins. Portland cement con- 
 crete, unlike some mortars, does not improve by pro- 
 longed working. If larger quantities are desirable, then 
 more men must be employed in the gauging. All ma- 
 terials should be measured for each gauge, to ensure uni- 
 form setting and strength, and also the best work. This, 
 combined with the saving of time and materials, will re- 
 pay a hundredfold the cost of the measures. It is a 
 common yet a wrong way, when gauging for paving pur- 
 poses, to measure the aggregate by so many barrowfuls 
 to a sack of cement. Neither the aggregate nor the ce- 
 ment can be accurately measured in this haphazard way. 
 No man fills a barrow twice alike, and the cement being 
 turned out of the sacks direct onto the aggregate is apt 
 to vary, as it may contain lumps caused by damp, and 
 very often some of the finest cement is retained in the 
 sack, as more often than not it is simply drawn up and 
 then thrown on one side without shaking it, as would be, 
 or at least should be done if the cement was emptied for 
 air-shaking. The aggregate should be measured in a 
 bottomless box or frame with handles at the ends, the 
 cement in a box (with a bottom), and the water in a 
 gallon metal measure or a pail made to contain 4 gal- 
 
HOW TO USE THEM 
 
 307 
 
 Ions. Five pailfuls of this size are about sufficient to 
 gauge 1 cubic yard where the concrete can be well 
 rammed or punned. For work that is simply laid, 1 gal- 
 lon extra is required. The box frame is laid on the 
 gauge-board and filled with aggregate (in a damp state). 
 The frame is lifted off, and the aggregate spread over the 
 board until about 6 or 7 inches thick. The cement is 
 then distributed over the aggregate. The materials are 
 then gauged by three men, two with shovels, and one 
 with a rake or larry, the former facing the latter. The 
 dry materials should be carefully but energetically 
 turned over twice or even thrice, and then when being 
 turned over the third time water must be gradually ad- 
 ded by means of a rose fixed on a water-can. Water 
 poured from a pail is apt to wash parts of the cement 
 away; the water also cannot be regularly and gradually 
 distributed over the dry materials as when a rose is 
 used. The mass is again turned over twice or even 
 thrice, until thoroughly incorporated. This turning over 
 does not consist of merely turning the mass over in the 
 centre or on one place of the board, but to be effectively 
 done a shoveller should stand at each side of the board, 
 and the raker at the end to which the mass is to be first 
 turned ; the shovellers lift the stuff and spread or rather 
 scatter it on one end of the board with a jerking mo- 
 tion, and the raker further mixes the stuff by working 
 each shovelful backwards and forwards. This is repeat- 
 ed, the stuff being turned to the other end of the board, 
 after which it is turned to the center, the water being 
 added as already described. The wet mass is then turned 
 over twice in a similar manner, and finally finished in 
 the centre of the board. The shovellers in the final mix- 
 ing turn the stuff from the outside of the heap to the 
 centre, while the raker gives the final touches. After 
 
308 CEMENTS AND CONCRETES 
 
 being gauged, it should not be disturbed, but immediate- 
 ly shovelled into pails, and conveyed to the place of its 
 use. The ^ ' initial set ' ' begins nearly or as soon as gauged, 
 and any after or unnecessary disturbance tends to de- 
 stroy the setting properties of the cement. The practice 
 of gauging, and afterwards regauging or knocking it up, 
 is most objectionable, as it destroys its setting properties. 
 No more should be gauged at one time than can be con- 
 veniently laid in one operation. The gauging of this 
 valuable material should not be left entirely to unskilled 
 labor, but ought to be carried out under careful super- 
 vision. 
 
 Ramming Concrete. — The ramming, beating, or pun- 
 ning of concrete is of great importance. It compresses 
 the concrete, rendering it more dense and free from 
 voids, and forces out all superfluous water. The re- 
 sultant gain in strength, durability, and imperviousness 
 is by no means to be despised. Without compression it 
 is impossible to obtain impervious concrete. Prolonged 
 ramming, however, is dangerous, as it may be contin- 
 ued until the cement is set^ which would be a direct loss 
 of strength. For this reason, the ramming of concrete 
 made with quick-setting cement should immediately fol- 
 low the deposition of the material, and be expeditiously 
 done. The concrete should always be gauged rather 
 stiff than soft. If in the latter form, the ramming will 
 separate the more fluid portions, and produce strata of 
 different densities. When the concrete is deposited in 
 layers, the joints of each layer, if dry or exposed, should 
 be well swept and watered before the next layer is de- 
 posited. It is often advisable, especially in very dry 
 work, to brush the joints with liquid cement after they 
 have been swept and wetted. For larger constructional 
 work, the joints should also be keyed by aid of a pick, or 
 
HOW TO USE THEM 
 
 m 
 
 by inserting stones at intervals into the concrete before 
 it is set^ leaving them projecting 3 or 4 inches above the 
 level of the joint. Another method of forming a key is 
 effected by forcing a batten on edge about 2 or 3 inches 
 deep into the concrete, at the middle of the joint, and 
 when the concrete is firm or nearly set the batten is ex- 
 tracted, thus leaving a groove which forms a key for the 
 succeeding layer. 
 
 No layer that has to be left for some time, or until 
 dry, should be less than 4 inches deep. Thin layers are 
 always a source of weakness. If the successive layers 
 can be laid before the previous one is firm or set, the 
 thickness is not of so much consequence. For large 
 work, when each layer has to stand until set, the thick- 
 ness may vary from 9 to 12 or even 18 inches. Eam- 
 ming may be done by using an iron punner, or one made 
 of hardwood and bound with iron. Wooden mallets 
 and punchers or iron hand-floats are most suitable for 
 ramming stairs and cast work. The gain in strength 
 is shown in the table of the crushing strength of Port- 
 land cement concrete. 
 
 Thickness of Concrete Paving. — The thickness of con- 
 crete paving laid in situ is regulated according to the 
 purpose and the position of the work. The thickness al- 
 so depends upon the nature and solidity of the founda- 
 tions. It is obvious that a thicker paving is required 
 for a foundation that is weak or soft than for one that 
 is strong and hard. The best foundations are those com- 
 posed of strong and well-laid rough concrete. Founda- 
 tions composed of broken bricks or stone thoroughly con- 
 solidated by ramming are the next best. The thickness 
 of foundations is also regulated by the nature of the 
 soil and the subsequent traffic. Paving the sidewalks 
 of mam streets, or where the traffic is heavy and con- 
 
310 CEMENTS AND CONCRETES 
 
 tinuous, should not be less than 2 inches. For a medium 
 traffic, and on a strong foundation, a thickness of 1^^ 
 inches will be sufficient. For side streets, garden paths, 
 passages in houses, or similar places where the traffic is 
 light and limited, a thickness from 1 to l^/^ inches will 
 be ample if on a rough concrete foundation ; but if on a 
 dry ' ' dry, ' ' that is, broken brick or stone one^ the thick- 
 ness should not be less than II/2 inches. The thickness 
 for stable floors may vary from 3 to 4 inches, according 
 to the class of horses. For instance, a thickness of 3 
 inches would be ample for race or carriage horses, but 4 
 inches is necessary for heavy cart horses. The same 
 rule applies to yards, a thickness of 3 or 3^/^ inches 
 being sufficient for carriages, while 4 inches is required 
 for carts, wagons, &c. Factory floors are generally made 
 2 inches thick, but where there is machinery or wheel 
 traffic a thickness from 2^ to 3 inches is employed. By 
 computing the volume and nature of the traffic, and 
 comparing the tests of concrete paving given herein, the 
 requisite thickness will be readily obtained. It must of 
 necessity greatly depend on the class of the materials 
 and manipulation used for the paving. Like most other 
 articles, a good material will go further and last longer 
 than a bad one. 
 
 Concrete Paving, — Good pavements proclaim a city's 
 progress. Isodorus states that the Carthaginians were 
 the first people to pave streets. The subject of paving 
 and floors will be best understood by dividing it into two 
 parts — namely, paving, which is a floor surface laid and 
 resting on solid ground; and floors, by which are meant 
 floors over voids. The following items briefly embody 
 the processes used for most concrete pavings now in 
 use. Paving in situ is either laid in ^'one coat'' or 
 ^Hwo coats," the latter being in more general use than 
 
HOW TO USE THEM 
 
 311 
 
 the former, yet each method has its individual merits. 
 One-coat work is not so liable to rise or laminate as two- 
 coat work. It takes slightly less labor, the whole thick- 
 ness being laid in one operation. The aggregate is 
 either granite or slag, or both in equal proportions, 
 gauged with Portland cement in the proportion of 2 of 
 the latter to 5 of the former. Two-coat is laid with 
 two different aggregates and gauges. The first coat has 
 a cheap aggregate, such as ballast, clinkers, bricks, or 
 wliinstone, broken so that they will pass through a 1 
 inch mesh riddle, and gauged in the ratio of 1 of Port- 
 land cement to 5 of the aggregate. It is laid till within 
 1 inch of the finished surface. The second coat is laid 
 as soon as the first is set, and is composed of 1 part of 
 Portland to 2 of the aggregate, the latter being either 
 crushed granite, slag, limestone, or whinstone that will 
 pass through a 3-16 sieve. In some districts fine shingle 
 is used for the topping aggregate. 
 
 Quick-setting solutions are used to reduce the time re- 
 quired to allow the paving to harden before it is avail- 
 able for traffic. Many pavements are ruined by being 
 used before having become sufficiently hard and set. 
 Many of the so-called quick-setting materials have the 
 desired effect of setting the concrete quickly, but the 
 work in many cases is none the better for these solutions. 
 On no account should these quick-setting materials be 
 used, unless thoroughy tested and the concrete proved 
 durable by use and time. In order to protect the sur- 
 face and allow the paving to be used immediately, P. M. 
 Bruner, an American engineer and concrete specialist, 
 covers the surface of the pavement directly it is finished 
 with a thin coat of plaster or Parian cement, which ad- 
 mits of walking upon in a few hours, and resists pedes- 
 
312 CEMENTS AND CONCRETES 
 
 trian traffic until the surface proper is sufficiently hard, 
 after which it is shelled olf with a trowel. 
 
 Eureka Paving. — This is the name for an improved 
 cont^rete, which has been extensively used with good re- 
 sults for many purposes, such as pavements, floors and 
 stairs. Eureka, if not exactly one-coat work, is nearer 
 that than two-coat work, and may be said to be the 
 happy medium, or a combination of both. Eureka is 
 laid in two layers. The first is termed the ''rough 
 coat,'' and the second the ''fine coaf or "topping." 
 The topping is laid nearly as soon as the rough coat is 
 laid, just as in rendering or dubbing-out plaster work. 
 The materials and gauges are nearly alike for both 
 layers. The gauged rough stuff is laid on the founda- 
 tion, previously wetted to prevent suction, and spread 
 and beaten with an iron hand-float. The laying, spread- 
 ing and beating is continued until the rough surface 
 is within I/2 inch of the finished line. The surface of 
 the rough coat is made fair, and a uniform thickness 
 for the topping is obtained by passing a "gauge-rule" 
 across the surface. A uniform thickness of topping 
 gives an equal expansion, therefore the surface is not 
 liable to crack. The suction is also more regular, which 
 permits of the trowelling to be done with greater free- 
 dom, and without causing hard and soft places on the 
 surface. 
 
 As many alternate bays are laid as will allow of all 
 being topped and finished the same day. When the 
 number of bays to be laid in on one day has been de- 
 cided, and the last one roughened in, the first bay will 
 be firm to receive the topping. The topping is laid and 
 spread with a wooden hand-float, ruled and trowelled 
 and brushed as afterwards described in the general pro 
 cess. This method of laying a part of the thickness ot 
 
HOW TO USE THEM 
 
 313 
 
 the paving, gauging stiff and beating the mass, forces 
 it into the interstices of the broken dry foundation, and 
 not only consolidates the foundation and the rough coat, 
 but also forms a solid bed to receive the topping. The 
 topping goes in sooner and more regularly on a stiff- 
 gauged and well-beaten coat than on a soft-gauged one, 
 or than if the whole thickness of the paVing were laid 
 in one coat. 
 
 Eureka Aggregate, — The method of preparing the ag- 
 gregate for Eureka is of the utmost importance. The 
 labor expended on its preparation is more than repaid, 
 not only in the ease and rapidity when finishing, but also 
 in the satisfaction of doing a strong and workmanlike 
 job. Slag and granite is far more preferable to gravel 
 or stone as an aggregate. Slag and granite in equal 
 proportions have been used with good results. The size 
 ordered from the furnace or quarry should be % inch 
 screenings. It must be washed through a % inch sieve 
 in a tub or iron tank. The coarse part rejected by the 
 sieve to be laid aside for the rough coat. The fine ag- 
 gregate is then washed again through a fine sieve to ex- 
 tract any mud or impalpable powder, as the presence of 
 such impurities weakens the consolidating power of the 
 cement, and decreases the ultimate strength of the con- 
 crete. This fine aggregate for the topping should be 
 angular and of various graduating sizes, from that of 
 fine sharp sand to the largest size that has passed through 
 the % inch sieve. It has been proved by experience and 
 the test of time that an artificial stone made with a fine 
 aggregate has not only more resemblance to the grain or 
 texture of natural stone, but is also denser, and wears 
 better and with more uniformity, than one made with a 
 large, round, or equal-sized aggregate. The use of small 
 and angular aggregate of the graduating sizes ensures 
 
314 CEMENTS AND CONCRETES 
 
 their fitting closer and interlocking together, thus form- 
 ing a stronger bond, giving a regular key and freedom 
 for each separate piece to be coated with cement, the 
 whole forming a solid and homogeneous body with a 
 hard surface. Concrete with large or round aggregate, 
 and the various pieces disproportionate in size to each 
 other, will fit loosely and unevenly, and only touch at 
 their most prominent points, thus leaving voids, and con- 
 sequently unsound work. The voids may perchance be 
 wholly or partly filled with matrix, still this is an un- 
 necessary waste of cement. Consequently, concrete pav- 
 ing having large or round aggregate wears unevenly, and 
 leaves the large or round pieces uncoated and loose, or 
 so exposed above the surface that they soon get dis- 
 lodged, leaving a series of small holes, which sooner or 
 later wear larger and larger. Another point of import- 
 ance is that concrete with a fine hard aggregate is more 
 plastic, works freer, and has a greater compressive 
 strength than concrete with a large or soft aggregate. 
 Eureka concrete, having a fine^ clean, and regulated ag- 
 gregate, should be used for the topping of paving, steps, 
 landings, or for any class of work exposed to friction or 
 wear. It is well to remember that a good matrix will 
 not make a bad aggregate strong, although a bad ag- 
 gregate will make a good matrix weak, or rather the re- 
 sultant concrete weak. 
 
 Eureka Quantities, — The quantities for the rough 
 coat are 1 part of Portland cement and 4 parts of the 
 coarse portion of Eureka aggregate. These materials 
 must be gauged stiff, only as much water being used as 
 will allow the mass to be thoroughly mixed and plastic. 
 The quantities for the topping are 2 parts of Portland 
 cement to 5 of the fine aggregate, and gauged about the 
 consistency of well-tempered ''coarse stuff," as used for 
 
HOW TO USE THEM 
 
 315 
 
 floating. Experiments prove that neat cement is infe- 
 rior in wear-resisting qualities (sueh as frictional wear 
 and pedestrian traffic) to mixture of cement with sand 
 or other aggregate, being in fact equal to a mixture of 
 about 1 part of cement to 3 parts of aggregate. The 
 best wearing qualities are obtained by a mixture of 2 
 parts of cement to 3 of aggregate. 
 
 Levels and Falls. — Accurate levelling and adjustment 
 of the requisite falls are important features for pave- 
 ments and flooring. Levelling is the art by which the rel- 
 ative heights of any number of points are determined. 
 Falls are used to allow rain and water used for cleansing 
 purposes to run off into channels and drains. The levels 
 and falls in good buildings are generally marked, on the 
 drawings, but it is imperative that the worker should be 
 conversant with the necessary amount of falls for paving 
 purposes, as many unforeseen difficulties often arise in 
 this class of work, especially in large surfaces. The most 
 accurate and speedy way of setting out levels and falls 
 is of special service to concrete paviors. The importance 
 of these features will be readily appreciated, especially 
 where these paving preliminaries are left to the care of 
 the concrete layers. The amount of cross fall for street 
 pavements varies according to the class and position of 
 the work. The fall is also regulated by the gradient. For 
 a level stretch of paving it is generally 1 to 60, therefore 
 for a pavement 6 feet wide it would be 1 inch. The fall 
 for rising ground is usually % inch for every 2 feet in 
 the width of the pavement. The falls for stables and 
 yards are given under their respective headings. The 
 points for levelling — also for falls — are formed by driv- 
 ing wooden pegs into the ground at the most suitable 
 points. The heads of the pegs represent the finished face 
 of the pavement. They are made level with each other 
 
316 CEMENTS AND CONCRETES 
 
 by the aid of a parallel rule and a spirit-level. Inter- 
 mediate pegs may also be levelled by means of boning 
 rods. 
 
 Pavement Foundations — Good foundations for con- 
 crete paving are of primary importance, and unless the 
 bottom is firm, and the foundation is sound, the best 
 made and laid concrete will subside, crack, and be per- 
 manently spoilt. Pavements generally cover a large 
 area, and the superstructure, however strong, must have 
 a firm foundation. Foundations consist of two parts — 
 the first is the bottom ground or natural foundation ; the 
 second is the made-up or artificial foundation; but for 
 simplicity the first is termed the ^'bottom,'' and the lat- 
 ter the ''foundation.'' The latter may be "dry" or 
 ■'gauged." If the bottom is soft, it must be well ram- 
 med before laying the dry materials for the foundation, 
 or a layer of common coarse concrete for gauged work. 
 When excavating the ground to receive the foundation, 
 the depth from the intended finished surface of the 
 pavement should be about 5 inches for paving 2 inches 
 thick, 6 inches deep for paving 2% inches thick, and 7 
 inches deep for paving 3 inches thick. The above depths 
 are for dry foundations, and where the traffic is light, 
 such as side-walks, playgrounds, and passages. If the 
 bottom is soft, or the paving intended for heavy traffic, 
 the depths may be increased, and the bottom well ram- 
 med before the materials are laid. The materials for the 
 dry foundations are broken bricks, stone rubble, or other 
 hard core. They should be spread on the bottom, and 
 broken in situ. The breaking in situ tends to consoli- 
 date the bottom and the foundation. When broken, no 
 piece should be left that will not pass through a 2l^ inch 
 ring. If the paving is intended for heavy traffic (carts 
 
HOW TO USE THEM 
 
 317 
 
 or the rolling of heavy casks) it is best to have a rough 
 concrete foundation. The rough concrete should be 
 from 4 to 7 inches deep, according to the firmness of the 
 bottom and class of traffic. This concrete is composed 
 of ballast or equal parts ballast and broken bricks, coke- 
 breeze, or hard clinkers, gauged in the proportion of 1 
 of Portland cement to 5 or 6 of aggregate. It should be 
 laid to the desired fall. If lime instead of Portland ce- 
 ment is used for the rough concrete, great care should 
 be taken to thoroughly damp the surface, and allow a 
 sufficient time for the lime to expand and any lumps of 
 unslaked lime to slake, before the fine concrete is laid. No 
 paving should be laid until the rough concrete is thor- 
 oughly set. Allowance must also be made for any set- 
 tlement of the bottom^ and for any subsidence, contrac- 
 tion, or expansion of the concrete foundation. The 
 rough is not so liable to contraction or expansion as fine 
 concrete, but it is more liable to subsidence. Expansion 
 is due to the cement not to the aggregate ; and as there is 
 less cement in rough concrete than in fine, it has less 
 power of expansion, and owing to the greater amount 
 and weight of aggregate, there is the lesser power of con- 
 traction. The size of aggregate for rough concrete is 
 also larger than for fine ; consequently each piece offers 
 a greater resistance to the cement. Subsidence is due to 
 the settlement by gravitation of the aggregate to the bot- 
 tom, which takes place after the excess water, or even 
 the liquid cement, has percolated through voids or spaces 
 of badly made or laid concrete. Unequal subsidence is 
 caused by bad and unequal gauging; one gauge being 
 firm, keeps in position ; while if soft and sloppy, the ex- 
 cess water either settles in the deepest places, or escapes 
 
S18 CEMENTS AND CONCRETES 
 
 into the ground, thus allowing the body of the concrete 
 at those parts to subside. 
 
 Screeds and Sections, — Screeds are used as guides and 
 bearings for leveling and ruling off. They are general- 
 ly formed with wood rules, planed on all sides, and in 
 suitable sizes, and are termed ^'screed rules." Screeds 
 are sometimes formed with the same kind of material as 
 used for the pavement, and are termed ^ ' gauged screeds. ' ^ 
 Screed rules give the best results ; they are speedily laid ; 
 can be used at once, and form a clean and square joint 
 when laying work in sections. Screed rules are tempo- 
 rarily fixed on the foundation by laying them on narrow 
 strips of gauged concrete, and then made straight, and to 
 the proper falls, by laying the edge of a straight-edge on 
 them, and tapping with a hammer till firm and true. 
 When the bay is finished and set, the screeds are re- 
 moved by gently tapping with a hammer, leaving a clean, 
 straight, and square joint. Where there is only a small 
 quantity of screeds required, or where time will not per- 
 mit of waiting for the concrete bedding strips to set, the 
 screed rules can be fixed on gauged plaster, which al- 
 lows the screeds to be used at once. The plaster should 
 be cleaned off at the side intended to be laid; to ensure a 
 sound bed for the concrete, and a square joint. Gauged 
 screeds may be also formed with gauged coarse plaster. 
 They are best done as described for ''pressed screeds." 
 In laying large surfaces it is best to arrange the screeds, 
 so that the work can be laid in alternate sections or bays, 
 w^hich will afford greater facility to get at the work, and 
 also to allow the isolated bays to expand. For instance, 
 if laying a stretch of paving 50 feet long and 6 feet wide, 
 this would be laid out in 5-feet bays, the screed rules, 
 each 6 feet long, being laid so as to form the odd num- 
 
HOW TO USE THEM 
 
 319 
 
 bered bays to be laid and finished first. This allows the 
 workmen more freedom by standing on the empty bays 
 when finishing the laid bay. The screeds are then re- 
 moved, and the intermediate bays laid, the sides of the 
 finished bays serving as screed or bearing when ruling 
 in. Boards or bags are laid on the finished bays to pro- 
 tect the surface, and give a footing for a workman to 
 finish off the intermediate spaces. It must not be for- 
 gotten to fix the screed rules toward the curbs, also to 
 keep the ends of the screed about % inch about the curb, 
 to allow for any subsidence, and for the water to run 
 off. This also provides for the greater amount of wear 
 
 Sections of Concrete Kerb, Channel, and 
 Paving. 
 
 NO. 1. 
 
 that takes place near to than actually on the curb. The 
 foundations should be thoroughly saturated with water 
 before the screeds are fixed. If this is not done, the 
 brick or other dry material used will absorb the moisture 
 or life from the concrete, and render it dry or dead. The 
 drenching with water also frees the broken materials 
 from the dust caused by breaking the large pieces in 
 situ. In laying paving or a gauged foundation, the sur- 
 face should be well swept with a hard broom and after- 
 
320 CEMENTS AND CONCRETES 
 
 wards damped, so as to ensure the perfect cohesion and 
 solidity of the foundation and the paving. The curbs 
 and channels are sometimes made in situ, but more often 
 they are cast and laid in the same manner as ordinary 
 stone. Cast work is harder than laid work; it also al- 
 lows the paving to be laid with greater freedom. Illus- 
 tration No. 1 shows sections of the street curbing and 
 channel which may be used in connection with slab pav- 
 ing, or pavements laid in situ. 
 
 Laying Concrete Pavements. — The foundations having 
 been damped, and the rough stuff gauged, it is carried 
 in pails and emptied at the top end of the bay. The plas- 
 terer spreads it with a layer float, and rams it well into 
 the foundation. When he has laid a stretch the whole 
 width of the bay, and as far as he can conveniently reach, 
 he moves back and lays the remaining portions of the 
 bay in the same way until complete. The rough stuff 
 surface is then made fair, but not smooth, with the gauge 
 rule. The remainder of the bays are dealt with in rota- 
 tion. The fine aggregate is then gauged, and laid and 
 spread until flush with the screeds. The stuff should be 
 rather above than below the screeds, to allow for subsi- 
 dence by subsequent ramming, ruling and patting. All 
 concrete bodies over 2 inches thick should be deposited 
 in layers. Each layer should be well rammed with an 
 iron, or hardwood temp, bound with iron. Concrete 
 gains strength by compression, and consequently its 
 density, imperviousness, and durability are increased. 
 Even for 2 inch pavement better results are obtained if 
 the stuff is deposited in two layers, each layer well 
 beaten with an iron hand-float. If only II/2 inches thick, 
 it should be consolidated by being beaten with an iron 
 float. The surface is next ruled with a floating rule. 
 
HOW TO USE THEM 
 
 321 
 
 The rule is worked square or edge, and the concrete cut 
 and beaten in successive short and quick strokes. If the 
 stuff is soft and laid too full, the rule is worked loosely 
 on edge with a zigzag motion, so as to draw the excess 
 stuff and water off the surface, and leave the body full 
 and regular. If there are any hollow places, they are 
 filled up with stuff, and the rule again applied. ' In all 
 cases the surface should be finally straightened by beat- 
 ing with the rule. This process leaves the surface more 
 uniform, straight, and solid than by dragging or working 
 the rule. 
 
 Trowelling Concrete. — After being ruled, and when 
 slightly firm, the surface is beaten with a wood hand- 
 float, which lays any irregular parts or projecting pieces 
 of aggregate. The beating or patting is continued until 
 the ''fat" appears on the surface. It is then trowelled, 
 or rather ironed, the trowel being worked on the fiat of 
 the blade with a circular motion. The plasterer, when 
 trowelling off, should have a hand-float in the other 
 hand to lean on when reaching to a far off part. The 
 float is also useful to pat any dry parts. The surface 
 must be finished with a semi-dry stock-brush to obtain a 
 uniform grain. A vast amount of care is required in 
 trowelling off. Perfection can only be attained by prac- 
 tice, and a close observation of the materials, conditions, 
 and the state of the atmosphere during the progress of 
 the work. The best effects can only be attained by 
 acquiring a knack of working the trowel on the fiat, and 
 by knowing when to begin and when to leave off. It is a 
 waste of time, and the cause of an unequal surface, if 
 the trowelling is begun before the stuff is firm; but time 
 and labor will also be lost if the trowelling is left until 
 the stuff is too stiff, or has nearly set, for then the sur- 
 
822 CEMENTS AND CONCRETES 
 
 face will be rough and patchy. In either instance the 
 surface is more or less spoilt, and the ultimate appear- 
 ance and hardness seriously affected. 
 
 Grouting. — The use of neat cement for trowelling off 
 should not be resorted to (this is termed grouting''), 
 and is used when the surface is left till set, or when it 
 has not been properly patted and trowelled. The ex- 
 pansion of a strong and weak gauge being unequal, the 
 result is that the surface peels, or should it adhere, it is 
 patchy and discolored. Where grouting is unavoidable, 
 the cement should be gauged with an equal part of fine 
 aggregate, the aggregate being the same as used for the 
 topping. 
 
 Dusting. — Another bad process is that of sprinkling 
 dry neat cement over a soft surface (this is termed 
 ''dusting"), and is used to absorb the moisture caused 
 by sloppy gauging. It has draw^backs similar to grout- 
 ing. If unavoidable, the cement should be mixed with 
 line dry aggregate in the same proportion as the topping. 
 If the stuff were trowelled at the correct time, there 
 would be no necessity for grouting; and if properly 
 gauged, no need for dusting. No concrete surface can be 
 made so solid and hard as when it is finished in one body 
 and at one time. 
 
 Temperature. — It is well known that extreme heat and 
 cold effect the expansion and contraction of iron. These 
 extremes have a similar effect on concrete, especially dur- 
 ing the process of setting and hardening. Equality of 
 temperature during setting is desirable. Cold and 
 humid atmosphere retard setting; hot humidity acceler- 
 ates it. Concrete laid in cold weather stands better 
 than that laid during hot. Concrete laid in mild damp 
 weather is better than in either extreme. During high 
 
HOW TO USE THEM 
 
 323 
 
 temperatures, the surface, when sufficiently hard, should 
 be covered with damp deal saw-dust, old sacks, mats, or 
 sail-cloth, and saturated at intervals with water. If the 
 sun's rays are hot, the surface of the work while in 
 progress should be protected by extending tarpaulin or 
 sail-cloths above the parts being laid. Concrete surfaces 
 are further hardened by flooding with water, or where 
 this is not practical, covering with wet saw-dust or sand 
 as soon as set. Care must be taken that the saw-dust is 
 clean and of a light color, as otherwise it will stain the 
 work. 
 
 Non-Slippery Pavements. — Concrete pavements for 
 special purposes are rendered non-slippery by mixing Vg 
 inch lead cubes with the topping stuff. Lead cubes about 
 Y2 iiich square laid by hand from 1 inch to 4 inches 
 apart in the moist concrete surface, have been used for 
 rendering concrete surfaces non-slippery. Iron and 
 brass filings are also used for the same purpose, and also 
 for increasing the wear-resisting of concrete surface. 
 Roughened, indented, grooved, and matted surfaces are 
 also used to obtain a better foot-hold on concrete sur- 
 faces. 
 
 Grooved and Roughened Surfaces. — Stables, yards, 
 &c., are grooved and channeled on the surfaces to pre- 
 vent animals from slipping, and also to carry off urine 
 or other liquids to the traps or guUeys. Indented sur- 
 faces are useful on steep gradient to give a better foot- 
 hold. Grooves are made with a special wood or iron 
 tool, which is beaten into the surface as soon as the con- 
 crete is floated. The grooves for stables are generally 
 made about 5 inches from centre to centre, and the depth 
 about % inch. A line is first made at the one end of the 
 work, and the groover is then laid on this line, and beat- 
 
324 
 
 CEMENTS AND CONCRETES 
 
 en down with a hammer to the desired depth. Before it 
 is taken off, a parallel rule is laid on the surface and 
 against the groover, which is then taken up and laid 
 close to the other side of the parallel rule, and beaten 
 in as before, and so on until the whole surface is done. 
 The width of the parallel rule is equal to the desired 
 width between the grooves, less the width of the groover. 
 Grooves, however long, can be made by moving the tool 
 along, and against a long parallel rule. After stretch of 
 grooves have been sunk, the surface is trowelled, and the 
 indentations made true. It may be necessary to apply 
 the groover again, and beat or work it forward and back- 
 ward and further regulate their depth and straightness. 
 They are then made smooth with a gauging trowel and 
 finished with a damp brush, the sides of the grooves being 
 left smooth to give a free passage for liquids. 
 
 Grooves on a surface having a fall should radiate to- 
 ward the deepest point. A level surface may be made 
 to carry off the water by the indentation being formed 
 wider and deeper towards the outlet. Street and other 
 pavements are sometimes indented with metal rollers to 
 give a better foot-hold. Platforms and other surfaces are 
 sometimes made rough or indented by beating the moist 
 concrete, with a ' ' stamping-float. ' ' The sole has a series 
 of squares projecting about % inch, each square about 
 1 inch, and a half inch apart. Concrete surfaces are al- 
 so roughened or matted by dabbing the surface as soon 
 as trowelled with a coarse stiff whale-bone brush. Illus- 
 tration No. 2 shows three designs of grooved surfaces for 
 carriage drives, conservatories, &c. A plain border, or 
 one with a single width of the main design, is generally 
 formed on the sides and ends of the floor. A rough mat- 
 
HOW TO USE THEM 
 
 325 
 
 ted surface may also be obtained by pressing or beating 
 a wet coarse sack or matting over the moist concrete. 
 
 Stamped Concrete. — Various materials and methods 
 are used for stamping or indenting concrete surfaces to 
 obtain a better foot-hold, or to form any desired pattern. 
 Iron stamps are generally used, but owing to their 
 weight and rigid nature, are unsuitable for large sec- 
 Fig. I. Fig. 2. Fig. 3. 
 
 m\ 
 
 =4 1 
 
 
 ^^^^^^^ 
 
 =^■111 
 
 
 
 
 
 
 Three Examples of Grooved Surfaces. 
 NO. 2. 
 
 tions. Plaster stamps are sometimes used for temporary 
 purposes, or for small sections and quantities. Stamps 
 for large concrete surfaces should be composed of a ma- 
 terial that is easily made to the desired form durable 
 and slightly flexible. 
 
 Expansion Joints, — Compressive or flexible joints are 
 used to allow for any expansion or contraction that may 
 take place in a large area of concrete exposed to atmos- 
 pheric changes. There are various methods in use for 
 
326 CEMENTS AND CONCRETES 
 
 the purpose. The first is to set out the area in small 
 sections, and to lay them in alternate or isolated bays, 
 thus giving time for their expansion before the inter- 
 mediate bays are laid. This method, by dividing the 
 area into small sections, is the best for preventing cracks, 
 because small sections are stronger than large ones ; and 
 in the event of any subsidence in the foundation, the 
 surface fissures are limited to the immediate joints of 
 the section. Contraction and expansion is also less in 
 small bodies than in larger ones. 
 
 Another method of forming joints is by cutting with a 
 wide chisel or a cutting tool before the rough concrete is 
 set, a corresponding joint being cut in the fine concrete 
 topping. False joints are made by indenting the top- 
 ping after it is trowelled. A metal roller is used for 
 finishing true joints and forming false joints. Frame 
 strong enough to resist the expansion of the concrete 
 would not only increase the density and strength of 
 concrete paving and blocks, but also effectually prevent 
 its cracking. 
 
 Another method for forming sections in large sur- 
 faces of pavement of floors to prevent cracks is effected 
 thus: — first set out the size of proposed sections on the 
 rough or first coat, then with a straight-edge, a wide 
 chisel, or a cutting tool and a hammer, cut through the 
 rough coat, so as to divide it into sections as set out. 
 This done, insert wood strips into the cutting, keeping 
 their top edges about i/8 iiich below the screeds or rules 
 which represent the finished surface. The strips are 
 made from % to 1% inches wide, 3-16 inch thick, and in 
 suitable lengths. The width is regulated according to 
 the thickness of the paving. For instance^ for two inch 
 paving the widths should be 1% inches. This allows 
 
HOW TO USE THEM 
 
 327 
 
 about % inches in the rough coat (with l^ inch play 
 from the bottom), and about % inch in the topping, and 
 Vg inch for the upper thickness of the topping to cover 
 the top edges of the strips. After the strips are inserted 
 the rough coat is beaten up or made good to the sides of 
 the strips, and then the topping is laid and trowelled in 
 the usual way. The surface joints are then made direct- 
 
 -Half Plan of Coach Yard, with 
 Section through Centre. 
 
 NO. 3. 
 
 ly over the strips, with the aid of a straight edge, so as 
 to form a clean and sharp joint. As already mentioned, 
 these strips allow for any subsequent contraction or ex- 
 pansion, thus avoiding zigzag cracks ; and in the event of 
 repairs to underneath pipes, each section can be cut out 
 and relaid separately without injury to the adjoining 
 sections. This process of inserting strips in the rough 
 coat, cutting nearly through the topping, gives the same 
 results as if the strips were laid flush with the surface 
 of the topping, with the advantages that the surface can 
 be more readily trowelled, and is more pleasing to the 
 
328 
 
 CEMENTS AND CONCRETES 
 
 eye, because the strips are not seen. A cutting tool is a 
 blade of steel about 5 or 6 inches long and 4 inches wide, 
 with a wood handle at one end. The section of the blade 
 is well tapered, so as to obtain a sharp cutting edge, and 
 form a wide top edge to offer a broad surface for the 
 hammer while being beaten. 
 
 Washing Yards4 — Eureka concrete being of a hard 
 nature, and having a close and smooth surface, is well 
 adapted as a flooring for all washing or cleaning pur- 
 poses. The surface being smooth, it can in turn be read- 
 ily cleaned. Illustration No. 3 shows the half plan of 
 washing yard for washing carriages, &c. 
 
 Stahle Pavements. — The paving for stables, and other 
 places for keeping animals, should be jointless, non-ab- 
 sorbent, hard, and durable. Such paving must not be 
 slippery, yet smooth enough to be easily washed, the 
 whole laid to falls, and grooved to give an easy and 
 ready passage for liquid manure and water when being 
 washed. No material can so fully meet these require- 
 ments as a well-made and well-laid concrete. Granite 
 sets are hard, but slippery. Bricks are too absorbent; 
 the urine percolates between the joints and generates 
 ammonia and other effluvia which are detrimental to the 
 health of the animals. (See Nos. 4 and 5.) 
 
 Stables are generally laid with a fall toward the main 
 channel. The amount of fall varies according to ideas 
 of the horse owners. The fall adopted by the War office is 
 1 in 80 from the top of the manger to the main channel, 
 and 1 to 36 from each side of the stall to the centre groove. 
 The width of the main channels is usually set out with 
 screed rules, which also act as screeds to work from.. 
 Channels are generally formed after the other surface is 
 finished. Sometimes templates are fixed on the bed of 
 
HOW TO USE THEM 
 
 329 
 
 the channels, and the space filled in and ruled off with a 
 straight-edge while the whole surface is being formed. 
 The thickness of stable paving varies from 2 to 
 inches, according to the class of horse. The thickness of 
 the stalls is often decreased toward the manger. 
 
 The most useful length is 2 feet 6 inches. They can 
 be cut with a chisel as easy as cutting stone. Special 
 slabs can be made for circular work, also with rebated 
 sinking for metal plates, to cover coal-holes, drains, gas 
 and w^ater taps, &c. Concrete paving slabs are laid in 
 precisely the same way as natural stone. 
 
 .... ^^^^y^^-^-'^^^ fP. » - /Sechon <f side ^rav^ C 
 
 SeclioTV cf Chatrnet a? ^ 
 
 CJ^armelT'u^ih iron p-raTf /5ec?«bw cf cfntre proves 2> 
 
 •Sections of the various Parts of the Stable Floors 
 
 SHOWN on Illustration 
 NO. 4. NO. 5. 
 
 Concrete Slab Moulds. — Slab moulds are made With 
 iy2 inch boards ledged together. On this ground, wood 
 sides and ends (each being 21/^ inches by 2 inches, or 3 
 inches by 3 inches, according to the desired thickness of 
 slab) are fixed. One side and end is held in position 
 with thumb screws, which fit into iron sockets, so that 
 they can be unscrewed to relieve the slab when set. The 
 bottom and the sides and ends are lined with strong iron 
 or zinc plates. 
 
330 
 
 CEMENTS AND CONCRETES 
 
 Slab Making. — Slabs are mostly made by machinery. 
 The materials are 1 part of Portland cement mixed dry 
 with 2% parts of crushed granite and slag in equal pro- 
 portions that have been washed and passed through a % 
 inch sieve. They are thoroughly incorporated together 
 in a horizontal cylinder worked by machinery, a mini- 
 mum of water being added, and the mixing continued 
 until the mass is well gauged. The mould, which has 
 been previously oiled, is placed on a shaking machine 
 known as a ^ ^ trembler ' ' or ^ ^ dither, ' ' which gives a rapid 
 vertical jolting motion to the mould and its contents. A 
 small portion of ^'slip," that is, neat cement, is laid 
 round the angles. The machine is then started, and the 
 concrete laid on the mould by small shovelfuls at a time, 
 a man with a trowel spreading it over the mould until 
 full. The surface is then ruled off. If both sides of the 
 slabs are required for use, the upper surface is trowelled. 
 The whole operation of mixing, filling in, and ruling off 
 takes about seven minutes. The filled moulds are re- 
 moved and allowed to stand for about three days. The 
 slabs are then taken out, and stacked on edge and air- 
 dried for about five days. They are then immersed in 
 a silicate bath for about seven days, and are afterwards 
 taken out and stacked in the open air until it is required 
 for use. They should not be used until three months 
 old. Paving slabs are also made by hand, by ramming 
 and beating the moist concrete into the mould with an 
 iron hand-float. Powerful ramming, trituration, or vio- 
 lent agitation of the gauged material in the mould, tend 
 to consolidate concrete, and it is possible to further in- 
 crease homogeneity by the use of hydraulic pressure. 
 
 Induration Concrete Slabs. — The surface of concrete 
 slabs or other work exposed to friction or wear may be 
 
HOW TO use; them 
 
 331 
 
 hardened by soaking in a silicate solution. Silicate of 
 soda has a great affinity for the materials of which con- 
 crete is composed, and by induration causes the surface 
 to become hard, dense, and non-porous. 
 
 The silicate of soda and potash is known as soluble 
 glass or dissolved flint. The soluble silicate is a clear 
 viscous substance made from pure flint and caustic soda, 
 which is digested by heat under pressure indigester. Its 
 strength is technically known as 140 degrees, which 
 shows 1,700 on a hygrometer. When used as a bath for 
 concrete, it is diluted with water, the proportion vary- 
 ing from 6 to 10 parts of water to one of silicate. Con- 
 crete pavements, laid in situ, may also be hardened by 
 washing with silicate solution. They should not be sili- 
 cated until two days after being laid, to allow the mois- 
 ture to evaporate and the silicate to penetrate. 
 
 Mosaic, — The art of making mosaic is at the present 
 time scarcely within the province of plasterers, but in 
 former times many kinds were made in situ or in slabs 
 by plasterers. The subdivision of labor has to a great 
 extent caused mosaic-making to be conflned to special- 
 ists. Concrete is still made by plasterers. A brief de- 
 scription of this and other kinds may prove useful as 
 well as" interesting, especially to plasterers who are in 
 the habit of fixing tiles and working in concrete. Mosaic 
 is the art of producing geometrical, floral, or figured de- 
 signs, by the joining together of hard stones, marbles, 
 earthenware, glass, or artificial stone, either naturally 
 or artificially colored. The term ^ ^mosaic'' embraces a 
 wide range of artistic processes and materials for the 
 decoration of floors, walk, ceilings. The Egyptians were 
 experts in mosaic. The Cairo worker as a rule had no 
 drawings made beforehand, but the mosaic design was 
 
332 
 
 CEMENTS AND CONCRETES 
 
 constructed by the artist as he arranged the pieces on 
 the ground. The mosaic pavements of Cairo are of a 
 slightly different character from those used for wall 
 decoration, and are generally composed entirely of mar- 
 ble tesserae (and sometimes red earthenware) of larger 
 size than the delicate pieces included in wall mosaics. 
 They are arranged to form geometrical patterns within 
 a space of about two feet square. Each square slab is 
 made separately, and the pieces are set, not in plaster, 
 but in a composition of lime and clay impervious to 
 water. The clay must be unbumt, just as it comes from 
 the pit. Saracenic mosaic in Egypt is a combination of 
 the tesselated method with a large proportion of sectile 
 mosaic. The Romans also were great workers in mosaic. 
 The mosaics of Byzantium and Ravenna consisted of 
 cubes of opaque and colored glass. , % 
 
 The general method used here for pavement mosaic is 
 as follows : The repeated design is traced on stout paper 
 and small pieces of marble, or more often tile, are 
 gummed on the paper, following the design of form and 
 color, one piece at a time (with the smooth face down- 
 wards) being laid until the design is completed. The 
 mosaic slabs, which are thus temporarily kept in posi- 
 tion, are sent to the building and laid where intended. 
 A rough concrete foundation, which has previously been 
 made level, is then floated with Portland or Keen's 
 cement, and the slabs with paper are then damped and 
 drawn off, and any openings or defects filled up with 
 small pieces of the same form and color as the design. 
 The slabs are made in various sizes according to the de- 
 sign. For instance, a border 12 inches' wide may be made 
 from 3 to 6 inches long. When laying the slabs, it is best 
 to begin at the centre and work outwards, and any ex- 
 
HOW TO USE THEM 
 
 333 
 
 cess or deficiency taken off or made up in the plain part 
 of the border at the walls. The tiles are made at pottery 
 works in the required sizes and colors. The thickness is 
 generally about i/4 i^ch and the average surface size 
 about % inch. Females are often employed fixing the 
 pieces on the paper. The designs of coats of arms, mono- 
 grams, dates, figures, flowers, and foliage are effectively 
 produced by this simple and cheap process. 
 
 Concrete Mosaic. — All mosaics are more or less of a 
 concretive nature, and the trade term of concrete mo- 
 saic" is due to the fact that the matrix used is Portland 
 or other cement gauged with -the marble aggregate, and 
 laid in most cases in a similar manner as ordinary con- 
 crete. Concrete mosaic is extensively used for paving 
 halls, corridors, conservatories, terraces, &c. It is also 
 used for constructing steps, landings, baths, pedestals, 
 &c. Slabs and tiles made of this class of mosaic for 
 paving purposes are slowly but surely proving a for- 
 midable rival to Italian mosaic encaustic tiles. It can 
 be made in larger sections, thus facilitating rapidity of 
 laying. It is more accurate in form^ durable, non-slip- 
 pery, and cheaper. The last reason alone is a faVorable 
 item in this keen age of competition. Where marble has 
 been scarce, broken tiles, pottery, colored glass, flints, 
 white spar, &c., have been used as aggregate. If the 
 marble chips are obtainable as a waste, and near the place 
 of manufacture, the primary cost is small. If the moulds 
 are of metal, and made in sections so as to form a series 
 of moulds in one case, and the casts are pressed by means 
 of a hydraulic power, the cost of production is reduced 
 to a minimum. If the casts are polished in large num- 
 bers by machinery on a revolving table, the total cost is 
 further reduced. For local purposes they can be made 
 
334 CEMENTS AND CONCRETES 
 
 by hand at a medium cost. Slabs are made in almost 
 any size, but generally from 4 to 6 feet superficial. The 
 thickness varies from 1 to l^/^ inches. Tiles are usually 
 made about 10 inches square and 1 inch thick. The tiles 
 are generally made with a face of cement and white mar- 
 ble, or white and black marble chippings. They are 
 backed up with a cheaper aggregate. Various tints of 
 the face matrix are obtained by mixing the cement with 
 metallic ovides. The tiles are made in wood or metal 
 moulds, with metal strips to form the divisions of form 
 and color in the design. If the design is fret pattern, 
 the gauged material is put in between the strips that 
 form the band of the fret. When the stuff is nearly set, 
 the strips are taken out, and the other part filled in with 
 another color. Sometimes the band or running designs 
 are cast in a separate mould, and when set placed in posi- 
 tion in a larger mould, and the ground filled in, cover- 
 ing and binding the whole in one tile. Another plan is 
 to lay a thin coat of cement on the face of the mould, 
 forming the design with small marble chips by hand, by 
 pressing the marble into the cement as desired. When 
 it is firm, it is backed up with the ordinary stuff, and 
 when set, they are ground and polished. 
 
 Concrete Mosaic Laid ''in Sihi.^^ — Pavements for 
 halls, passages, shops, landings, &c., are also done in situ. 
 A rough concrete foundation is first laid fair to falls 
 and levels within % inch of the finished surface line. 
 This % inch space is to receive the plastic marble mo- 
 saic. The main or centre part is generally done first 
 and the border last. This allows a walking space or 
 bearing for boards, laid from side to side to work on 
 when laying the centre. A plank sufficiently strong to 
 keep one or two crossboards from touching the work is 
 
HOW TO USE THEM 
 
 335 
 
 laid along each side. On the side planks the crossboards 
 are laid, and moved about when required. The width of 
 the border is marked on the floor, and wood screed rules 
 laid level to the marks to form a fair joint line for the 
 border, also as a screed when floating the centre part. 
 The screed rules are generally fixed with a gauge plaster, 
 which is quicker than fixing on gauged cement. After 
 the centre is laid, the plaster should be carefully swept 
 off, and the concrete well wetted before the border is laid. 
 The marble and cement is gauged in the proportion of 2 
 of marble to 1 of cement, and laid flush with screeds, 
 laying and beating it in position with a long wood hand- 
 float. The surface is ruled in from screed to screed with 
 a straight-edge. The surface is then ironed with a lay- 
 ing trowel until it is smooth and fair. If the marble 
 does not show, or is not regular, or is insufficient, the 
 bare parts are filled in with marble by hand. When 
 marble is scarce, the % inch of the top surface is laid in 
 two coats, the first being composed of cement and a 
 cheaper aggregate, such as broken stone, tiles, &c., and 
 gauged in the same proportion as the upper or marble 
 coat. It is laid about i/4 ^^ch thick, and when it is firm, 
 but not set, the marble coat is laid as before directed. 
 The first coat saves the marble, and being firm, tends to 
 keep the marble in the upper coat from sinking. The 
 top coat is sometimes sprinkled over with fine marble 
 chips by hand or through a fine sieve, then pressed into 
 the surface and ironed with a laying trowel. Before 
 ironing the surface, care should be taken that the chips 
 are equally distributed, also that their fiat surfaces are 
 uppermost, and that the matrix and chips are perfectly 
 solid and free from ridges and holes. After the centre 
 is laid and the screeds removed, the border is laid in a 
 
336 CEMENTS AND CONCRETES 
 
 similar way. If there are two or more colors or forms in 
 the border, the divisions are formed with narrosv screed 
 rules, and arranged so that as many as practicable can 
 be laid at the same time. This allows the various parts 
 to set at one time, and saves waiting for each separate 
 part to set. The screed rules for circular work or angles 
 are formed with strong gauged plaster and then oiled. 
 
 The marble chips are either broken by hand or in a 
 stone-breaking machine. The chips vary in size from 
 1-10 to l^ inch. The best colors for borders are a black 
 matrix with white marble or spar chips, or a white 
 matrix with black marble chips. The white matrix is 
 obtained by mixing the marble dust (produced when 
 breaking the marble into chips) with a light colored 
 Portland cement. The centres can be made in various 
 tints, but the most general is a w^arm red, which is ob- 
 tained by mixing the cement with red oxide. Cement 
 colored with red oxide should be laid first, as it is liable 
 to stain other parts of a lighter color. When the centre 
 and border are laid, the floor is left until the whole is 
 perfectly set and hard, and it is then fit to polish. This 
 is done by means of a stone polisher, water and marble 
 dust, or fine slag powder. The stone polisher is a piece 
 of hard stone from 8 to 12 inches square, and about 3 
 inches thick, into which an iron ring is inserted and se- 
 cured with lead. A wooden handle from 4 to' 6 feet long, 
 with an iron hook at one end, is inserted into the ring, 
 so that the handle is firm on the stone, yet has sufficient 
 play to be moved freely backwards and forwards. The 
 polishing should not be attempted until the stuff is thor- 
 oughly set, because the polishing will destroy the face 
 of the cement, and cause a vast amount of extra labor in 
 grinding the surface down until free from holes. Small 
 
HOW TO USE THEM 
 
 337 
 
 parts of the gauged stuff should be set aside as tests for 
 determining when the stuff is set. Concrete mosaic, 
 where economy is desirable, will make a strong, durable, 
 and waterproof floor, and an excellent substitute for 
 higher class mosaics. 
 
 A Bulletin (No. 235), prepared by P. S. Wormley for 
 the U. S. government on cement, mortar, and concrete, 
 from which I quote at length, contains some excellent in- 
 formation and instructions on the preparation and the 
 use of the above materials. This bulletin is intended for 
 free distribution and may be obtained by making appli- 
 cation to the U. S. Department of Agriculture, Wash- 
 ington, D. C. 
 
 Storing Cement. — In storing cement care must be ex- 
 ercised to insure its being kept dry. When no house or 
 shed is available for the purpose, a rough platform may 
 be erected clear of the ground^ on which the cement may 
 be placed and so covered as to exclude water. When 
 properly protected, it often improves with age. Cement 
 is shipped in barrels or bags, the size and weight of 
 which usually are given. 
 
 Cement Mortar. — Cement mortar is an intimate mix- 
 ture of cement and sand mixed with sufficient water to 
 produce a plastic mass. The amount of water will vary 
 according to the proportion and condition of the sand, 
 and had best be determined independently in each case. 
 Sand is used both for the sake of economy and to avoid 
 cracks due to shrinkage of cement in setting. Where 
 great strength is required, there should be at least suffi- 
 cient cement to fill the voids or air spaces in the sand, 
 and a slight excess is preferable in order to compensate 
 for any uneven distribution in mixing. Common propor- 
 tions for Portland cement mortar are 3 parts sand to 1 
 
338 CEMENTS AND CONCRETES 
 
 of cement, and for natural cement mortar, 2 parts sand 
 to 1 of cement. Unless otherwise stated, materials for 
 mortar or concrete are considered to be proportioned by 
 volume, the cement being slightly shaken in the measure 
 used. 
 
 A ''lean'' mortar is one having only a small propor- 
 tion of cement, while a ''rich'' mixture is one with a 
 large proportion of cement. "Neat" cement is pure 
 cement, or that with no admixture of sand. The term 
 ' ' aggregate ' ' is used to designate the coarse materials en- 
 tering into concrete — usually gravel or crushed rock. 
 The proportion in which the three elements enter into 
 the mixture is usually expressed by three figures sepa- 
 rated by dashes — as, for instance, 1-2-5, meaning 1 part 
 cement, 2 parts sand, and 5 parts aggregate. In the 
 great majority of cases cement mortar is subjected only 
 to compression, and for this reason it would seem nat- 
 ural that, in testing it, to determine its compressive 
 strength. The tensile strength of cement mortar, how- 
 ever, is usually determined, and from this its resistance 
 to compression may be assumed to be from 8 to 12 times 
 greater. A direct determination of the compressive 
 strength is a less simple operation, for which reason the 
 tensile test is in most cases accepted as indicating the 
 strength of the cement. 
 
 Mixing. — In mixing cement mortar it is best to use a 
 platform of convenient size or a shallow box. First, de- 
 posit the requisite amount of sand in a uniform layer, 
 and on top of this spread the cement. These should be 
 mixed dry with shovels or hoes, until the whole mass ex- 
 hibits a uniform color. Next, form a crater of the dry 
 mixture, and into this pour nearly the entire quantity of 
 water required for the batch. Work the dry material 
 
HOW TO USE THEM 
 
 339 
 
 from the outside toward the centre, until all the water 
 is taken up, then turn rapidly with shovels, adding water 
 at the same time by sprinkling until the desired consist- 
 ency is attained. It is frequently specified that the mor- 
 tar shall be turned a certain number of times^ but a bet- 
 ter practice for securing a uniform miixture is to watch 
 the operation and judge by the eye when the mixing has 
 been carried far enough. In brick masonry the mis- 
 take is frequently made of mixing the mortar very wet 
 and relying upon the bricks to absorb the, excess of 
 water. It is better, however, to wet the brick thoroughly 
 and use a stiff mortar. 
 
 Grout. — The term ''grouf is applied to mortar mixed 
 with an excess of water, which gives about the consist- 
 ency of cream. This material is often used to fill the 
 voids in stone-masonry^ and in brick work the inner por- 
 tions of walls are frequently laid dry and grouted. The 
 practice in either case is to be condemned, except where 
 the conditions are unusual, as cement used in this way 
 will never develop its full strength. 
 
 Lime and Cement Mortar. — L. C. Sabin finds that in 
 Portland cement mortar containing three parts sand to 
 1 of cement, 10 per cent, of the cement may be replaced 
 by lime in the form of paste without diminishing the 
 strength of the mortar, and at the same time rendering it 
 more plastic. In the case of natural cement mortar, lime 
 may be added to the extent of 20 to 25 per cent, of the 
 cement with good results. The increased plasticity due 
 to the addition of lime much facilitates the operation of 
 laying bricks, and has caused lime and cement mortar to 
 be largely used. 
 
 Cement Mortar for Plastering. — In plastering with 
 cement^ a few precautions must be observed to insure 
 
340 CEMENTS AND CONCRETES 
 
 good and permanent results. The surface to receive the 
 plaster should be rough, perfectly clean, and well satu- 
 rated with water. A mortar very rich in cement is 
 rather a drawback than otherwise on account of shrink- 
 age cracks, which frequently appear. The mortar, con- 
 sisting of two or three parts sand to one of cement, 
 should be mixed with as litt4e water as possible and well 
 worked to produce plasticity. It is essential that the 
 plaster be kept moist until it has thoroughly hardened. 
 
 Materials for Making Concrete Sand, — In securing 
 sand for mixing mortar or concrete, if it is possible to 
 select from several varieties, that sand should be chosen 
 which is composed of sharp, angular grains, varying in 
 size from coarse to fine. Such sand is, however, not 
 always obtainable, nor is it essential for good work. Any 
 coarse-grained sand which is fairly clean will answer 
 the purpose. If gravel, sticks, or leaves be present they 
 should be removed by screening. The voids in sand vary 
 from 30 to 40 per cent., according to the variation in 
 size of grains. A sand with different-sized grains is to 
 be preferred, because less cement is required to fill the 
 voids. By mixing coarse and fine sand it is possible to 
 reduce the voids considerably. 
 
 It is customary to use the terms river sand,'' ^^sea 
 sand,'' or ^^pit sand," according to the source of the 
 supply. River sand as a rule has rounded grains, but 
 unless it contains an excess of clay or other impurities, it 
 is suitable for general purposes. When river sand is of 
 a light color and fine-grained it answers well for plaster- 
 ing. 
 
 Sea sand may contain the salts found in the ocean. 
 The tendency of these salts to attract moisture makes it 
 
HOW TO USE THEM 
 
 341 
 
 advisable to wash sea sand before using it for plastering 
 or other work which is to be kept perfectly dry. 
 
 Pit sand for the most part will be found to have 
 sharp, angular grains, which make it excellent for mor- 
 tar or concrete work. Where clay appears in pockets it 
 is necessary either to remove it, or else see that it is 
 thoroughly mixed with the sand. The presence of gIslj in 
 excess frequently makes it necessary to wash pit sand 
 before it is suitable for use. 
 
 The results of tests made in this laboratory would in- 
 dicate that the presence of clay, even in considerable 
 amounts, is a decided benefit to ' ' lean ' ' mortars, whereas 
 it does not appreciably affect the strength of a rich 
 mixture. 
 
 Gravel, — It is important that gravel for use in con- 
 crete should be clean, in order that the cement may prop- 
 erly adhere to it, and form a strong and compact mass. 
 As with sand, it is well to have the pieces vary in size, 
 thereby reducing the voids to be filled with mortar. The 
 voids in general range from 35 to 40 per cent. 
 
 Crushed Stone. — The best stone for concrete work con- 
 sists of angular pieces, varying in size and having a 
 clean, rough surface. Some form of strong and durable 
 rock is to be preferred, such as limestone, trap, or gran- 
 ite. The total output of the crusher should be used be- 
 low a maximum size, depending upon the nature of the 
 work in hand. All material under % inch will act as so 
 much sand and should be considered as such in propor- 
 tioning the mixture. Precautions must be taken to in- 
 sure a uniform distribution of the smaller pieces of stone, 
 otherwise the concrete will have an excess of fine ma- 
 terial in some parts and a deficiency in others. 
 
342 
 
 CEMENTS AND CONCRETES 
 
 Less than 8 per cent, of clay will probably not seri- 
 ously impair the strength of the concrete, provided the 
 stones are not coated with it, and may even prove a 
 benefit in the case of lean mixtures. The voids in crushed 
 stone depend upon the shape and variation in size of 
 pieces, rarely falling below 40 per cent., unless much 
 fine material is present, and in some cases reaching 50 
 per cent. A mixture of stone and gravel in equal parts 
 makes an excellent aggregate for concrete. 
 
 Stone Versus Gravel, — It would appear from tests that 
 crushed stone makes a somewhat stronger concrete than 
 gravel, but the latter is very extensively used with uni- 
 formly good results. This superiority of stone over 
 gravel for concrete work is attributed to the fact that the 
 angular pieces of stone interlock more thoroughly than 
 do the rounded pebbles, and offer a rougher surface to 
 the cement. A point in favor of gravel concrete is that 
 it requires less tamping to produce a compact mass than 
 in the case of crushed stone. Then, too, the proportion 
 of voids in stone being usually greater than in gravel, 
 means a slight increase in the cost of concrete. 
 
 Cinders. — Cinders concrete is frequently used in con- 
 nection with expanded metal and other forms of rein- 
 forcement for floor construction, and for this purpose it 
 is well adapted on account of its light weight. Its poros- 
 ity makes it a poor conductor of heat and permits the 
 driving of naik. Only hard and thoroughly burned cin- 
 ders should be used, and the concrete must be mixed 
 quite soft so as to require but little tamping and to avoid 
 crushing the cinders. Cinder concrete is much weaker, 
 both in tension and compression, than stone or gravel 
 concrete, and for this reason admits only of light rein- 
 forcement. 
 
HOW TO USE THEM 
 
 343 
 
 Concrete. — General Discussion : Cement concrete is 
 the product resulting from an intimate mixture of 
 cement mortar with an aggregate of crushed stone, 
 gravel, or similar material. The aggregate is crushed or 
 screened to the proper size as determined from the char- 
 acter of the work. In foundation work, stone or gravel 
 3 inches in size may be used to advantage, whereas in the 
 case of moulded articles of small sectional area, such as 
 fence posts, hollow building blocks, &c., it is best to use 
 only such material as will pass a I/2 inch screen. An 
 ideal concrete, from the standpoint of economy, would 
 be that in which all voids in the aggregate were com- 
 pletely filled with sand, and all the voids in the sand 
 completely filled with cement, without any excess. Un- 
 der these conditions there would be a thoroughly com- 
 pact mass and no waste of materials. 
 
 It is a simple matter to determine the voids in sand 
 and also in the aggregate, but in mixing concrete the 
 proportions vary a great deal, depending in each case 
 upon the nature of the work and the strength desired. 
 For example, in the construction of beam?? and flour pan- 
 els, where maximum strength with minimum weight is 
 desired, a rich concrete should be used, whereas in mas- 
 sive foundation work, in which bulk or weight is the 
 controlling factor, economy would point to a lean mix- 
 ture. When good stone or gravel is used, the strength of 
 the concrete depends upon the strength of the mortar em- 
 ployed in the mixing and the proportion of mortar to 
 aggregate. For a given mortar the concrete will be 
 strongest when only enough mortar is used to fill the 
 voids in the aggregate, less strength being obtained by 
 using either greater or less proportion. In practice it is 
 
344 
 
 CEMENTS AND CONCRETES 
 
 usual to add a slight excess of mortar over that required 
 to fill the voids in the aggregate. 
 
 It is more accurate to measure cement by weight un- 
 less the unit employed be the barrel or sack, because 
 when taken from the original package and measured in 
 bulk there is a chance of error due to the amount of 
 shaking the cement receives. As it is less convenient, 
 however, to weigh the cement, it is more usual to 
 measure it by volume, but for the reasons stated this 
 should be done with care. 
 
 Proportioning Materials. — For an accurate determina- 
 tion of the best and most economical proportions where 
 maximum strength is required, it is well to proceed in 
 the following way: First, proportion the cement and 
 sand so that the cement paste will be 100 per cent, in ex- 
 cess of the voids in sand; next, determine the voids in 
 the aggregate and allow sufficient mortar to fill all voids, 
 with an excess of 10 per cent. 
 
 To determine roughly the voids in gravel or crushed 
 stone prepare a water-tight box of convenient size and 
 fill with the material to be tested, shake well and smooth 
 off even with the top. Into this pour water until it rises 
 flush with the surface. The volume of water added, 
 divided by the volume of the box, measured in the same 
 units, represents the proportion of voids. The propor- 
 tion of voids in sand may be more accurately determined 
 by subtracting the weight of a cubic foot of packed sand 
 from 165, the weight of a cubic foot of quartz, and divid- 
 ing the difference by 165 degrees. 
 
 The following will serve as an example of proportion- 
 ing materials: Assume voids in packed sand to measure 
 38 per cent., and voids in packed stone to measure 48 
 per cent. Cement paste required per cubic foot of sand, 
 
HOW TO USE THEM 
 
 345 
 
 0.38 and 1-10 equals 0.42 cubic foot, approximately. By 
 trial, 1 cubic foot of loose cement, lightly shaken, makes 
 
 0.85 cubic foot of cement paste, and requires or 
 2 cubic feet of sand, approximately, producing an 
 amount of mortar equal to 0.85 and 2 (1-0.38) equals 
 2.09 cubic feet. Mortar required per cubic foot of stone 
 equals 0.48, and 1-10x0.48 equals 0.528 cubic foot. There- 
 fore 2.09 cubic feet mortar will require equals 
 4 cubic feet of stone, approximately. The proportions 
 are therefore 1 part cement, 2 parts sand, 4 parts stone. 
 Although such a determination is usually considered un- 
 necessary in practical work, it may be of sufficient inter- 
 est to justify giving it. 
 
 For general use the following mixtures are recom- 
 ^ mended : 1 cement, 2 sand, 4 aggregate, for very strong 
 and impervious; 1 cement, 2% sand, 5 aggregate, for 
 ordinary work requiring moderate strength ; 1 cement, 3 
 sand, 6 aggregate, for work where strength is of minor 
 importance. 
 
 Aggregate Containing Fine Material. — In the case of 
 gravel containing sand, or crushed stone from which the 
 small articles have not been removed by screening, the 
 amount of such fine sand or fine stone should be deter- 
 mined and due allowance made for it in proportioning 
 the mortar. 
 
 When mixing an aggregate containing small particles 
 with mortar, and in reality we have a mortar containing 
 a larger proportion of sand than was present before the 
 aggregate was incorporated. It is evident, then, that in 
 such cases the quality of richness of the mortar should 
 depend upon the proportion of fine material in the ag- 
 gregate. 
 
346 
 
 CEMENTS AND CONCKETES 
 
 For example, suppose that 1 cubic foot of gravel con- 
 tains 0.1 cubic foot of sand, and that the voids in gravel 
 with sand screened out measure 40 per cent. For gen- 
 eral purposes this would suggest a 1-2-5 mixture, but 
 since each cubic foot contains 0.1 cubic foot sand; 5 
 cubic feet gravel will contain 0.5 cubic foot sand, and 
 the proportions should be changed to 1 part cement, 1^ 
 parts sand, 5 parts gravel. 
 
 Mechanical Mixers. — It has been demonstrated that 
 concrete can be mixed by machinery as well, if not bet- 
 ter, than by hand. Moreover, if large quantities of con- 
 crete are required, a mechanical mixer introduces marked 
 economy in the cost of construction. None of the various 
 forms of mechanical mixers will be described here, since 
 concrete in small quantities, as would be used on the 
 farm, is more economically mixed by hand. 
 
 Mixing by Hand. — In mixing by hand a platform is 
 constructed as near the work as is practicable, the sand 
 and aggregate being dumped in piles at the side. If the 
 work is to be continuous, this platform should be of suf- 
 ficient size to accommodate two batches, so that one batch 
 can be mixed as the other is being deposited. The ce- 
 ment must be kept under cover and well protected from 
 moisture. A convenient way of measuring the materials 
 is by means of a bottomless box or frame made to hold 
 the exact quantities needed for a batch. 
 
 A very common and satisfactory method of mixing 
 concrete is as follows: First measure the sand and ce- 
 ment required for a batch and mix these into mortar as 
 described on page 5. Spread out this mortar in a thin 
 layer and on top of it spread the aggregate, which has 
 been previously measured and well wetted. The mixing 
 is done by turning with shovels three or more times, as 
 
HOW TO USE THEM 
 
 347 
 
 may be found necessary to produce a thoroughly uni- 
 form mixture, water being added if necessary to give 
 the proper consistency. The mixers, two or four in num- 
 ber, according to the size of the batch, face each other 
 and shovel to right and left, forming two piles, after 
 which the material is turned back into a pile at the cen- 
 tre. By giving the shovel a slight twist, the material is 
 scattered in leaving it and the efficiency of the mixing 
 is much increased. 
 
 Consistency of Concrete. — A dry mixture, from which 
 water can be brought to the surface only by vigorous 
 tamping, is probably the strongest, but for the sake of 
 economy, and to insure a dense concrete well filling the 
 moulds a moderately soft mixture is recommended for 
 ordinary purposes. Where the pieces to be moulded are 
 thin, and where small reinforcing metal rods are placed 
 close together or near the surface, a rather wet mixture 
 may be necessary to insure the moulds being well filled. 
 
 Use of Quick-Setting Cement. — In the manufacture 
 of such articles as pipe, fence posts, and hollow blocks, 
 a rather large proportion of quick-setting cement is 
 sometimes used, the object being to reduce the weight 
 and consequent freight charges by means of a strong 
 mixture, as well as to make the concrete impervious to 
 Avater. The use of a quick-setting cement permits the 
 moulds to be removed sooner than would be possible with 
 a slow-setting cement, thus reducing the number of 
 moulds necessary for a given output. Quick-setting ce- 
 ments are not recommended for such purposes, however, 
 as they are usually inferior to those which set slowly. 
 
 Coloring Cement Work. — In coloring cement work the 
 best results are obtained by the use of mineral pig- 
 ment. The coloring matter,, in proportions depending 
 
348 CEMENTS AND CONCRETES 
 
 upon the desired shade, should be thoroughly mixed with 
 the dry cement before making the mortar. By prepar- 
 ing small specimens of the mortar and noting the color 
 after drying, the proper proportions may be determined. 
 
 For gray or black, use lampblack. 
 
 For yellow or buff, use yellow ochre. 
 
 For brown, use umber. 
 
 For red, use Venetian red. 
 
 For blue, use ultramarine. 
 
 Depositing Concrete. — Concrete should be deposited 
 in layers of from 4 to 8 inches and thoroughly tamped 
 before it begins to harden. The tamping required will 
 depetid upon the consistency of the mixture. If mixed 
 very dry it must be vigorously rammed to produce a 
 dense mass, but as the proportion of water increases less 
 tamping will be found necessary. Concrete should not 
 be dumped in place from a height of more than 4 feet, 
 unless it is again mixed at the bottom. A wooden in- 
 cline may be used for greater heights. Rammers for 
 ordinar;^ concrete work should weigh from 20 to 30 
 pounds and have a face not exceeding 6 inches square. 
 A smaller face than this is often desirable, but a larger 
 one will be less effective in consolidating the mass. In 
 cramped situations special forms must be employed to 
 suit the particular conditions. When a thickness of 
 more than one layer is required, as in foundation work, 
 two or more layers may be Avorked at the same time, each 
 layer slightly in advance of the one next above it and 
 ail being allowed to set together. At the end of a day 
 there is usually left a layer partially completed which 
 must be finished the next day. This layer should not be 
 beveled off, but the last batch of concrete should be 
 tamped behind a vertical board forming a step. 
 
HOW TO USE THEM 
 
 349 
 
 To avoid introducing a plane of weakness where fresh 
 concrete is deposited upon that which has already set, 
 certain precautions have to be observed. The surface of 
 the old work should be clean and wet before fresh ma- 
 terial is put on, a thin coat of neat cement grout being 
 sometimes employed to insure a good bond. The sur- 
 face of the concrete to receive an additional layer must 
 not be finished off smoothly, but should offer a rough 
 surface to bond with the next layer. This may be done 
 by roughing the surface while soft with pick and shovel, 
 or the concrete may be so rammed as to present a rough 
 and uneven surface. Wooden blocks or scantling are 
 sometimes embedded several inches in the work and re- 
 moved before the concrete hardens, thus forming holes 
 or grooves to be filled by the next layer. 
 
 Eetempering, — As stated before, it is important that 
 concrete be tamped in place before it begins to harden, 
 and for this reason it is proper to mix only so much at a 
 time as is required for immediate use. The retempering 
 of concrete which has begun to set is a point over which 
 there is much controversy. From tests made in this 
 laboratory it would appear that such concrete suffers but 
 little loss of strength if thoroughly mixed with sufficient 
 water to restore normal consistence. 
 
 The time required for concrete to set depends upon 
 the character of the cement, upon the amount and tem- 
 perature of the water used in mixing, and upon the 
 temperature of the air. Concrete mixed dry sets more 
 quickly than if mixed wet, and the time required for 
 setting decreases as the temperature of the water rises„ 
 Warm air also hastens the setting. 
 
 Concrete Exposed to Sea-Water, — Portland cement 
 concrete is well adapted for work exposed to sea-water, 
 
350 CEMENTS AND CONCRETES 
 
 but when used for -this purpose it should be mixed with 
 fresh water. The concrete must be practically imper- 
 vious, at least on the surfaces, and to accomplish this 
 purpose the materials should be carefully proportioned 
 and thoroughly mixed. It is also of great importance 
 that the concrete be well compacted by tamping, par- 
 ticularly on exposed surfaces. 
 
 Concrete' Work in Freezing Weather, — Although it is 
 advisable under ordinary conditions to discontinue ce- 
 ment work in freezing weather, Portland cement may be 
 used without serious difficulty by taking a few simple 
 precautions. As little water as possible should be used 
 in mixing, to hasten the setting of the concrete. To 
 prevent freezing, hot water is frequently used in mixing 
 mortar or concrete, and'with the same object in view salt 
 is added in amounts depending upon the degree of cold. 
 A common practice is to add 1 pound of salt to 18 gal- 
 lons of water, with the addition of 1 oz. of salt for each 
 degree below 32° F. Either of the above methods will 
 give good results, but it should be remembered that the 
 addition of salt often produces efflorescence. It seems 
 to be a fairly well-established fact that concrete de- 
 posited in freezing weather will ultimately develop full 
 strength, showing no injury due to the low temperature. 
 
 Rubble Concrete. — In massive concrete work consider- 
 able economy may often be introduced by the use of 
 large stones in the body of the work, but only in heavy 
 foundations, retaining walls, and similar structures 
 should this form of construction be permitted. In plac- 
 ing these large stones in the work the greatest care must 
 be exercised to insure each being well bedded, and the 
 concrete must be thoroughly tamped around them. Each 
 
HOW TO USE THEM 
 
 351 
 
 stone should be at least 4 inches from its neighbor and 
 an equal distance from the face of the work. 
 
 To Face Concrete. — A coating of mortar one-half 
 inch in thickness is frequently placed next the form to 
 prevent the stone or gravel from showing and to give 
 a smooth and impervious surface. If in preparing this 
 mortar finely crushed stone is used instead of sand, th^^ 
 
 •Sheet-metal plate used in facing concrete* 
 NO, 6. 
 
 work will more nearly resemble natural stone. A 
 common method employed in facing concrete is to pro- 
 vide a piece of thin sheet metal of convenient length 
 and about 8 to 10 inches wide. To this pieces of angle 
 iron are riveted, so that when placed next to the mould 
 a narrow space is formed in which the cement mortar is 
 placed after the concrete has been deposited behind it. 
 (No. 6.) The metal plate is then withdrawn and the 
 
352 CEMENTS AND CONCRETES 
 
 concrete well tamped. The concrete and facing mor- 
 tar must be put in at the same time so that they will 
 set together. If the concrete is fairly rich, a smooth 
 surface can usually be produced without a facing of 
 mortar by working a spade up and down between the 
 concrete and inner face of the mould, thus forcing the 
 larger pieces of the aggregate back from the surface. 
 
 Wood for Forms. — Lumber used in making forms for 
 concrete should be dressed on one side and both edges. 
 The expansion and distortion of the wood due to the 
 absorption of water from the concrete frequently make 
 it difficult to produce an even surface on the work, and 
 unless the forms are accurately fitted together more or 
 less water will find its way out through the cracks, 
 carrying some of the cement with it. A method some- 
 times adopted to minimize the effect of expansion is to 
 bevel one edge of each board, allowing this edge to 
 crush against the square edge of the adjacent board 
 when expansion takes place. In the case of a wooden 
 core or inside mold, expansion must always be taken intc 
 consideration, for if neglected it may cause cracks or 
 complete rupture of the concrete. Sharp edges in con* 
 Crete are easily chipped and should be avoided by plac- 
 ing triangular strips to the corners of moulds. To pre- 
 vent cement from sticking to the forms they may be 
 given a coating of soft soap or be lined with paper. 
 I'his greatly facilitates their removal and enables them 
 to be used again with but little scraping. A wire brush 
 answers best for cleaning the forms. 
 
 Concrete Sidewalks. — A useful and comparatively 
 simple application of concrete is in the construction of 
 sidewalks, for which purpose it has been used with 
 marked success for a number of years. 
 
HOW TO USE THEM 
 
 353 
 
 Excavation and Preparation of Subgrade. — The 
 ground is excavated to subgrade and well consolidated 
 by ramming to prepare it for the subfoundation of 
 stone, gravel or cinders. The depth of excavation will 
 depend upon the climate and nature of the ground, 
 being deeper in localities where heavy frosts occur or 
 where the ground is soft than in climates where there 
 are no frosts. In the former case the excavation should 
 be carried to a depth of 12 inches, whereas in the latter 
 from 4 to 6 inches will be sufficient. No roots of trees 
 should be left above the subgrade. 
 
 The Subfoundation. — The foundation consists of a 
 layer of loose material, such as broken stone, gravel, 
 or cinders, spread over the subgrade and well tamped to 
 secure a firm base for the main foundation of concrete 
 which is placed on top. It is most important that the 
 subfoundation be well drained to prevent the accumula- 
 tion of water, which, upon freezing, would lift and crack 
 the walk. For this purpose it is well to provide drain 
 tile at suitable points to carry off any water which may 
 collect under the concrete. An average thickness for. 
 subfoundation is 4 to 6 inches, although in warm cli- 
 mates, if the ground is firm and wells drained, the sub- 
 foundation may only be 2 to 3 inches thick or omitted 
 altogether. 
 
 The Foundation, — The foundation consists of a layer 
 of concrete deposited on the subfoundation and carry- 
 ing a surface layer or wearing coat of cement mortar. If 
 the ground is firm and the subfoundation well rammed 
 in place and properly drained, great strength will not be 
 required of the concrete, which may, in such cases, be 
 mixed in about the proportions 1-3-6, and a depth of only 
 3 to 4 inches will be required. Portland cement should 
 
354 CEMENTS AND CONCEETES 
 
 be used and stone or gravel under 1 inch in size, the con- 
 crete being mixed of medium consistency, so that 
 moisture will show on the surface without excessive 
 tamping. 
 
 The Top Dressing or Wearing Surface. — To give a 
 neat appearance to the finished walk, a top dressing of 
 cement mortar is spread over the concrete, well worked 
 in, and ^brought to a perfectly smooth surface with 
 straightedge and float. This mortar should be mixed 
 in the proportion 1 part cement to 2 parts sand, sharp 
 coarse sand or screenings below one-fourth inch of some 
 hard, tough rock being used. The practice of making 
 the concrete of natural cement and, the wearing surface 
 of Portland is not to be commended, owing to a tendency 
 for the two to separate. 
 
 Details of Construction. — A cord stretched between 
 stakes w^ll serve as a guide in excavating, after which 
 the bottom of the trench is well consolidated by ram- 
 ming; any loose material below subgrade is then spread 
 over the bottom of the trench to the desired thickness 
 and thoroughly compacted. Next, stakes are driven 
 along the sides of the walk; spaced 4 to 6 feet apart, 
 and their tops made even with the finished surface of 
 the walk, which should have a transverse slope 
 of one-fourth inch to the foot for drainage. Wooden 
 strips at least inches thick and of a suitable depth 
 are nailed to these stakes to serve as a mould to concrete. 
 By carefully adjusting these strips to the exact height of 
 the stakes they may be used as guides for the straight- 
 edge in levelling off the concrete and wearing surface. 
 The subfoundation is well sprinkled to receive the con- 
 crete, which is deposited in the usual manner, well 
 tamped behind a board set vertically across the trench, 
 
HOW TO USE THEM 
 
 355 
 
 and levelled off with a straightedge as shown in Fig. 7, 
 leaving one-half to 1 inch for the wearing surface. 
 Three-eighths inch sand joints are provided at intervals 
 of 6 to 8 feet to prevent expansion cracks, or, in case of 
 settlement, to confine the cracks to these joints. This is 
 dene either by depositing the concrete in sections, or by 
 dividing it into such sections with a spade when soft and 
 filling the joints with sand. The location of each joint 
 is marked on a w^ooden frame for future reference. 
 
 NO. 7. 
 
 Care must be exercised to prevent sand or any other 
 material from being dropped on the concrete, and thus 
 preventing a proper union with the wearing surface. No 
 section should be left partially completed to be finished 
 with the next batch or left until the next day. Any con- 
 crete left after the completion of a section should be 
 mixed w^ith the next batch. 
 
 It is of the utmost importance to follow up closely the 
 concrete work with the top dressing in order that the 
 
S56 CEMENTS AND CONCEETES 
 
 two may set together. This top dressing should be 
 worked well over the concrete with a trowel, and levelled 
 with a straightedge (No. 7) to secure an even surface. 
 Upon the thoroughness of this operation often depends 
 the success or failure of the walk, since a good bond be- 
 tween the wearing surface and concrete base is absolute- 
 ly essential. The mortar should be mixed rather stiff. 
 As soon as the film of water begins to leave the surface, 
 a wooden float is used, followed up by a plasterer's 
 trowel, the operation being similar to that of plastering 
 a wall. The floating, though necessary to give a smooth 
 surface, will, if continued too long, bring a thin layer of 
 neat cement to the surface and probably cause the walk 
 to crack. 
 
 Jointer used in dividing walk 
 into sections. 
 
 NO. 8. 
 
 The surface is now divided into sections by cutting en- . 
 tirely through, exactly over the joints in the concrete. 
 This is done with a trowel guided by a straightedge, 
 after which the edges are rounded oft* with a special tool 
 called a jointer, having a thin shallow tongue (No. 8). 
 These sections may be subdivided in any manner desired 
 for the sake of appearance. 
 
 A special tool called an edger (No. 9) is run round the 
 outside of the walk next to the mould, giving it a neat 
 rounded edge. A toothed roller (No. 10) having small 
 
HOW TO USE THEM 357 
 
 projections on its face is frequently used to produce 
 slight indentations on the surface, adding somewhat to 
 
 Tool used in rounding edges. 
 NO. 9. 
 
 the appearance of the walk. The completed work must 
 be protected from the sun and kept moist by sprinkling 
 
 'Roller used in finishing surface 
 NO. 10. 
 
 for several days. In freezing weather the same precau- 
 tions should be taken as in other classes of concrete 
 work. 
 
358 CEMENTS AND CONCEETES 
 
 Concrete Basement Floors, — Basement floors in dwell- 
 ing houses as a rule require only a moderate degree of 
 strength, although in cases of very wet basements, where 
 water pressure from beneath has to be resisted, greater 
 strength is required than would otherwise be necessary. 
 The subfoundation should be well drained, sometimes re- 
 quiring the use of tile for carrying off the water. The 
 rules given for constructing concrete sidewalks apply 
 equally well to basement floors. The thickness of the 
 concrete foundation is usually from 3 to 5 inches, ac- 
 cording to the strength desired, and for average work a 
 1-3-6 mixture is sufficiently rich. Expansion joints are 
 frequently omitted, since the temperature variation is 
 less than in outside work, but since this omission fre- 
 quently gives rise to unsightly cracks, their use is recom- 
 mended in all cases. It will usually be sufficient to 
 divide a room of moderate size into four equal sections, 
 separated by % inch sand joints. The floor should be 
 given a slight slope toward the center or one corner, with 
 provision at the lowest point for carrying off any water 
 that may accumulate. 
 
 Concrete Stable Floors and Driveivays, — Concrete 
 stable floors and driveways are constructed in the same 
 general way as basement floors and sidewalks, but with 
 a thicker foundation, on account of the greater strength 
 required. The foundation may well be 6 inches thick, 
 .with a 10 inch wearing surface. An objection often 
 sometimes raised against concrete driveways is that they 
 become slippery when wet; but this fault is in a great 
 measure overcome by dividing the wearing surface into 
 small squares about 4 inches on the side, by means of tri- 
 angular grooves % of an inch deep. This gives a very 
 
HOW TO USE THEM 
 
 359 
 
 neat appearance and furnishes a good foothold for 
 horses. 
 
 Concrete Steps. — Concrete may be advantageously 
 used in the construction of steps, particularly in damp 
 places, such as areaways and cellars of houses, and in 
 the open, where the ground is terraced, concrete steps 
 and walks can be made exceedingly attractive. Where 
 the ground is firm it may be cut away as nearly as pos- 
 sible in the form of steps, with each step left two or 
 three inches below its finished level. The steps are 
 formed, beginning at the top, by depositing the con- 
 
 Keinforced concrete steps. 
 
 NO. 11. 
 
 Crete behind vertical boards so placed as to give the nec- 
 essary thickness to the risers and projecting high enough 
 to serve as a guide in leveling off the tread. Such steps 
 may be reinforced where greater strength is desired or 
 where there is danger of cracking, due to the settlement 
 of the ground. 
 
 Where the nature of the ground will not admit of its 
 being cut away in the form of steps, the risers are 
 
360 CEMENTS AND CONCRETES 
 
 molded between two vertical forms. The front one may 
 be a smooth board, but the other should be a piece of 
 thin sheet metal, which is more easily removed after the 
 earth has been tamped in behind i-t. A simple method 
 of reinforcing steps is to place a % inch steel rod in each 
 corner, and thread these with i/4 inch rods bent to the 
 shape of the steps, as shown in No. 11, the latter being 
 placed about 2 feet apart. For this class of work a rich 
 Portland cement concrete is recommended, with the use 
 of stone or gravel under % inch in size. Steps may be 
 given a ^ inch wearing surface of cement mortar mixed 
 in the proportion of 1 part cement to 2 parts sand. This 
 system, as well as many others, is well adapted for stair- 
 ways in houses. 
 
 Reinforced Concrete Fence Posts. — Comparison of dif- 
 ferent Post Materials: There is a constantly increasing 
 demand for some form of fence posts which is not sub- 
 ject to decay. The life of wooden posts is very limited, 
 and the scarcity of suitable timber in many localities 
 has made it imperative to find a substitute. A fence 
 post, to prove thoroughly satisfactory,' must fulfil three 
 conditions: (1) It must be obtainable cost; (2) it must 
 possess sufficient strength to meet the demands of gen- 
 eral farm use; (3) it must not be subject to decay, and 
 must be able to withstand successfully the effects of 
 water, frost and fire. Although iron posts of various 
 designs are frequently used for ornamental purposes, 
 their adoption for general farm use is prohibited by their 
 excessive cost. Then, too, iron posts exposed to the 
 weather are subject to corrosion, to prevent which neces- 
 sitates repainting from time to time, and this item will 
 entail considerable expense in cases where a large nura- 
 ber of posts are to be used, 
 
HOW TO USE THEM 361 
 
 At the present time the material which seems most 
 nearly to meet these requirements is i^einforeed con- 
 crete. The idea of constructing fence posts of concrete 
 reinforced with iron or steel is by no means a new one, 
 but, on the contrary, such posts have been experimented 
 with for years, and a great number of patents have been 
 issued covering many of the possible forms of reinforce- 
 ment. It is frequently stated that a reinforced con- 
 crete post can be made and put in the ground for the 
 same price as a wooden post. Of course this will de- 
 pend in any locality upon the relative value of wood and 
 the various materials which go to make up the concrete 
 post, but in the great majority of cases wood will prove 
 the cheaper material in regard to first cost. On the 
 other hand, a concrete post will last indefinitely, its 
 strength increasing with age, whereas the wooden post 
 must be replaced at short intervals, probably making it 
 more expensive in the long run. 
 
 In regard to strength, it must be borne in mind that 
 it is not practicable to make concrete fence posts as 
 strong as wooden posts of the same size j but since wooden 
 posts, as a rule, are many times stronger than is neces- 
 sary, this difference in strength should not condemn the 
 use of reinforced concrete for this purpose. Moreover, 
 strength in many cases is of little importance, the fence 
 being used only as a dividing line, and in such cases 
 small concrete posts provide ample strength and present 
 a very uniform and neat appearance. In any case, to 
 enable concrete posts to withstand the loads they are 
 called upon to carry, sufficient strength may be secured 
 by means of reinforcement, and where great strength is 
 required this may be obtained by using a larger post 
 with a greater proportion of metal and well braced, as 
 
362 CEMENTS AND CONCRETES 
 
 is usual in such cases. In point of durability, concrete 
 is unsurpassed by any material of construction. It offers 
 a perfect protection to the metal reinforcement and is 
 not itself affected by exposure, so that a post constructed 
 of concrete reinforced with steel will last indefinitely and 
 require no attention in the way of repairs. 
 
 Reinforcement. — No form of wooden reinforcement, 
 either on the surface or within the post, can be recom- 
 mended. If on the surface^ the wood will soon decay, 
 and if a wooden core is used it will^ in all probability, 
 swell by the absorption of moisture and crack the post. 
 The use of galvanized wire is sometimes advocated, but 
 if the post is properly constructed and a good concrete 
 used, this precaution against rust will be unnecessary, 
 since it has been fully demonstrated by repeated tests 
 that concrete protects steel perfectly from rust. If 
 plain, smooth wire or rods are used for reinforcement 
 they should be bent over at the ends or looped to pre- 
 vent slipping in the concrete. Twisted fence wire may 
 usually be obtained at a reasonable cost and is very well 
 suited for this purpose. Barbed wire has been proposed 
 and is sometimes used, although the barbs make it ex- 
 tremely difficult to handle. For the sake of economy the 
 smallest amount of metal consistent with the desired 
 strength must be used, and this requirement makes it 
 necessary to place the reinforcement near the surface, 
 where its strength is utilized to greatest advantage, with 
 only enough concrete on the outside to form a protective 
 covering. A reinforcing member in each corner of the 
 post is probably the most efficient arrangement. 
 
 Concrete for Fence Posts. — The concrete should be 
 mixed with Portland cement in about the proportions 
 1-2^-5, broken stone or gravel under % inch being used. 
 
HOW TO USE THEM 363 
 
 In cases where the aggregate contains pieces smaller 
 than 14 inch, less sand may be used, and in some cases 
 it may be omitted altogether. A mixture of medium con- 
 sistency is recommended on the ground that it fills the 
 molds, better and with less tamping than if mixed quite 
 dry. 
 
 Molds for Fence Posts. — Economy points to the use 
 of a tapering post, which, fortunately, offers no diffi- 
 culties in the way of molding. All things considered, 
 
 Wooden jnoldLfor making fence posts with four tapering sides. 
 NO. 12. 
 
 wooden molds will be found most suitable. They can 
 easily and quickly be made in any desired form and size. 
 Posts may be molded either in a vertical or horizontal 
 position, the latter being the simpler and better method. 
 If molded vertically a wet mixture is necessary, requir- 
 ing a longer time to set, with the consequent delay in 
 removing the molds. No. 12 shows a simple mold, which 
 has been used with satisfactory results in this laboratory. 
 
364 CEMENTS AND CONCRETES 
 
 This mold has a capacity of four posts, but larger molds 
 could easily be made on the same principle. It consists 
 of two end pieces, (a) carrying lugs, (b) between which 
 are inserted strips (c). The several parts are held to- 
 gether with hooks and eyes, as shown in No. 12. To pre- 
 vent any bulging of the side strips they are braced, as 
 illustrated. Dressed lumber at least 1 inch thick, and 
 preferably 1% inches, should be used. In No. 12 the 
 
 .-Wooden mold for making fence posts with two tapering sides. 
 NO. 13. 
 
 post measures 6 by 6 inches at the bottom, 6 by 3 at the 
 top, and 7 feet in length, having two parallel sides. If 
 it is desired to have the posts square at both ends the 
 mold must be arranged as in No. 13. This latter form 
 of post is not as strong as the former, but requires less 
 concrete in its construction. Great care in tamping is 
 necessary to insure the corners of the mold being well 
 
HOW TO USE THEM 
 
 365 
 
 filled, and if this detail is not carefully watched, the 
 metal, being exposed in places, will be subject to rust. 
 
 Attaching Fence Wires to Posts. — Various devices have 
 been suggested for attaching fence wires to the posts, the 
 object of each being to secure a simple and permanent 
 fastener or one admitting of easy renewal at any time. 
 Probably nothing will answer the purpose better than a 
 long staple or bent wire well embedded in the concrete, 
 being twisted or bent at the end to prevent extraction. 
 Galvanized metal must be used for fasteners, since they 
 
 are not protected by the concrete. A piece of small flex- 
 ible wire, about two inches in length, threading the staplf 
 and twisted several times with a pair of pliers, holds the 
 line wire in position. (No. 14.) 
 
 Molding and Curing Posts. — For the proper method of 
 mixing concrete see previous pages. It is recommended 
 that only so much concrete be mixed at one time as can 
 be used before it begins to harden ; but if an unavoidable 
 delay prevents the posts being molded until after the 
 
 •Detail showing method ot 
 taching wire to post. 
 
 NO. 14. 
 
366 CEMENTS AND CONCRETES 
 
 concrete has begun to set, it is thought that a thorough 
 regauging with sufficient water to restore normal con- 
 sistency will prevent any appreciable loss of strength, 
 though the concrete may have been standing one or two 
 hours. In using a mold similar to those illustrated in 
 Nos. 12 and 13 it is necessary to provide a perfectly 
 smooth and even platform of a size depending upon the 
 number of posts to be molded. A cement floor if accessi- 
 ble may be used to advantage. The molds when in place 
 are given a thin coating of soft soap, the platform or 
 cement floor, serving as bottom of mold, being treated in 
 the same way. About 1% inches is spread evenly over 
 the bottom and carefully tamped, so as to reduce it to a 
 thickness of about 1 inch. A piece of board cut as in 
 No. 12 will be found useful in leveling off the concrete to 
 the desired thickness before tamping. On top of this 
 layer two reinforcing members are placed about 1 inch 
 from the sides of the mold. The molds are then filled 
 and tamped in thin layers to the level of the other two 
 reinforcing members, the fasteners for fence wires being 
 inserted during the operation. These reinforcing mem- 
 bers are adjusted as were the first two, and the remain- 
 ing 1 inch of concrete tamped and leveled off, thus com- 
 pleting the post so far as molding is concerned. To avoid 
 sharp edges, which are easily chipped, triangular strips 
 may be placed in the bottom of mold along the sides, and 
 when the molds have been filled and tamped, similar 
 strips may be inserted on top. The top edges may be 
 beveled with a trowel or by running an edging tool hav- 
 ing a triangular projection on its bottom along the edges. 
 Such a tool is shown in No. 15, and can easily be made 
 of wood or metal. It is not necessary to carry the bevel 
 below the ground line. 
 
HOW TO USE THEM 
 
 867 
 
 The ends and sides of the mold may be removed after 
 twenty-four hours, but the posts should not be handled 
 for at least one week, during which time they must be 
 well sprinkled several times daily and protected from sun 
 and wind. The intermediate strips may be carefully 
 withdrawn at the end of two or three days, but it is bet- - 
 ter to leave them in place until the posts are removed. 
 Although a post may be hard and apparently strong 
 when one week old^ it will not attain its full strength in 
 that length of time, and must be handled with the utmost 
 care to prevent injury. Carelessness in handling green 
 posts frequently results in the formation of fine cracks, 
 which though unnoticed at the time, give evidence of 
 their presence later in the failure of the posts. 
 
 Tool used for beveling edges of 
 posts. 
 
 NO. 15. 
 
 Posts ishould be allowed to cure for at least sixty days 
 before being placed in the ground, and for this purpose 
 it is recommended that when moved from the molding 
 platform they be placed upon a smooth bed of moist sand 
 and protected from the sun until thoroughly cured. Dur- 
 ing this period they should receive a thorough drench- 
 ing at least once a day. 
 
368 
 
 CEMENTS AND CONCEETES 
 
 The lif 3 of the molds will depend upon the care with 
 which they are handled. A coating of mineral oil or 
 shellac may be used instead of soap to prevent the cement 
 from sticking to the forms. As soon as the molds are 
 \removed they should be cleaned with a wire brush before 
 [being used again. 
 
 The cost of reinforced concrete fence posts depends 
 in each case upon the cost of labor and materials, and 
 must necessarily vary in different localities. An esti- 
 mate in any particular case can be made as follows: One 
 cubic yard of concrete will make twenty posts measuring 
 6 inches by 6 inches at the bottom, 6 inches by 3 inches 
 at the top, and 7 feet long, and if mixed in the propor- 
 
 tions 1-2^-5, requires approximately : 
 
 1.16 barrels of cement, at $2 $2.32 
 
 0.44 cubic yard of sand, at 75 cts 33 
 
 0.88 cubic yard of gravel, at 75 cts 66 
 
 Materials for 1 cubic yard cement $3.21 
 
 Concrete for one post 17 
 
 28 feet of 0.16 inch steel wire, at 3 cts a pound 06 
 
 Total cost of concrete and metal for 1 post 23 
 
 To this must be added the cost of mixing concrete, 
 molding and handling posts, and the costs of molds, an 
 addition which should not in any case exceed 7 cents, 
 making a total of 30 cents per post. 
 
 Concrete Building Blocks. — Concrete building blocks, 
 or cement blocks, as they are frequently called, are more 
 extensively used now than ever before. These blocks 
 are molded hollow primarily to reduce their cost, but 
 ihis hollow construction serves other useful purposes at 
 the same time. The fundamental principles governing 
 
HOW TO USE THEM 
 
 369 
 
 ordinary concrete work, so far as proportioning and 
 mixing materials is concerned, apply equally well to the 
 manufacture of building blocks, and it should be borne 
 in mind that strength and durability can not be obtained 
 by the use of any machine unless the cement, sand, and 
 aggregate are of good quality, properly proportioned 
 and well mixed. The aggregate for blocks of ordinary 
 size should be crushed stone or gravel not larger than 
 l^ inch. One of the chief causes of complaint against 
 the concrete building block is its porosity, but this defect 
 is in a great measure due to the fact that in an endeavor 
 to economize too little cement is frequently used. It is 
 not unusual to give the blocks a facing of cement mor- 
 tar consisting of about 2 parts sand to 1 of cement, while 
 the body of the block is composed of a concrete of suffi- 
 cient strength, though not impervious. This outside 
 layer of mortar adds practically nothing to the strength 
 of the block, and is used simply to give a uniform sur- 
 face and to render the face of the wall more clearly im- 
 pervious to water. 
 
 It would not be practicable as a rule to attempt the 
 manufacture of concrete blocks without one of the many 
 forms of molding machines designed for the purpose, noi 
 would it be economical to purchase such a machine un- 
 less a sufficient number of blocks were required to ju;stify 
 such an outlay. Blocks in almost any desired shape and 
 size, with either plain or ornamental faces, may be ob- 
 tained on the market^ and in the great majority of cases 
 it is best to buy them from some reliable firm. Among 
 the advantages claimed for hollow concrete block con- 
 struction may be mentioned the following : 
 
 (1) Hollow block conistruction introduces a saving of 
 material over brick or stone masonry. 
 
370 CEMENTS AND CONCRETES 
 
 (2) The cost of laying concrete blocks is less than for 
 brick work. This is due to the fact that the blocks, being 
 larger/ require a much smaller number of joints and 
 less mortar, and, being hollow, are of less weight than 
 solid brick work. 
 
 (3) A wall constructed of good concrete blocks is as 
 strong or stronger than a brick wall of equal thickness. 
 
 (4) Concrete blocks, being easily molded to any de- 
 sired form, will prove to be a far more economical build- 
 ing material than stone, which has to be dressed to 
 shape. 
 
 (5) Experience has proved concrete to be a most cx- 
 <iellent fire resisting material. 
 
 (6) Concrete blocks, being hollow, tend to prevent 
 sudden changes of temperature within a house, making 
 it cool in summer and easily heated in winter. 
 
 (7) The hollow spaces provide an easy- means for 
 running pipes and electric wires. These spaces may also 
 be used wholly or in part for heating and ventilating 
 flues. 
 
 Tests of Concrete Fence Posts. — In the summer of 
 1904 a number of reinforced concrete fence posts were 
 made for experimental purposes, with a view to deter- 
 mining their adaptability for general use. These posts 
 were made both with and without reinforcement^ and 
 tested at the age of 90 days. The reinforcement, rang- 
 ing from 0.27 per cent, to 1.13 per cent., consisted of 
 four round steel rods, one in each corner of post about 
 1 inch from surface, the posts having a uniform cross- 
 section of 6 by 6 inches. The posts were molded in a 
 horizontal position, as this was found by trial to be more 
 satisfactory than molding them vertically. 
 
HOW TO USE THEM 
 
 371 
 
 The concrete was mixed moderately soft, crushed stone 
 between 1 inch and l^ inch and gravel under % inch 
 being used as aggregate. River sand, fairly clean and 
 sharp, was employed with Portland cement. The posts 
 were tested as beams, supported at both ends and loaded 
 at the centre, with spans varying from 4 feet to 5 feet 6 
 inches. An attempt was made to prevent slipping by 
 providing the reinforcing rods with collars and set 
 screws at the ends, but in every case, with but two ex- 
 ceptions, the rods slipped under a comparatively light 
 load, thus showing the necessity for some form of me- 
 chanical bond. As would be expected, those posts which 
 were not reinforced possessed very little strength. 
 
 A series of tests was made with sheet-iron reinforce- 
 ment, in the form of round and square pipes, embedded 
 in the posts, but these posts, though developing consid- 
 erable strength, proved less economical than those rein- 
 forced with plain rods^ and at the same time were less 
 simple in construction. The results of these tests, as re- 
 corded in Table I., do not properly represent the strength 
 of similar posts in which some form of mechanical bond 
 is provided to develop the full strength of the reinforce- 
 ment. 
 
 Method of testing 
 posts under static loads. 
 
372 CEMENTS AND CONCEETES 
 
 Equivalent 
 Maximum 
 Load on 
 4-foot 
 
 1 h^^^m^^^nn^M^^^^ 
 
 Equivalent 
 Load on 
 
 4-foot Can- 
 tilever at 
 
 1 « 
 
 Maximum 
 Load. 
 
 
 Load 
 at First 
 Crack. 
 
 
 1 
 
 
 
 
 
 
 mBmBmmmmmm 
 
 Per Cent 
 Rein'force- 
 
 I : : : : : ifiRSSRSSSSSSgggggggggSSSS 
 
 I 
 
 
 6 
 
 
HOW TO USE THEM 373 
 
 Equivalent 
 Maximum 
 Load on 
 4-foot 
 
 I III m iSi 
 
 Equivalent 
 Load on 
 
 4-foot Can- 
 tilever at 
 
 ^ fi^sliSiiiiiiiiiiigii II : iie iil 
 
 Maximum 
 Load. 
 
 Poimds. 
 3,545 
 4,200 
 3,575 
 5, 150 
 4,300 
 4,240 
 2,600 
 3,160 
 3,345 
 3,840 
 2,600 
 3,820 
 5,080 
 3,100 
 4,900 
 4,460 
 2,900 
 2,320 
 3,270 
 4,300 
 
 4,000 
 4,000 
 4,660 
 
 6,320 
 5,880 
 6,040 
 
 2,450 
 2,660 
 2,400 
 
 Load 
 at First 
 Crack. 
 
 11 i III ill 
 
 
 
 i 
 
 
 
 
 
 |°o|oo|oooo|00oo^ooo ooo ooo goo 
 
 xture. 
 
 i0^iOut>iOiOut)iO^»OiOiCiOiCiO>0>OiOut)iC 'O^kO iCiO»0 "tiiOiO 
 
 (N <^^ (^^ w CO CO c<i c<i c<i c<i <n c<J c<i C4 (N c^chch 
 
 
 
 Per Cent 
 of 
 
 Reinforce- 
 ment. 
 
 ^^M^^^^:^^^^.^^^^^^^^^ 222 
 
 Kind of Reinforcement. 
 
 Plain Steel Rods 
 
 do 
 
 do 
 
 do 
 
 do 
 
 do 
 
 do 
 
 do 
 
 do 
 
 do 
 
 do 
 
 do 
 
 do 
 
 do 
 
 do 
 
 do 
 
 do 
 
 do 
 
 do 
 
 Pipe 5 inches diameter, 1-40 
 
 inch thick 
 
 do 
 
 do 
 
 □ 5 by 5 inches, 1-40 inch 
 
 thick 
 
 do 
 
 do 
 
 X 5 by 5 inches, 1-40 inch 
 
 thick 
 
 do 
 
 do 
 
374 CEMENTS AND CONCRETES 
 
 In order to obtain more data on the subject, this in- 
 vestigation has been supplemented by a second series of 
 tests, the results of which form the subject matter for 
 the sections on concrete fence posts and are expressed 
 numerically in Table II. 
 
 In these tests it was decided to make the posts taper- 
 ing in order to economize material and reduce their 
 weight. For the concrete, Portland cement, river sand, 
 and gravel were used in the proportion 1-21/2-5, meas- 
 ured by volume, the gravel being screened below I/2 inch. 
 Sufficient water was used in mixing to produce a plastic 
 mass^ requiring only a moderate degree of tamping to 
 bring water to the surface. The posts were molded and 
 kept under wet burlap for four weeks, and tested at the 
 end of sixty days. The reinforcing members were placed 
 in the corners of the posts about 1 inch from the surface, 
 being looped and bent, as indicated in Table II. These 
 posts were not designed with a view to developing the 
 ultimate compressive strength of the concrete, but where 
 greater strength is necessary it may be obtained at small 
 expense by increasing the percentage of reinforcement. 
 It is important that fairly rich concrete should be used 
 in all cases to enable the posts to stand exposure and to 
 prevent chipping. 
 
 All of these posts measured 6 by 6 inches at the 
 bottom and 6 by 3 inches at the top, except Nos. 29, 
 30, 31, 32, 33, and 34, which were 6 by 6 at the 
 bottom and 3 by 3 at the top. It will be noticed that the 
 saving in concrete introduced in the construction of these 
 posts is accompanied by a marked decrease in strength 
 as compared with the other posts similarly reinforced. 
 It would also appear that the twisted wire has a slight 
 
HOW TO USE THEM 
 
 375 
 
 Table II. Showing the Strength op Reinforced 
 Concrete Fence Posts. 
 
 Kind of rein- 
 forcement. 
 
 Total sectional area of reinforcement. 
 In square inches. 
 
 Load at first crack. In Pounds. 
 
 Maximum load. In Pounds. 
 
 Equivalent load on 4-foot cantilever 
 at first crack. In Pounds. 
 
 Equivalent maximum load on 4-foot 
 cantilever. In Pounds. 
 
 Drawn steel rods 
 
 0.08 
 
 800 
 
 1120 
 
 218 
 
 306 
 
 
 .08 
 
 820 
 
 1145 
 
 224 
 
 313 
 
 
 .08 
 
 640 
 
 1080 
 
 175 
 
 295 
 
 
 .08 
 
 795 
 
 1040 
 
 217 
 
 284 
 
 
 .08 
 
 940 
 
 1170 
 
 257 
 
 319 
 
 
 .08 
 
 740 
 
 1075 
 
 202 
 
 293 
 
 
 .19 
 
 1140 
 
 1280 
 
 311 
 
 349 
 
 
 .19 
 
 1170 
 
 1885 
 
 319 
 
 515 
 
 do 
 
 .19 
 
 1020 
 
 1950 
 
 278 
 
 532 
 
 do 
 
 .19 
 
 760 
 
 1945 
 
 207 
 
 531 
 
 do 
 
 .19 
 
 820 
 
 1925 
 
 224 
 
 526 
 
 Twisted fence wire 
 
 .06 
 
 825 
 
 935 
 
 225 
 
 255 
 
 
 .06 
 
 755 
 
 905 
 
 206 
 
 247 
 
 
 .06 
 
 800 
 
 940 
 
 218 
 
 257 
 
 
 .06 
 
 815 
 
 935 
 
 222 
 
 255 
 
 
 .06 
 
 770 
 
 980 
 
 210 
 
 268 
 
 
 .06 
 
 780 
 
 975 
 
 213 
 
 266 
 
 
 .13 
 
 1550 
 
 1920 
 
 423 
 
 524 
 
 
 .13 
 
 1275 
 
 1670 
 
 348 
 
 456 
 
 
 .13 
 
 1200 
 
 1830 
 
 328 
 
 500 
 
 
 .13 
 
 1500 
 
 1955 
 
 410 
 
 534 
 
 Barbed wire 
 
 .06 
 
 980 
 
 980 
 
 268 
 
 268 
 
 do 
 
 .06 
 
 820 
 
 820 
 
 224 
 
 224 
 
 do 
 
 .06 
 
 590 
 
 740 
 
 161 
 
 202 
 
 do 
 
 .06 
 
 745 
 
 745 
 
 203 
 
 203 
 
 do 
 
 .06 
 
 590 
 
 590 
 
 161 
 
 161 
 
 do 
 
 .06 
 
 550 
 
 640 
 
 150 
 
 175 
 
 do 
 
 .06 
 
 560 
 
 635 
 
 153 
 
 173 
 
 do 
 
 .06 
 
 480 
 
 530 
 
 131 
 
 145 
 
 do 
 
 .13 
 
 680 
 
 1040 
 
 186 
 
 284 
 
 do 
 
 .13 
 
 840 
 
 1010 
 
 229 
 
 276 
 
 do 
 
 .13 
 
 1280 
 
 1515 
 
 349 
 
 414 
 
 do 
 
 .13 
 
 800 
 
 1375 
 
 218 
 
 375 
 
 Drawn steel rods 
 
 .08 
 
 Tested by 
 
 mpact 
 
 do 
 
 .19 
 
 
 do 
 
 
 
 do 
 
 .19 
 
 fin 
 
 Twisted fence wire 
 
 .06 
 
 
 do... 
 
 
 
 do 
 
 .06 
 
 
 fin 
 
 
 
 
 
 Form of reinforcement. 
 
376 CEMENTS AND CONCRETES 
 
 advantage over the barbed wire as a reinforcing material, 
 particularly when two wires are used in each corner of 
 the post. 
 
 As stated before, it is impracticable to make a rein- 
 forced concrete fence post as strong as a wooden post of 
 the same size, and this is more especially true if the post 
 
 has to withstand the force of a sudden blow or impact. 
 In order to study the behavior of these posts under im- 
 pact, a number of them were braced, as illustrated in 
 No. 17, and subjected to the blow of a 50-pound bag of 
 gravel, suspended from above by a 9-foot rope. The 
 first blow was delivered by deflecting the bag so as to 
 give it a vertical drop of 1 foot, and for each successive 
 
HOW TO USE THEM 
 
 377 
 
 blow the drop was increased 1 foot. None of the posts 
 showed any signs of failure under the first blow. Posts 
 Nos. 14 and 20 cracked under the second blow, and failed 
 under the third. Post No. 6 cracked under the second 
 blow, which cracked open under the third blow, causing 
 a momentary deflection of 5 inches. Posts Nos. 7 and 8 
 each developed a crack under the second blow, but 
 showed no further signs of weakness after the fifth blow. 
 
 Second method of testing 
 posts by impact. 
 
 NO. 18. 
 
 other than a slight opening of the initial crack. In each 
 case the only crack developed was at point A. Posts 6, 
 7, and 8, which cracked but did not fail under the im- 
 pact test, were further tested, as indicated in No. 18, by 
 raising the small end and allowing them to drop from 
 successive heights at 1, 2^ 3 and 4 feet. Under this test 
 a number of cracks developed, but in no case did the re- 
 inforcement fail. 
 
 Although it might appear from these results that posts 
 as here described have hardly enough strength to recom- 
 mend them for general use, it should be remembered that 
 ini many cases fence posts are not subjected to impact. 
 
378 CEMENTS AND CONCRETES 
 
 and it may prove more economical to replace from time 
 to time those which fail in this way than to use wooden 
 postS; which, being subject to decay, must all be replaced 
 sooner or later. 
 
 -A. 
 
 OS /O /S 20 2S <30 <5S -^S so 
 
 Diagram showing the effect of clay on cement mortars. 
 NO. 19. 
 
 Retempering. — Table III. illustrates the effect of re- 
 tempering Portland cement mortar. The mortars used 
 consisted of Portland cement and crushed quartzite be- 
 tween 1 and 2 millimeters in size, mixed in different pro- 
 
HOW TO USE THEM 
 
 379 
 
 portions. In each case, after the initial or final set had 
 taken place, sufficient water was added in retempering to 
 
 TABLE III. — Effect of Retempering on Cement Mortars. 
 
 Tensile Strength, in Pounds Per 
 Square Inch. 
 
 Treatment of Mortar. 
 
 
 1 Part 
 
 IPart 
 
 IPart 
 
 
 Neat 
 
 Cement, 
 
 Cement, 
 
 Cement, 
 
 
 Cement. 
 
 1 Part 
 
 2 Parts 
 
 3 Parts 
 
 
 a 
 
 odnu. fj 
 
 Sand, c 
 
 Qetnrl rf 
 
 i^cinu. 
 
 
 
 651 
 
 624 
 
 527 
 
 417 
 
 Mortar made up into briquettes . 
 immediately after mixing 
 
 
 650 
 673 
 634 
 
 701 
 624 
 581 
 
 493 
 529 
 480 
 
 385 
 421 
 403 
 
 
 
 679 
 
 610 
 
 492 
 
 409 
 
 Average 
 
 657 
 
 628 
 
 504 
 
 407 
 
 
 
 671 
 
 692 
 
 589 
 
 326 
 
 Mortar allowed to take initial 
 
 
 593 
 
 670 
 
 554 
 
 349 
 
 set, then broken up and made ^ 
 
 
 644 
 
 654 
 
 559 
 
 330 
 
 into briquettes 
 
 
 633 
 
 676 
 
 534 
 
 358 
 
 
 
 724 
 
 700 
 
 532 
 
 267 
 
 Average 
 
 653 
 
 678 
 
 554 
 
 326 
 
 
 
 455 
 
 527 
 
 492 
 
 364 
 
 Mortar allowed to take final 
 
 
 522 
 
 569 
 
 491 
 
 380 
 
 set, then broken up and 
 
 
 525 
 
 587 
 
 497 
 
 361 
 
 made into briquettes 
 
 
 558 
 
 566 
 
 486 
 
 315 
 
 
 
 642 
 
 568 
 
 531 
 
 345 
 
 Average 
 
 540 
 
 563 
 
 499 
 
 353 
 
 a Initial set, 1 hour 42 minutes; final set, 7 hours 15 minutes. 
 h Initial set, 1 hour 30 minutes* final set, 7 hours 15 minutes, 
 c Initial set, 2 hours; final set, 7 hours, 
 d Initial set, 2 hours 20 minutes; final set, 7 hours. 
 
 restore normal consistency. The briquettes were tested 
 at the age of four months. 
 
380 CEMENTS AND CONCRETES 
 
 Some Practical Notes. — Spencer B. Newbury, who is 
 an authority on the subject, says *^that the making of 
 good cement concrete is a comparatively simple matter, 
 and yet, like most simple operations in engineering, there 
 is a right way and a wrong way of doing it. Probably 
 nine-tenths of the concrete work done falls far short of 
 the strength it might develop, owing to the incorrect pro- 
 portions, use of too much water, and imperfect mixing. 
 All authorities are agreed upon the importance of thor- 
 ough mixing and the use of the minimum quantity of 
 water in all classes of concrete work. The matter of cor- 
 rect proportions of cement, sand, broken stones, etc., is 
 one which requires some thought and calculation, and by 
 proportioning these ingredients correctly an immense 
 saving in cost and increase in strength can easily be se- 
 cured. 
 
 The chief object in compounding concrete is to pro- 
 duce a compact mass, as free as possible from pores or 
 open spaces; in short, to imitate solid rock as closely as 
 possible. Cement is the essence of rock'' in portable 
 form, and. by its judicious use granular or fragmentary 
 materials may be bound together into solid blocks of any 
 desired size and shape, which in strength and wearing 
 qualities are at lea'st equal to the best stone that comes 
 from the quarries. Cement is, how^ever, very costly in 
 comparison with the other ingredients of concrete, and 
 must not be used wastefully. A little cement, judi- 
 ciously used, is better than a large quantity thj'own in 
 recklessly, as a little study of the principles involved 
 will plainly show. 
 
 To produce a compact mass from fragmentary ma- 
 terials, the voids must be filled. Imagine a box holding 1 
 cubic foot. If this were filled with spheres of uniform 
 
HOW TO USE THEM 
 
 381 
 
 size, the voids or open spaces would be one-third the total 
 volume, or 33 1-3 per cent., with spheres of various sizes, 
 as, for example, from large marble down to fine shot, the 
 voids would be much less, and it would theoretically be 
 possible, by the use of spheres of graded sizes, from the 
 largest down to dust of infinite fineness, to fill the box 
 completely, so that there would be no voids whatever. In 
 practice it is well known that the use of materials of 
 varying fineness gives the best concrete, since the voids 
 are much less than in materials composed of pieces of 
 uniform size. Hence the common practice of making 
 concrete with cement, sand, and broken stone, instead of 
 with cement and sand, or cement and stone only. The 
 sand fills the voids, and if the proportions are correct, a 
 practically solid mass results. As an example of this, 
 the writer found the briquettes of cement with three 
 parts of sand and four parts gravel showed higher ten- 
 sile strength at 28 days than those made with three parts 
 sand only. 
 
 The following table gives the relative weights of a 
 given volume of different materials, and also the per- 
 centage of voids, as determined by the writer. The ma- 
 terials were shaken down in a liter measure by giving 
 one hundred taps on the table, and weighed. In the case 
 of the broken stone a larger measure was used. The 
 voids were calculated from the specific gravity. 
 
 Comparison of the three different grades of Sandusky 
 Bay sand shows how greatly the percentage of voids 
 varies with the proportion of fine and coarse grains pres- 
 ent. The first is the natural sand, not screened, as 
 pumped up by the sand sucker from the bottom of the 
 bay, and contains a large amount of fine gravel. The 
 second is the same, passed through a 20-mesh screen to 
 
382 CEMENTS AND CONCRETES 
 
 remove the coarse particles. It will be seen that this 
 operation increases the proportion of voids from 32 to 
 38 per cent. The third is the same sand passing a 20- 
 mesh and retained on a 30-mesh screen, thus brought to 
 the fineness of the '^standard sand" used in cement test- 
 ing. This shows 40.7 per cent, of voids, owing to the uni- 
 form size of the grains. The same relation is seen in the 
 
 WEIGHT OF UNIT MEASURE AND PERCENTAGE OF VOIDS IN 
 VARIOUS MATERIALS. 
 
 Per Cent 
 of 
 Voids. 
 
 Portland cement 
 
 Louisville cement 
 
 Sandusky Bay sand, not screened 
 
 Sandusky Bay sand, through 20-mesh 
 
 screen 
 
 Sandusky Bay sand, 20-30 mesh (standard 
 
 sand) 
 
 Gravel, to % inch 
 
 Gravel, to inch 
 
 Marblehead broken stone (chiefly about 
 
 egg size) 
 
 82.3 
 
 38.5 
 
 40.7 
 42.4 
 35.9 
 
 47.0 
 
 two grades of gravel given in the table, that containing 
 finer grains showing much the lower percentage of voids. 
 These figures illustrate the imprudence of screening 
 any of the materials used in making concrete. The pres- 
 ence of clay in sand is, however, objectionable, not be- 
 cause of its fine state of subdivision, but because the 
 clay coats the sand particles and prevents the adhesion 
 of the cement. Such sand might be improved by wash- 
 ing^ but probably not by screening. It has been found 
 
HOW TO USE THEM 
 
 383 
 
 that cement which has been ground to dust with an equal 
 amount of sand goes much further when used for con- 
 crete than the same quantity of cement when used in 
 the ordinary way. This is doubtless owing to the fact 
 that the sand dust aids in filling the voids. It is also 
 well known that slaked lime, when added to cement mor- 
 tar, greatly increases the strength of mixtures poor in 
 cement. 
 
 From the figures given in the above table the compo- 
 sition of a theoretically perfect concrete may readily be 
 calculated. The existence of voids in the cement may be 
 disregarded, since in the process of hardening the cement 
 sends out crystals in all directions, completely encrusting 
 the sand particles and practically filling all the voids 
 which the cement itself contains. Examination of a 
 well-hardened briquette of cement with 3 parts sand, 
 after breaking, with the aid of a lens, will show this 
 clearly 
 
 Suppose, for example, we wish to make the best pos- 
 sible concrete from Portland cement with the sand and 
 gravel given in the above table. We should, of course, 
 choose the unscreened sand and gravel as containing 
 the least proportion of voids. One hundred measures of 
 gravel would require 35.9 measures of sand. As the 
 sand contains 32.3 per cent, of voids, we require 32.3 
 per cent, of 35.9, or 11.6 measures of cement. The pro- 
 portions would, therefore, be : Cement, 11 ; sand, 3, and 
 gravel, 9. It is customary, however, to increase the pro- 
 portion of mortar (cement and sand) by about 15 or 20 
 per cent., in order that the coarser materials may be 
 completely coated with the finer mixture. Making this 
 addition, we find the concrete proportions to be : Cement, 
 1 ; sand, 2.8 ; gravel, 7. Allowance must also be made in 
 
384 CEMENTS AND CONCRETES 
 
 practice for imperfect mixing;, since the materials can 
 never be distributed in a perfectly uniform manner. 
 Practically, with these materials, a concrete of cement 
 1, sand 2%, and gravel 6, would probably give the best 
 result, and little or no improvement would result from 
 increasing the proportion of cement. 
 
 A similar calculation shows that the correct propor- 
 tions for a concrete made of the sand and broken stone 
 given in the table would be 1 to 3 to 6 1^. Increasing 
 the amount of cement and sand by 20 per cent.^ w^e have 
 1 to 3 to 51/^. Probably 1 to 2i/2 to 5 would be found to 
 give the best results in practice. The determination of 
 the voids in the sand, gravel and broken stone used is 
 of the greatest value in adjusting the proportions of 
 concrete. 
 
 The simplest method of determining this in the case of 
 gravel and broken stone is to have a metal box made of 
 1 cubic foot capacity ; this is filled with the material to 
 be tested, well shaken down and struck off level. The 
 box and contents are then weighed. Water is now 
 poiured in until it rises even with the surface, and the 
 total weight again taken. The difference in the weights 
 is the weight of the water filling the voids of the ma- 
 terial. Now 1 cubic foot of water weighs 64-4-10 lbs., 
 and from the weight of the water found the percentage 
 of voids can be simply calculated. For example, in one 
 experiment the box and broken stone weighed 88 lbs. 
 After filling the spaces in the stone with water the 
 weight was 1171/2 lbs., a difference of 29^/2 lbs. The 
 percentage of voids is, therefore, 29^/2x100 divided by 
 62.4 equals 47 per cent. 
 
 In the case of sand this method- will not answer, as it 
 ig-; difficult to completely fill the voids of the sand by 
 
HOW TO USE THEM 
 
 385 
 
 adding the water. The voids can, however, be readily 
 calculated from the weight of a cubic foot and the spe- 
 cific gravity. The specific gravity of quartz sand is 
 about 2.65. A cubic foot of sand, free from voids, would 
 therefore weigh 2.65x62.4 equaling 165.4 lbs. The 
 weight of a cubic foot of sand, well shaken down, was, 
 however, found to be only 112 lbs., a difference of 53.4 
 lbs. The proportion of voids was, therefore, 53.4x100 
 divided by 165.4 equals 32.3 per cent. . The percentage 
 in voids in clean natural sand does not vary greatly, and 
 may be taken as 33 to 35 per cent, for coarse and 35 to 
 38 per cent, for fine sand. 
 
 We have already seen that with the materials above 
 described, concrete composed of 
 
 Cement 1, sand 2^/^, gravel 6, or 
 
 Cement 1, sand 2%, broken stone 5 
 by measure, will be practically compact and non-porous, 
 and that there is no object in increasing the proportion of 
 cement. Such concrete, if made from Portland cement, 
 will, however, be rather expensive, requiring about one 
 barrel of cement (equals 3^/2 cubic feet) for every cubic 
 yard. This is unnecessarily good for ordinary work, and 
 will only be required for foundations of engines and 
 other heavy machinery, in which the best possible result 
 must be secured regardless of cost. In cheaper concretes 
 the relative proportions of sand and broken stone should 
 be the same, as determined by the voids in the coarser 
 materials, while the proportion of cement may be varied 
 according to the required conditions of quality and cost. 
 Most excellent concrete may be made by using : 
 
 Portland cement 1, sand 7, stone or gravel 14. 
 
 Here are specimens of these two concretes, taken from 
 trial blocks laid Oct. 1, 1894, to determine the best pro- 
 
386 CEMENTS AND CONCRETES 
 
 portion for the foundation of brick pavement. The 
 richer of the two, 1-5-10, is certainly good enough for 
 any purpose, even for engine foundations. A cubic yard 
 of such concrete requires about % barrel of cement ; the 
 total cost of the cement^ sand and stone is about two 
 dollars per cubic yard. This is no more expensive than 
 concrete made from Louisville cement with 2 of sand 
 and 4 of broken stone, and is immensely superior to the 
 latter in strength. 
 
 The following table shows the results obtained in 
 Germany by R. Dykerhoff in determining the crushing 
 strength of various concretes. The blocks used were 
 inches square, and were tested after one day in air and 
 27 days in water. 
 
 Proportions by Measure. 
 
 Strength under Compressionc 
 Pounds per Square Inch. 
 
 Portland 
 Cement. 
 
 Sand. 
 
 Gravel. 
 
 1 
 
 2 
 
 
 2125 
 
 1 
 
 2 
 
 3 
 
 2747 
 
 1 
 
 2 
 
 5 
 
 2887 
 
 1 
 
 
 5 
 
 978 
 
 1 
 
 8 
 
 
 1383 
 
 1 
 
 3 
 
 5 
 
 1632 
 
 1 
 
 3 
 
 6X 
 
 1515 
 
 1 
 
 4 
 
 
 1053 
 
 1 
 
 4 
 
 5 
 
 1273 
 
 1 
 
 4 
 
 sX 
 
 1204 
 
 These figures prove the statement already made, that 
 mixtures of cement and sand are strengthened, rather 
 than weakened, by the addition of a suitable quantity 
 of gravel. It will be noticed that the mixture — cement 1, 
 
HOW TO USE THEM 
 
 387 
 
 sand 2, gravel 5 — is actually stronger than cement 1, 
 sand 2, without gravel. The same is shown in the mix- 
 tures 1 to 3 and 1 to 4. 
 
 In estimating the amount of material required to pro- 
 duce a given volume of concrete, it may be stated that 
 when very strongly rammed into place the volume of 
 concrete obtained frcm correct proportions of the ma- 
 terials will be about 10 per cent, more the volume 1 cubic 
 foot cement, 2^^ cubic feet sand, and 5 cubic feet stone, 
 and will therefore yield about 5"^^ cubic feet concrete. 
 
 Another Concrete Stairway and Steps. — A good stair- 
 case is one of the essential features in a building. The 
 safety and convenience of persons using a staircase are 
 not only affected by the due proportions and arrange- 
 ments of the steps, but by the strength and fire-resisting 
 properties of the materials employed, and the manner of 
 construction. The w^ells are in many cases too small, 
 out of proportion to the structure, which necessitates 
 dangerous winders, tiring high risers, narrow treads, or 
 insufficient headway. Some architects w^hen designing a 
 staircase pay little attention to the practicability of con- 
 struction. What may seem easy in theory or on paper 
 is often found impracticable or unnecessarily difficult 
 when reduced to actual practice. The errors of omission 
 and commission are left for the workmen to contend 
 with and overcome as best they may at the employer's 
 expense. Happily such cases are few, the majority of 
 architects supplying figured drawings, which are not 
 only a help and guide to the workmen, but also ensure 
 a practical staircase in due proportion and without un- 
 necessary expense. Staircases should be spacious, light, 
 and easy of ascent. It is generally admitted that a 12 
 inch tread and a 6 inch rise is the most convenient, and 
 
388 CEMENTS AND CONCRETES 
 
 that no tread should be less than 8 inches or more than 
 16 inches, and no rise less than 4^/2 inches and more than 
 7 inches. According to Blondel, the rise should be re- 
 duced y2 inch for every inch added to the tread, or the 
 tread reduced by 1 inch to every ^ inch added to the 
 riser, taking a 12 inch tread and a 6 inch rise as the 
 standard. Treads may be increased by means of a nos- 
 ing, which usually projects from 1 inch to II/2 inches. 
 Nosing not only gives more available space for the tread, 
 but also affords some advantage to persons going down 
 stairs, as the heel cannot strike against the rising. In 
 setting out a flight of stairs, the tread of the steps are 
 measured from riser to riser. Where practicable, the 
 number of steps from landing to landing should be odd, 
 because Avhen a person begins to ascend with the right 
 foot first (as most people do) he should end with the 
 same foot. Eectangular steps are called fliers. Wind- 
 ers, being narrowed at one end, are always more in- 
 convenient and dangerous than straight steps, and 
 should not be used for public buildings or other places 
 where there is a crowded traffic. Winders are also 
 more expensive to construct. They are, however, un- 
 avoidable in circular staircases, also in some instances 
 in angles, where a quarter or half space landing would 
 not give the desired rise. Winders should be so made 
 that the tread 6 inches from the end of the narrow 
 point should be wide enough to step upon without dan- 
 ger of slipping. No stairs should be less than three 
 feet from the wall to the hand-rail. A width of 3 feet 
 6 inches will allow two persons to walk arm in arm up or 
 down stairs. A width of 4 feet 6 inches is generally used; 
 this gives plenty of space for two persons to pass each 
 other. No hard and fast rules can be laid down for the 
 
HOW TO USE THEM 
 
 389 
 
 size of treads and risers, as they are regulated more 
 or less by the size of the well and the height from floor 
 to floor. Too few steps in a flight are as bad as too 
 many. There should not be less than three. Long 
 straight flights of steps are tiring and dangerous. The 
 straight line of length should be broken by landings, 
 so that there may not be more than eleven continuous 
 steps. Landings give ease in ascending and safety 
 when descending. No landing should be less in length 
 than the width of the staircase. The staircases in the 
 pre-Elizabethan style were usually plain, dark and in 
 long narrow flights ; but with the Elizabethan archi- 
 tecture came in a more commodious, light and decora- 
 tive style. Wood stairs are often enriched with plaster 
 work, the soffits being panelled with plaster, and the 
 strings adorned with composition or plaster enrich- 
 ments. Stone stairs are also frequently enriched with 
 plaster mouldings in the angles of the soffits and walls.. 
 External steps and landings are usually made with a 
 fall of ^4 inch to the foot to allow rain to fall off. 
 
 Cast Concrete Stairs. — Concrete is now fast super- 
 seding stone, wood and iron for staircase construction, 
 where strength, durability and economy and fire-resist- 
 ing properties are required. Cast concrete stairs were 
 first introduced nearly sixty years ago. The stairs 
 Avere cast in single steps, or in treads or risers, and 
 fixed in the same way as natural stone. Square and 
 spandrel steps, risers and treads are cast in wood 
 moulds; circular steps and curtails in plaster moulds. 
 Spandrel steps should have the wall or ^^taiP' end 
 formed square, and about 4^/2 inches deep, to give a 
 better bed and bond in the wall. A good mixture is 3 
 parts of granite or slag chippings and 1 of Portland 
 
390 CEMENTS AND CONCRETES 
 
 cement, ganged stiff, and well rammed into the monlds. 
 When set they are removed from the monlds, air dried, 
 and placed in water or a silicate bath, and treaded in 
 a similar way to that described for slabs. For long 
 steps pieces of T iron^ or iron pipes, are sometimes in- 
 serted in the centre of the concrete while being cast. 
 The iron is not actually required to strengthen con- 
 crete properly made, but is used to give a temporary 
 strength to the cast while it is green, so as to allow 
 more freedom and security in handling the cast when 
 it is being taken from the mould and moved about till 
 permanently fixed. Landings are cast in a similar way, 
 but unless very small, they are best done in situ. I 
 have made landings up to 40 feet superficial, but owing 
 to the cost of transit, hoisting and fixing they were 
 not profitable. 
 
 Tests of Steps —The following examples show the 
 strength of concrete steps : In Germany, when con- 
 structing a concrete stair, with square steps 3 feet 4 
 inches long, and 6-inch tread, and 6i/2-inch rise, and 
 one end set 8 inches into the walls, four steps were sub- 
 mitted for trial, and 5,940 lbs. weight of iron were 
 gradually piled on them. The steps showed no signs 
 of fracture, but no more weight could be put on be- 
 cause the masonry began to yield. The load was left 
 on three days, and the steps remained unaffected. Al- 
 though numerous tests have been made of concrete 
 floors and blocks, few have been made for concrete 
 steps. The following may be given as a reliable one: 
 The steps were about 6 feet long, 11-inch tread and 
 6-inch rise. Every step was tested in the presence of 
 the foreman concreter and author. The steps were 
 supported at both ends, and weighed with a distribu- 
 
HOW TO USE THEM 
 
 391 
 
 tive load. The majority, which were matured by age, 
 passed the specification standard. 
 
 Concrete Stairs Formed 'Hn Situ,^^ — Concrete stairs 
 are an outcome of stairs built with cast concrete steps. 
 Stairs formed in situ were introduced in 1867. The 
 idea was suggested by the use of reverse moulds for 
 fibrous plaster work, and in the formation of concrete 
 dormer windows made in situ on some mansions. The 
 step landings and the wall bond, being a monolith 
 structure, were to a certain degree self-supporting. 
 They tend to strengthen instead of to weaken the 
 walls. Architects generally supply drawings of the 
 intended staircase, but as there is often a differ- 
 ence in the size of the details of the actual work and 
 the drawings^ it is necessary that the workman should 
 have a practical knowledge of setting out the height'' 
 and ^^go" for the pitch board, to suit the landings and 
 the well of the staircase, and ensure the necessary head- 
 room. 
 
 Setting Out Stairs —A correct method of setting out 
 the framing for concrete stairs is of primary import- 
 ance. The height of a stair is the length of a per- 
 pendicular line drawn from the upper of a floor to 
 that of the one immediately above it. The ^^go" is 
 the length of a horizontal line drawn along the centre 
 line of the flight of steps or stair space. The exact 
 height and widths should be taken on a rod, which 
 should afterwards be used for setting out the work. 
 Never work without this rod, as it is quicker and more 
 accurate than measuring with a 2-foot rule. There are 
 various ways of getting the dimensions of treads and 
 rises. The following is a simple one and answers for most 
 purposes. The height and go are taken and suitably 
 
392 CEMENTS AND CONCRETES 
 
 divided. For example, if the height from floor line to 
 floor line is 9 feet 3 inches, and it is proposed to 
 make each rise 6 inches high, reduce the weight to 
 inches, which would be 111 ; divide by the proposed 
 height of each step — 6 inches — the quotient will be 18, 
 giving the same quotient 6 and 3-18. If there are 
 intermediate landings, or half spaces, their dimensions 
 must be allowed for. The size of the tread is obtained 
 by dividing the ^^go" by the number of steps. The 
 quotient will be the width of the tread. Great care 
 should be taken in setting out the rods and pitch 
 boards. It is better to measure thrice than to cut twice. 
 When the string line is marked on the wall, a chase 
 about inches deep is cut into the wall. It is not 
 necessary to cut the chase straight at the soffit line, as 
 it is apt to cut into a half, or rather a whole brick, 
 and leave the ends loose. The irregular line of chase 
 below the soffit line can be made solid during the pro- 
 cess of filling in the steps. The chase should be cut 
 as the work proceeds. Not more than one flight at a 
 time should be cut, to avoid weakening the wall. In 
 some instances a brick course in sand is left by the 
 bricklayers. The bricks are then taken out as the 
 work proceeds. 
 
 Nosings and Risers, — ^Nosing mouldings should be 
 strong and bold. A simple but well-defined moulding 
 not only gives greater strength, but is more in keep- 
 ing with its purpose than one with numerous or small 
 members. Nosing and riser moulds are best formed 
 in two parts, the nosing moulds being one part and the 
 riser board the other. To cut them out of the solid 
 would not only be expensive, but also cumbrous to fix. 
 They can be run ^t most saw and moulding mills, 
 
HOW TO USE THEM 393 
 
 They should be run in lengths and then cut and mitred 
 on the job. Illustration No. 20 shows various forms 
 of nosing. Fig. 1 is a simple nosing for common work. 
 Fig. 2 may be used for school stairs^ etc. Figs. 3 and 
 4 are well adapted for a good class of work. It will be 
 seen that the lower edges of the riser boards are 
 splayed. This is to admit the shoe of the running 
 mould; also a trowel to Avork close up to face of the 
 
 Fig. 1. Fig. Fig. 3. F^g. 4. 
 
 1^ 
 
 Sections ob Nosing 
 "iviqulds with klser" boards. 
 
 NO. 20. 
 
 concrete riser when running and trowelling off the 
 treads. The dotted lines indicate the line of tread. 
 Nosing moulds are cut in the centre of the section, and 
 afterwards the two parts are held in position with 
 screws while the steps are being filled in. This allows 
 the upper part to be unscrewed and taken off when the 
 stuff is nearly set, thus allowing more freedom to 
 trowel the surface of the tread; also to make a better 
 joint while the stuff is green, and at the part that is 
 cast and the part to be trowelled. The joint in the 
 nosing mould leaves a thin seam which is easily cleaned 
 off, w^hereas the joint of the tread and nosing is not 
 only seen more, but is also more difficult to make good. 
 
394 CEMENTS AND CONCEETES 
 
 Illustration No. 21 shows the mould and joint and 
 screws for fixing same. 
 
 Framing Staircases. — The wood framing for con- 
 crete stairs differs from and is partly the reverse to 
 that used for wood stairs. The nosings are formed the 
 reverse of the moulding, and the whole framing is so 
 constructed that it forms a mould to cast all the steps 
 and landings, from floor, in monolithic form, or one 
 piece. When the positions of half spaces or other 
 
 Jointed Nosing Mould 
 WIQTH KisER Board. 
 NO. 21. 
 
 landings are set out on the walls, strong planks are 
 fixed on edges so as to give fixing joints for the car- 
 riage and outer strings. The strings are then fixed 
 to act as guides for fixing the centring, risers and nos- 
 ing moulds. Where practicable, the outer string shoidd 
 be so arranged in the fixing that it can be taken off 
 after the concrete is firm without disturbing the cen- 
 tring. This allows the returned ends of the steps to 
 be cleared off while the work is green. The carriage 
 boards are fixed from landing to landing. Illustra- 
 tion No. 22 shows the forms and positions of the vari- 
 
396 CEMENTS AND CONCRETES 
 
 ous parts, with their names. BuUnoses or curtails and 
 circular parts of nosings are formed in plaster moulds, 
 which are run with several reverse running moulds. 
 
 Staircases between walls are more simple than open 
 staircases; therefore they are more eas}^ to frame up. 
 The string boards are cut to the reverse of that used 
 for wood stairs. A string is cut for each wall. The 
 riser boards are then fixed to the wall strings. The 
 centring for the soffits is fixed independently, the 
 boards being laid on fillets which are nailed on each 
 wall. For short flights of steps or common stairs, such 
 as for cellars, etc., string boards may be dispensed with. 
 The positions and sizes of the risers, treads, soffits and 
 landings are first set out and marked on the walls. 
 Riser fillets are then nailed on the walls, taking care 
 to keep each fillet in a line with the riser mark, and 
 to allow for the thickness of the riser boards which 
 are subsequently nailed on the inner sides of the fillets. 
 Riser boards for winders are generally hung on long 
 fillets and then nailed on the walls. Long fillets ex- 
 tending upwards enable the work to be easier and more 
 strongly fixed, as they cover more brick joints than if 
 cut to the exact height of the riser. 
 
 Centring for Landings and Soffits, — Centring for 
 landings and the soffits of stairs should be made strong 
 and true. The timber should be well seasoned, to pre- 
 vent warping or shrinkage. The outer angles of land- 
 ings should be supported by strong wood props, not 
 only to carry another prop for the landing above. AH 
 centrings should be made perfectly rigid, to stand the 
 weight of the concrete and the ramming. Great care 
 should be taken that the timber framing is securely 
 supported, as any deflection will not only throw the 
 
HOW TO USE THEM 
 
 397 
 
 work out of level, but will also tend to crack the con- 
 crete. The principal props should be cut about I/2 
 inch shorter than the exact height. They are placed 
 on a solid bed. the %-inch space at top being made 
 up with two wedges, the thin ends being inserted in 
 opposite directions and gently driven home from each 
 side until the exact height is obtained. If it is dif- 
 ficult to get the top of the prop, the wedges can be 
 inserted at the bottom. The use of the wedges will 
 be seen when the centring is struck. If there are 
 winders in the stairs, the centring for the soffit will be 
 more or less circle on circle. This form of centring 
 is done by lathing, with 1-inch boards, cut to a taper, 
 the surface being made fair with a gauged lime and 
 hair. Rough 1%-inch boards are used for the centring. 
 This should be close-jointed. Open joints or sappy 
 timber act as a sieve, and allow liquid cement to drip 
 through, thus robbing the concrete of its strength. 
 
 Waterproof Centring.ii — The following is a method 
 that has been used with marked success for the sof- 
 fits of stairs, landings and the ceilings of floors. The 
 initial cost of preparing is small, and is repaid with 
 interest by the decreased cost ,of setting and the in- 
 creased strength and solidity. For ordinary work, 
 such as w^arehouses, etc., it is very suitable, as a fin- 
 ished surface is formed, and no setting required. It 
 seems strange that, when casting concrete work out of 
 a wood or a plaster mould, the mould is seasoned, and 
 every precaution taken, not only to stop suction, but 
 also to prevent the escape of liquid cement; but when 
 casting a large surface in situ (where every precau- 
 tion should be taken to obtain the maximum of 
 strength), any kind of centring (which is a mould) 
 
398 
 
 CEMENTS AND CONCRETES 
 
 is thought good enough, if only sufficiently strong to 
 carry the concrete till set. I am aware that many 
 workers in concrete think that an open or porous 
 centring is a benefit instead of a defect, simply be- 
 cause it affords an escape for excess of water. But 
 why have excess of water at all? There is no gain 
 in time or strength, but a direct loss in both points. 
 The excess water descends through the concrete by 
 force of direct gravitation, and always carries a cer- 
 tain amount of liquid cement with it to the centring, 
 leaving the aggregate more or less bare, and the body 
 of the concrete weak. A part of the liquid cement 
 also oozes through the joints and crevices, which leaves 
 the skin of the concrete bare and broken. There is 
 no reason or excuse for excess water, and it is simply 
 the result of ignorant or careless gauging, which is not 
 only a waste of time, water and cement, but a loss in 
 the ultimate strength, and the cause of cracks. Porous 
 centring is also a dirty process. The overhead drip, 
 drip, is neither good for the workmen nor the material 
 underneath. 
 
 The process of forming the rough centring boards 
 watertight is simple and expeditious, being done by 
 laying the rough board surface with a thin coat of 
 gauged plaster ; and when the centring has been struck 
 the plaster will come with the boards, leaving the con- 
 crete with a fair face. The ramming forces a certain 
 amount of water to the lower surface or centring, and 
 this is so close and fine that it takes an exact impress 
 of it ; consequently the truer and smoother the centring 
 the truer and smoother the concrete surface. The film 
 of water indurates the skin of the concrete and prevents 
 surface or water cracks. It will be noticed when filling 
 
HOW TO USE THEM 
 
 399 
 
 in dry or porous plaster moulds that the concrete cast 
 produced has a surface either friable when newly cast, 
 or when dry the surface is full of small water lines, 
 like a map, or a broken spider's web. This is owing 
 to the suction caused by the porous nature of the mould 
 and the water escaping through the weak or open parts 
 leaving corresponding lines on the concrete surface. 
 These defects are obviated by using waterproof cen- 
 tring. 
 
 Where fineness of finish is not required, such as ware- 
 house floors, the surface can be made sufficiently fair 
 and smooth when fiJling in the concrete without sub- 
 sequent setting. The plaster is laid on the centring, 
 and made fair and smooth, and then the surface is 
 saturated with water to correct the suction; or the 
 surface, if dry, may be brushed over with a thin soap 
 solution to j)i"event adhesion. On this surface a coat 
 of neat cement about % inch is laid, and on this the 
 concrete is placed. The two unite in one body, and 
 when set, and the centring struck, the plaster sheet 
 comes with the boards, leaving a smooth surface. This 
 surface can be made in color by lime washing, which 
 will also give more light, or a finished white surface 
 can be obtained by substituting parian or other white 
 cement for the neat Portland cement. The concrete 
 must not be laid until the white cement is firm, not set, 
 otherwise the concrete will force its way in thin or 
 soft parts and disfigure the surface. I have success- 
 fully used this method for obtaining a finished sur- 
 face when encasing iron girders with concrete for fire- 
 proof purposes. 
 
 Staircase Materials. — With regard to the materials 
 for a concrete staircase^ no one who intends to con- 
 
400 CEMENTS AND CONCRETES 
 
 struct them substantially, fireproof and economically, 
 can afford to use common substances, when by judi- 
 cious selection and for a trifling additional first cost a 
 combination of materials can be obtained, which, if 
 not (strictly speaking) fireproof, is at least the most 
 incombustible constructive compound known. This is 
 a quality of the most vital importance in modern house 
 construction. Portland cement and slag cement are 
 the best known matrices. The finer Portland cement 
 is ground, the greater its heat-resisting powers. Slag 
 cement is lighter than Portland cement, and its fire- 
 resisting properties exceed those of both gypsum and 
 Portland cement. But as its manufacture is as yet 
 somewhat limited, and its strength not uniform, ex- 
 ceptional care must be exercised in testing its general 
 qualities before using it for staircases. Broken slag, 
 firebricks, clinkers and pottery ware are the best ag- 
 gregates, being practically fireproof. All should be 
 clean, and in various graduating sizes, from that of a 
 pin's head to that of a walnut, for roughing out with. 
 The topping should be the same as that described for 
 Eureka paving. 
 
 Filling in Stairs, — Before gauging the materials, 
 sweep out all dust in the interior of the framing and 
 the wall chase and then wet the latter, and oil the 
 woodwork. If the wood of the nosing moulds and 
 risers is sappy or open grained, the long lengths, be- 
 fore being cut and fixed, should be made smooth and 
 indurated by coating with a solution of hot paraffin 
 wax. The smoother and less absorbent the surface of 
 the wood, the more readily and cleaner will the mould 
 leave the cast work. Paraffin also renders the wood 
 damp-proof, thus preventing swelling or warping. For 
 
HOW TO USB THEM 
 
 401 
 
 ordinary purposes one or two coats of paraffin oil will 
 be found sufficient. This should be done two or three 
 hours before the steps are filled in^ so as to allow the 
 oil to partly dry in and stop the pores of the wood. 
 If the wood absorbs all the oil, and has a dry sur- 
 face, brush the surface again with paraffin, using a 
 semi-dry brush. This should be done as the work pro- 
 ceeds. If the surface is over wet, the oil mixes with 
 the cement, thus causing a more or less rough sur- 
 face. Soap solution may be safely used for rough 
 concrete, or where a rough surface is left to be sub- 
 sequently set. In the latter case the surface must be 
 well wetted with water and scrubbed before the final 
 coat is applied. Soap solution may also be used for 
 rough framing, such as soffit boards, but soap should 
 not be used for fine concrete or a finished surface, 
 as it leaves a film of grease which has a tendency to 
 prevent the cement adhering when clearing up or mak- 
 ing good the finished surface. As the work of filling 
 proceeds, the surface should be brushed over with a 
 slip, that iS;, neat cepaent, to fill up all angles, and 
 obtain a surface free from bulbs" and ragged ar- 
 rises. 
 
 The coarse concrete for roughing out the stairs is 
 composed of 1 part of Portland cement and 3 parts of 
 coarse fireproof aggregate. These material-s must be 
 gauged stiff and laid in small portions of about a pail- 
 ful at a time, taking care to thoroughly consolidate 
 by ramming and beating with a wooden mallet, using 
 a wooden punner or punch to get into the angles and 
 deep parts. When the first layer, which may be about 
 3 inches thick, is rammed, another layer is deposited 
 and rammed, and so on until the rough stuff is within 
 
402 
 
 CEMENTS AND CONCRETES 
 
 % inch of the line of tread. It must not be omitted to 
 brush the strings, treads and nosing moulds with slip 
 as the work proceeds. This is most effectually done 
 by the aid of a tool-brush. Care must be exercised 
 when ramming stairs with mallets or punches that the 
 mallet or other implement used is not too large or too 
 heavy, for it would most likely cause the framing to 
 bulge out, and the form of the work would be irre- 
 trievably spoilt. During the operation of ramming 
 some of the water and a part of the constituent of the 
 cement is forced upwards, and leaves a thin, smooth, 
 clayey film on the surface, which prevents the adhesion 
 of the next layer. For this reason the successive lay- 
 ers should be deposited before the previous one is set, 
 and the topping should be laid while the coarse con- 
 crete is yet green. Too much stress cannot be laid upon 
 the importance of topping the rough coat while it is 
 green. This is one of the secrets of success of solid 
 and strong work, so no more rough stuff should be laid 
 than can be topped before the rough is set. 
 
 The fine stuff for the topping is the same as for 
 Eureka paving, viz., 1 part of cement to 2 parts of fine 
 aggregate, gauged firm and plastic. The tread is made 
 level and fair by means of a running mould so formed 
 that it bears on the nosing moulds above and below the 
 tread. The mould has a metal plate or ''shoe" fixed 
 so as to run and form the tread. The shoe projects 
 so that it will work under the riser board close up to 
 the concrete riser. Illustration No. 23 shows a sec- 
 tion of steps with the mould in position; also a sec- 
 tion of the nosing mould and soffit boards and car- 
 riage. The end of the slipper next to the wall is cut 
 short to ^llow the mould to run close up to the walL A 
 
HOW TO USE THEM 
 
 403 
 
 section of a T iron is shown as sometimes used as an in- 
 ternal support. Iron is used for long steps, or where 
 stairs are intended for heavy traffic. Iron helps to sup- 
 
 — Sections of Framing of Soffit op Stair, Riser 
 And Noser Mould, with Concrete and Tread Run- 
 king Mould in Position. 
 
 NO. 28. 
 
 port the concrete until set; it is placed in alternate 
 steps, or in every third or fourth step, according to the 
 length of step. Ordinary sized steps require no iron, 
 
404 CEMENTS AND CONCEETES 
 
 unless as a support for the concrete while green, and 
 during the process of making. 
 
 Finishing Stairs. — When the treads are firm after 
 being run, the upper part of the nosing moulds are 
 removed, the surface and joists trowelled off. The ad- 
 vantages of having the nosing mould in two parts will 
 thus be seen, as it allows the joint at this most notice- 
 able part to be neatly cleaned off while the work is 
 green. The lower part of the mould will support the 
 concrete nosing during the finishing of the tread and 
 until the concrete is set. If the work is done with a 
 nosing mould in one piece, which necessitates its being 
 left on until the concrete is set, the joint has then to be 
 filed down and stopped, and however well done, has a 
 patchy appearance. When the treads are finished, and 
 the work set, but not dry, the riser and string boards 
 are taken off, the joints made good, and the returned 
 end of the steps cleaned off. If the stuff has been 
 properly gauged and rammed, there should be little 
 or no making good required, but it is important that 
 if necessary it should be done while the work is green. 
 A thin layer of neat cement will not adhere on a dense 
 and dry body of concrete. The only way to obtain 
 perfect cohesion is to cut the damaged surface out to 
 a depth of not less than ^4 inch, then thoroughly wet 
 it, brush the surface with liquid cement, and fill it in 
 with gauged cement. No traffic should be allowed on 
 the treads during the process of setting and harden- 
 ing. The work is further protected and hardened by 
 covering w^ith sacks kept wet for several days by fre- 
 quent watering. Where there are several flights of 
 stairs to construct, there should not be less than three 
 sets of strings and riser boards, which will enable the 
 
HOW TO USE THEM 405 
 
 carpenter to fix one set while the plasterers are filling 
 in and cleaning off the others. 
 
 Non-Slippery Steps. — Incessant traffic tends to make 
 the treads of steps more or less slippery. In order to 
 obviate this, the surface is indented with a concrete 
 roller, similar to that used for some kinds of paving. 
 Another way is to form three or four V-shaped grooves 
 from 1 inch to 2 inches apart on the treads while the 
 concrete is moist. Another way is to insert leaden 
 cubes about 1 inch square " from 2 to- 3 inches apart 
 in the surface of the treads. Well-seasoned, hard 
 wooden blocks, about the same size as the lead and 
 fixed in a similar way, keeping the end grain vertical, 
 are also used for this purpose. India rubber and cork 
 cubes may also be used. 
 
 Striking Centrings. — This should not be attempted 
 until all the other work, with the exception of finishing 
 the soffits, is done. It will be understood that the 
 framing can be arranged so that the string and riser 
 boards can be taken off without disturbing the soffit 
 centring, which is kept up as long as possible. The 
 time for striking centring greatly depends upon the 
 class of cement used, the manner of gauging and lay- 
 ing the concrete, and the temperature; but generally 
 speaking, centring should not be struck for at least 
 ten days. A stair between the walls can be struck 
 much sooner than one having only one bearing by which 
 its own weight is carried. I have seen a stair, with 
 steps projecting 3 feet 6 inches from the wall, cleared 
 of all supports in five days from the time of filling 
 in ; but this was with good cement, gauged 1 part to 2 
 of aggregate, and in warm weather, and the stair was 
 strengthened with T iron. 
 
406 CEMENTS AND CONCRETES 
 
 The centring and framing for a flight of stairs should, 
 where practicable, be independent of other stairs above 
 or below, so that they can be struck in due rotation. 
 The wedges of the main props should be gradually 
 withdrawn. This tends to avoid the sudden jar which 
 otherwise often happens when the centring is too sud- 
 denly struck. The sudden removal of centring and 
 the inflexible nature of concrete are the cause of body 
 cracks. The damage caused by the sudden jar may 
 not be seen at the time, but it will be eventually devel- 
 oped by the force of expansion, which always finds out 
 the weak spots. 
 
 Concrete and Iron. — Iron pipes, bars and T pieces 
 are sometimes used with concrete stairs where the steps 
 are long, or where landings have little support from 
 walls. They help to carry the dead weight until the 
 mass is thoroughly set, and also prevent sudden de- 
 flection if the centring is struck too soon. When iron 
 pipes are used for steps they should go right into the 
 wall chase. Iron T pieces are used for long landings. 
 Care must be taken that, if the iron is used, no part 
 should be left exposed. It must be embedded in the 
 concrete to protect it from oxidization and the effects 
 of fire. AVhen iron girders, etc., are partly exposed, 
 they should be painted. Iron bars or pipes are occa- 
 sionally used to strengthen the outer strings of spandrel 
 stairs. The iron is laid in the moist concrete 
 near and along the string, having the ends projecting 
 into the walls or landings. Angle irons are often used 
 for unsupported concrete angles. Iron pipes, bars or 
 joists are used as integral supports for landings and 
 floors having unsupported ends. 
 
 The tensile strength of bar iron is materially in- 
 
HOW TO USE THEM 
 
 407 
 
 creased by twisting. A bar % inch square with three 
 twists per foot will gain about 50 per cent, in tensile 
 strength when embedded in concrete, and give a corre- 
 sponding strength to the concrete. A combination of 
 iron and concrete is of special service where space is 
 limited. For instance, if a beam or landing requires 
 a certain thickness to carry a given weight, and it is 
 inconvenient or difficult to obtain that thickness, the 
 requisite degree of strength with a reduced thickness 
 may be obtained by the combination of both materials. 
 This gives the combined iron and concrete a useful ad- 
 vantage over stone. It is important to secure the full 
 strength of the iron, and that none be lost or neutral- 
 ized. In order to obtain the full strength the iron 
 should be judiciously placed. Thus, a piece of iron 
 surrounded by twenty times its sectional area of con- 
 crete would increase the weight-sustaining power of the 
 iron in the centre and would have its strength in- 
 creased about twice. If the same quantity of iron was 
 placed in several pieces, so as to throw as much tensile 
 strain on the iron as possible, the strength would be 
 increased nearly four times. In order that none of the 
 strength be lost or neutralized, the iron should be 
 placed near the lower surface ; if fixed higher, they are 
 nearer the axis of neutral stress, and are correspond- 
 ingly less effective. The use of iron in concrete is in= 
 valuable for many constructive purposes, but for gen- 
 eral work, unless as a temporary aid and in a few ex- 
 ceptional cases, it is unnecessary. For all other things 
 being equal, the huge board of reserve strength in good 
 concrete is alone sufficient to sustain as great if not 
 a greater weight than that sustained by natural stone. 
 No other artificial compound exceeds the strength of the 
 
408 CEMENTS AND CONCKETES 
 
 natural substance, as does artificial stone composed of 
 Portland cement concrete. 
 
 Setting Concrete Soffits. — The soffits of stairs and 
 landings, if neat cement has been used on a water- 
 proof centring, as already described, only require a lit- 
 tle stopping and coloring, but for- work done on rough 
 centring a setting coat has to be laid. This is usually 
 done with neat Portland cement, though it is frequently 
 gauged with lime putty to make it work more freely. 
 The surface should be well roughened and wetted, to 
 give a key and obtain perfect cohesion. It requires 
 great care and time to make a good and true surface 
 with Portland cement on a body of concrete, espe- 
 cially if the concrete is dry, which is generally the 
 case where there are several flights of steps in a stair- 
 case, and the setting of the soffits and landings are 
 left to the last part of the work. I have obtained 
 equally good results by using Parian or other white 
 cements for setting the soffits of staircases. When 
 using white cements for this purpose it is better to 
 brush the concrete surface with liquid cement before 
 laying the gauged cement. The laying trowel should 
 follow the brush, or at least before the liquid cement 
 dries in. This not only secures better cohesion, but 
 tends to prevent the setting coat peeling when trowel- 
 ling it off. Soffits are sometimes set with gauged put- 
 ty. This is like putting a beggar on horseback, and 
 the work is never satisfactory. 
 
 Fibrous Concrete. — As already mentioned, canvas 
 and other fibrous materials may be advantageously 
 used with Portland cement for several purposes. Can- 
 vas forms a good ground for a setting coat on concrete 
 surfaces. It gives a uniform and strong key, prevents 
 
HOW TO USE THEM 
 
 409 
 
 surface cracks, and the final coat from peeling. Coarse 
 canvas cut to convenient sizes is used. It is laid on 
 the centring, and held in position with tacks, or with 
 the same kind of cement as intended for the final coat. 
 The canvas is then brushed with liquid cement, and 
 then the concrete is laid while the canvas is moist, so 
 that the whole will form one compact body. When the 
 centring is struck, the fibrous concrete surface is rough- 
 ened with a sharp and fine drag, so as to raise the 
 fibre of the canvas, thus giving a fine, regular and 
 strong key. This surface requires less material for the 
 final coat than the ordinary concrete surface. If tacks 
 are used they must be extracted before the final coat is 
 laid, to avoid discoloration. The rough concrete and 
 the white surface coat may also be done in one opera- 
 tion. The centring is made fair and smooth, and then 
 oiled with chalk oil. The white cement is gauged stiff 
 and laid on the centring. Coarse canvas is then laid 
 on and well brushed with liquid cement. When this 
 is firm (but not set) the surface is again brushed, 
 and then the concrete is laid. The concrete is deposited 
 in two or more layers. The first must not be too thick, 
 taking care that it is well rammed or pressed on the 
 moist canvas surface without disturbing the white ce- 
 ment. .After the centring is struck any defects on 
 the surface are made good. The surface may be then 
 left white, or painted, or polished as required. 
 
 Polished Soffits, — Soffits, landings and strings of con- 
 crete stairs that are finished in white cement may be 
 polished. The material may be tinted, or left in its 
 natural white or creamy color. Polished cement work 
 is always bright, and has a lustre like marble. Be- 
 ing durable and easily cleaned^ it is more sanitary and 
 
410 CEMENTS AND CONCRETES 
 
 cheaper than paint. The polishing is done the same 
 way as described for white work." 
 
 Concrete Staircases and Fibrous Plaster, — Fibrous 
 plaster is well adapted for concrete surfaces when an 
 enriched finish is desirable. I have introduced this 
 material for decorating the soffits of steps and land- 
 ings ; also the strings of concrete stairs. By this method 
 the soffits may also be enriched^ and strings can be 
 panelled; or enriched with medallions or foliage, as re- 
 quired. The soffits may also be enriched with modelled 
 work done in situ^ with some of the white cements, or 
 with plaster and tow. The strings may be decorated 
 with hand-wrought gesso. In order to obtain a fixing 
 or keying substance that will receive nails or screws 
 to sustain the fibrous plaster, a rough plan of the de- 
 sign, or rather the fixing points, is set out on the in- 
 side of the centring before the concrete is laid. On 
 these plans wood plugs, fillets or concrete fixing blocks 
 are laid, and held in position with nails, plaster or ce- 
 ment until the concrete is laid and set. Care must be 
 exercised when fixing the plugs or fillets that the 
 centring will leave freely without disturbing the plugs, 
 etc. 
 
 Dowel Holes. — Cutting dowel holes in concrete to 
 receive iron or wood balusters is a slow and tedious 
 process. The}^ are best formed by means of wooden 
 plugs, which are fixed before treads; the plugs are 
 driven into the rough concrete before it is set, leaving 
 them flush with the line of tread, so that when the 
 topping is laid they will not be in the way. Plugs 
 are best fixed by the aid of a wooden gauge. The 
 gauge is made the same thickness as the topping, the 
 length being equal to the distance between the nosing 
 
HOW TO USE THEM 
 
 411 
 
 mould and the riser boards and as wide as will admit 
 of plug holes and the plugs to be driven through. The 
 plugs are made a little larger than the baluster ends 
 to allow for the lead. The gauge is laid on the rough 
 concrete, using the returned nosing as a guide, and then 
 driving the plugs flush with the top of the gauge. 
 The gauge is then lifted up and laid on the next step, 
 and so on until the finish. This method is accurate 
 and saves measuring and marking the position of each 
 hole on every step. When balusters are fixed on the 
 ends of the steps, the plugs are fixed on the inside of 
 the outer string. The plugs are generally left in until 
 the balusters are ready for fixing. A ready method 
 for forming lewis" holes or other undercut sink- 
 ings in concrete is performed by casting wedge-shaped 
 blocks of plaster of the required form and size, and 
 then laying them in the desired positions while the 
 concrete is soft. When the concrete is set, the plaster 
 blocks can then be easily cut out, leaving the under- 
 cut sinking as desired. 
 
 Summary of Staircases Constnicted ^^in Situ.'^ — It 
 will be seen from the foregoing that the operations em- 
 ployed in the construction of concrete staircases formed 
 m situ are: (1) setting out the stairs and landing; (2) 
 fixing the wood framing; (3) gauging the materials and 
 filling in; (4) removing the framing; (5) cleaning up 
 the treads, risers and strings; (6) striking the soffit 
 centring and finishing the soffits; (7) protecting and 
 wetting the work until set and hard. 
 
 Cast Steps. — Staircases are also constructed with 
 steps cast separately, and then built in, in the same way 
 as stone. Illustration No. 24 shows various sections 
 of steps. Fig. 1 is a spandrel step, which may be used 
 
412 CEMENTS AND CONCRETES 
 
 for model dwellings, factories, etc. The tread is grooved 
 to afford a good footing and prevent dipping. The 
 dotted line indicates a square seating or tail-end of the 
 step, which is embedded in the wall. Fig. 2 is a square 
 \ step. Fig. 3 is a step with a moulded and returned 
 
 Fig. I. Fig. 2. Fig. 3. Fig, 4. 
 
 Sections or Steps. 
 
 NO. 24. 
 
 nosing. F'ig. 4 is a similar step, but having a moulded 
 soffit. For cast work these steps must have a square 
 seating or tail-end, as indicated by the dotted lines on 
 Fig. 1, so as to bond into the wall. 
 
 NO. 25 
 
 Treads and Risers, — Stairs between walls are some- 
 times formed with treads and risers. The treads and 
 risers are cast and built in as the construction of the 
 work proceeds. Sometimes they are let into chases and 
 pinned after the walls are built. Illustration No. 25 
 shows ei section of treads and risers. 
 
HOW TO USE THEM 
 
 413 
 
 Closed Out 67^ Strings. — Staircases are sometimes fin- 
 ished with a close outer string, which prevents dirt or 
 wet falling into the well. Illustration No. 26 shows 
 the section, Fig. 1, and the elevation, Fig. 2, of a 
 moulding outer string. The dotted line at A indicates 
 a dowel hole for the balusters. Outer strings, whether 
 plain or moulded, are much stronger when formed in 
 
 Fig; I. Fig. 2. 
 
 NO. 26. 
 
 situ. This is best effected by fixing a reverse mould 
 at each side, then filling in the space from the top. The 
 top is finished by hand and the aid of a template. The 
 dowel holes are formed as already described. 
 
 Concrete Floors. — It has been mentioned that the 
 Romans, in the time of Julius Caesar, were in the habit 
 of constructing their floors and roofs, as well as their 
 walls, of concrete. According to an article in Archaeolo- 
 gia, the cementitious agent was pozzolana. The lime 
 
414 CEMENTS AND CONCRETES 
 
 was obtained by burning ' ' traverstine, ' ' The aggregate 
 usually consisted of broken tufa for walls, of broken 
 lava for foundations where great strength was re- 
 quired, and of broken pumice where lightness was es- 
 sential. The floors were generally constructed of large 
 slabs of concrete, supported on sleeper brick walls. 
 The upper surface was finished with a layer of finer 
 concrete and mosaic. The roofs were made flat, rest- 
 ing on brick pillars. The first known English patent 
 fireproof construction was obtained by one Dekins Bull, 
 in 1633 ; but as at that period patentees were not com- 
 pelled to disclose what their patents covered, no de- 
 scription of the materials and methods can be given. 
 Up to the middle of the eighteenth century fireproof 
 their great weight and cost, were seldom used. But 
 towards the close of that century cast-iron girders and 
 segmental brick arches were gradually coming into use 
 where strength was essential. Up to a century ago 
 plaster was largely employed as a floor material. In 
 floors usually consisted of brick arches, but owing to 
 1778 Earl Stanhope invented pugging for rendering 
 wooden floors fireproof. By this process fillets were 
 paled to the joists at about one-third of the height. 
 Laths were laid on the fillets and plastered above and 
 below with a coat of lime and chopped hay. The under 
 sides of the joists were then lathed and plastered in the 
 usual way to form the ceiling. About the early part of 
 the last century wrought iron joists were substituted 
 for cast iron girders. Fox & Barret's floor, designed 
 about 1830, was the first in which an attempt was made 
 to protect the exposed faces of the iron joists with a 
 fire-resisting material. Hornblower's floor is one of the 
 earliest for resisting the effects of fire» Iron, bricks 
 
HOW TO USE THEM 
 
 415 
 
 and plaster are chiefly used in the French and Ameri- 
 can systems. For the sake of simplicity and reference, 
 concrete floors may be divided into three kinds: (1) 
 
 Joist floors/' in which the concrete is laid slid be- 
 tween the joists; (2) ''Tabular floors," formed with 
 fireclay tubes or hollow lintels placed between the 
 joists and covered with concrete; (3) ^'Slab floors," 
 formed in one piece or slab. Portland, cement concrete 
 laid in situ on and between iron joists is extensively 
 used for fire-resisting structures. Cast concrete is used 
 for some parts of tabular floors. Cast concrete blocks 
 are used for the ceiling surface, and as a support for 
 the rough concrete floor surface. The blocks are hol- 
 low, and have male and female dovetails on the sides. 
 The ceiling surface of the floors and the outer surfaces 
 of the partitions are finished with a thin setting coat of 
 gauged putty or Parian. The chief objects of fire- 
 proof floors are to render each floor capable of resist- 
 ing the effects of fire, so that fire cannot be communi- 
 cated from one floor to another, and by making the 
 roof fireproof, to prevent the fire from spreading from 
 one compartment to another; to gain additional 
 strength, so as to avoid as far as possible lateral thrust 
 on the- walls, and to secure the building from attacks 
 and effects of both dry rot and damp. There have been 
 about a hundred patents for fireproof floors during the 
 past generation, of which about five or six survive. 
 
 Plaster Floors. — Plaster concrete, that is, plaster and 
 broken bricks, or similar aggregates, also neat plaster, 
 were at one time used largely for the formation of 
 floors. The use of plaster floors was common in some 
 districts, and up to a century ago^ the rough plaster, 
 known as ''floor plaster," was in general use where 
 
416 CEMENTS AND CONCRETES 
 
 gypsum was found in abundance. Plaster floors were 
 rarely used on the ground level, because they could not 
 resist moisture, which caused them to become soft and 
 retain the damp. They were principally used for up- 
 per floors. The gauged plaster was laid upon reeds. 
 These reeds were spread upon the tops of joists, and 
 over them was laid straw to keep the soft plaster from 
 percolating through the reeds. The floors were about 
 3 inches thick, floated fair, and finished the following 
 day. AVood strips were placed around the walls, and 
 drawn out when the plaster began to set, to allow for 
 ^he expansion of the plaster. The materials being so 
 light, the timbers were less in size and number than 
 those now in use. The joists were in some instances 
 3% inches by 2% inches, fixed wide apart, and sup- 
 ported by small beams about 4^/2 inches by 3^/2 inches, 
 The undersides between the joists were made fair by 
 plastering the reeds, but in the better class of work the 
 joists were covered with reeds, and held in position with 
 oak laths, and plastered. Bullock's blood was used to 
 harden the floors after they were dry. In some in- 
 stances they were coated with linseed oil to increase 
 their hardness. Their use is now practically super- 
 seded by Portland cement concrete. 
 
 Joist Concrete Floors. — For this form of floor the 
 concrete is laid between, over and under the iron joists 
 Beyond the supervision of the fixing of the centring 
 and the gauging of the materials, little skilled labor is 
 required. The rough concrete is laid between and 
 partly under the iron joists, which are fixed from 3 feet 
 to 5 feet apart, according to the span and strength of 
 the joists. The centring is supported, or rather hung, 
 by the aid of timber laid across the joists and secured 
 
HOW TO USE THEM 
 
 417 
 
 by bolts. The materials are generally Portland ce- 
 ment and gravel coke-breeze, clinkers and broken 
 bricks, gauged in the proportion of 1 part of matrix 
 to 5 of aggregate. Sand equal to one-third of the 
 bulk should be added. Coke-breeze is weak, light and 
 elastic, but combustible and porous. A mixture of 
 gravel and breeze in equal proportions is better than 
 either alone. The proportion of cement varies accord- 
 ing to the span and class of aggregate. All other 
 things being equal, the strength of concrete is influ- 
 enced by the strength of the aggregate, so that it 
 would take a greater proportion of cement to make 
 coke-breeze concrete equal in strength to a concrete 
 made with hard aggregate, such as granite, slag or 
 brick. The upper surface of this class of floor may 
 be finished with wood, tiles or fine concrete, as re- 
 quired. Joist concrete floors have been largely used. 
 This is principally owing to their supposed cheap- 
 ness, but it is more than probable that, in the event 
 of fire, they would be dear in the end, because the 
 lower part of the flanges are barely protected from the 
 effects of fire, as the concrete, being thin at these parts, 
 and also on a comparatively smooth surface, would 
 soon crack or scale off, and leave the flanges of the 
 joists exposed to the ravages of fire. They are also 
 more or less conductors of sound. Caminus concrete 
 cement is an excellent material for the construction 
 of fireproof ceilings and partitions. 
 
 Caminus Concrete Cement. — This material is specially 
 designed to produce a hard and practically indestructi- 
 ble concrete for the construction of fireproof floors and 
 walls. It is manufactured from a waste product, and 
 all inflammable material, such as coke-breeze, being en- 
 
418 CEMENTS AND CONCRETES 
 
 tirely dispensed with, the concrete is thoroughly fire- 
 resisting*. It is lighter and much cheaper than Port- 
 land cement concrete, and is perfectly free from ex- 
 pansion and contraction whilst setting. It can be man- 
 ufactured to set in a few hours, so that the centres 
 can be struck the day after the floor is laid. It can 
 be supplied in a ready aggregated condition, so that the 
 bags may be hoisted direct to the floor where the con- 
 crete is being laid, and gauged on the floor, thus sav- 
 ing a great amount of waste, and also labor in handling, 
 mixing and laying. 
 
 Concrete Floors and Coffered Ceilings. — A method 
 was patented by E. Ransom for decreasing quantity of 
 material and yet obtaining equal strength in floors. The 
 floor is divided by a series of beams at right angles 
 to each other, so as to form a series of coffers in the 
 ceiling. For instance, for a floor 12 inches thick, the 
 floor proper would be about 4 inches thick, and beams 
 about 3 inches thick and 8 inches deep — a rod of twist- 
 ed iron being placed in the centre of the thickness, and 
 near the lower surface of the beams. The beams are 
 generally about 2 feet 6 inches from centre to centre. 
 The method of construction is as f ollov/s : First, form 
 a platform or centring; on this a series of core boxes 
 2 feet 3 inches is placed, 3 inches apart, so as to form 
 a 3-inch beam. The core boxes must be tapered and 
 their upper edges rounded, so that they will draw when 
 the centring is struck. The size of the core boxes may 
 be altered to suit the size and requirements of the 
 floor. With regard to the iron bars, the inventor says : 
 ^^It is of vital importance for the strength of the struc- 
 ture that the iron bars be placed no higher in the beam 
 than calculated for; that the longitudinal centre of 
 
HOW TO USE THEM 
 
 419 
 
 these bars should be at the lowest point ; and it is ad- 
 visable that the bars curve upwards slightly and uni- 
 formly each way from the centre to the ends, so that 
 the ends are from 1 to 3 inches higher than the cen- 
 tres. By preparing the concrete bed on a correspond- 
 ing curve, the natural sag of the bar, as it is being 
 handled to its place, gives all the requisite facility to 
 accomplish this purpose. No crooked or irregular 
 t^visted iron must be used; otherwise, when the strain 
 comes upon it, it will perforce straighten and lengthen 
 out, and weaken the structure in so doing. After 
 placing the iron, the rest of the concrete is tamped in 
 place, and the whole made to form a monolithic block. 
 It is of vital importance that no stop be made in the 
 placing of concrete from the time the beam is begun 
 until the thickness of the beam is in place and a 
 through joint' is made. The web and the thickness 
 must be one solid piece of homogeneous concrete." 
 
 Combined Concrete Floors and Panelled Ceilings, — A 
 combined floor and panelled ceiling may also be formed 
 in concrete. This is executed as follows : First, form 
 a level platform or centring, and on this fix the re- 
 verse plaster mould, run and mitred, according to the 
 design of the ceiling. The intervening panels are then 
 made up with framing, and the concrete filled in the 
 usual way, and when set the centring and reverse 
 mould are removed, and the ceiling cleared off. If de- 
 sired, a finely finished and smooth white surface may 
 be obtained by coating the surface of the moulds and 
 panels with firmly gauged Parian, or other white ce- 
 ment, until about % inch thick, and when this is firm 
 (but not set), the rough concrete is deposited in layers 
 and tamped to consolidate the concrete, and unite it 
 
420 CEMENTS AND CONCEETES 
 
 with the white cement. The surface may also be fin- 
 ished with fibrous concrete. The method of doing this, 
 also for carrying out the above white cement process, is 
 described in Fibrous Concrete." 
 
 Concrete and Wood. — Concrete floors finished with 
 flooring boards require special care to prevent damp or 
 dry rot. There are various methods in use for fixing 
 and keeping the flooring boards from contact with the 
 rough concrete, one way being to fix wood fillets to the 
 joists by means of wedges or clamps. Another way 
 is to embed wood fillets or fixing blocks in the rough 
 concrete, leaving them projecting above the level of the 
 iron joists, to give a bearing and fixing points to the 
 flooring boards; or fine coke-breeze, concrete or plas- 
 ter screeds, may be laid at intervals on the rough 
 concrete, onto which the boards are nailed. Fixing 
 blocks, concrete or plaster screeds, are preferable to 
 wood fillets, as they do not shrink or rot, and will 
 better resist fire. All these methods leave intervening 
 spaces between the concrete and the boards, and unless 
 thoroughly ventilated, they harbor vermin, dirt and 
 stagnant air. Unless the wood is thoroughly seasoned, 
 and the boards grooved and tongued, dust and ef- 
 fluvia will find egress through the joints. A portion of 
 dust and water when sweeping and washing the floors 
 also finds egress through the joists; and as the concrete 
 will not absorb the water, or allow the dust to escape, 
 they accumulate and become unseen dangers. These 
 sanitary evils may be obviated, or at least reduced to 
 a minimum, by laying the boards direct on the con- 
 crete. This not only, forms a solid floor with no inter- 
 spaces, but admits of thin boards being used with as 
 much if not greater advantage than a thick board. 
 
HOW TO USE THEM 421 
 
 There is no uneven springing between the joists, which 
 causes friction and opening of the joints^ and the whole 
 thickness is available for wear. There is also less total 
 depth of floor, consequently less height of building and 
 general cost. Another important advantage of a solid 
 floor is that it will resist fire better than one with hol- 
 low spaces. It is here that the sponginess and elasticity 
 of coke-breeze concrete as a top layer is of special 
 service, and where it may be utilized with advantage. 
 Owing to its being able to receive and retain nails, the 
 boards can be nailed at any desired place. Wood 
 blocks for parquet floors can also be bedded or screwed 
 on the concrete surface. Flooring boards will lie even 
 and solid on this surface, and if a thin layer of felt or 
 slag-wool be spread on the concrete before the boards 
 are laid, a firm and noiseless floor is obtained. Slag- 
 wool is an imperishable non-conductor of heat, cold 
 and sound, and it will not harbor vermin. If the work 
 is in humid climate, the coke-breeze surface when dry 
 should be coated with a solution of tar and pitch, to 
 prevent atmospheric moisture being absorbed by the 
 porous coke-breeze. 
 
 Concrete Drying. — To prevent dry rot It is of the ut- 
 most importance that the concrete should be thoroughly 
 free from moisture before the flooring boards are laid 
 and fixed. The drying of concrete is a question of 
 time, which depends upon the amount of water used 
 for gauging, the thickness and the temperature. It 
 may take from three days to three weeks or even three 
 months. The drying can be accelerated by directing 
 currents of hot air on the lower surface, or by laying 
 some absorbent material, such as dry sawdust or brick 
 dust, on the upper surface, As soon as the surface 
 
422 CEMENTS AND CONCRETES 
 
 moisture is absorbed, or the dry material has no further 
 absorbent power, it should be removed to allow the 
 mass to be air dried. Another way is to lay the floor 
 in two coats, and to allow one coat to dry before the 
 other is laid. For instance, if the floor is to be 6 
 inches thick^ the first coat is laid with rough, but 
 strong* concrete, the aggregate being the best available ; 
 but taking gravel and coke-breeze to be the most 
 plentiful, it will be best to assimilate and combine the 
 good qualities of each to equalize their defects by mix- 
 ing them in equal proportions. If brick is plentiful, 
 and broken to properly graduated sizes, it will give 
 better results than gravel or breeze. The mixed ag- 
 gregate is gauged 5 parts to 1 of cement, and laid 4^/2 
 inches thick, and gently but firmly beaten in situ, the 
 surface being left rough to give a key for the second 
 coat. The second coat is not laid until the first is 
 dry, and consists of one part cement to 5 of sifted and 
 damped coke-breeze, gauged stiff, and laid 1% inches 
 thick, beaten in situ, ruled level, and any ridges being 
 laid fair with a long hand-float. The moisture of the 
 second coat, by reason of the density of the first coat, 
 will only be absorbed to a small degree, while the 
 greater portion will be taken up by the atmosphere, 
 and enable the combined coats to dry sooner than if 
 laid in one. The first coat should be laid as soon 
 as the roof is on, so as to give all possible time for it 
 to dry^ and the second coat to be laid and dried before 
 the flooring is laid. When coke-breeze is not avail- 
 able for the second coat, use soft brick, broken to pass 
 through a 3-16-inch sieve. The method of laying floors 
 in two coats is only given as an alternative plan, and 
 as an example of a process used in some parts. Greater 
 
HOW TO USE THEM 
 
 423 
 
 strength, as a whole, and more perfect cohesion be- 
 tween the two coats, is obtained by laying the second 
 coat as soon as the first is laid, or at least while it is 
 green. 
 
 Concrete Slab Floors. — The term, slab floor, is applied 
 to a concrete floor form.ed in situ, and in one piece or 
 slab. It must not be confounded with slab pavements, 
 which are constructed with a number of small cast 
 slabs. Slab floors are usually made without exterior 
 iron supports, but in a few instances iron T pieces or 
 bars have been used as internal supports. Bearing in 
 mind the lasting properties of the old Roman slab 
 floors, and the enormous strength of the modern exam- 
 ples at home, which are unsupported by iron, and are 
 practically indestructible, it seems strange that they are 
 not in more general use, and that for some inexplica- 
 ble reason preference is given to shrinking, rotting 
 and combustible floors^ composed of poor iron and tim- 
 ber instead of the best work and material, which, if a lit- 
 tle deai^er at first, is infinitely superior and vastly 
 cheaper in the long run. The great sanitary advan- 
 tages and fire and damp resisting powers of concrete 
 slab floors are the highest known. The construction of 
 slab floors is simple, and similar in many respects to 
 that already described for stair landings and ordinary 
 concrete and joist floors. There are several methods 
 of supporting the floors, the first and most common 
 being to leave a sand course or to cut a horizontal chase 
 in the walls to receive the ends of the floors. The 
 second is to lay the floors when the walls are floor 
 high, and build the higher walls on it when set. This 
 method, while making sound work, is not always prac- 
 ticable or convenient, owing to the delay in building 
 
424 CEMENTS AND CONCRETES 
 
 while waiting for the floors to set. The third method 
 is to build corbelled ledges in the walls, so as to carry 
 the floors. The centring for slab floors should be per- 
 fecth^ rigid, water-tight and slightly cambered towards 
 the ceiling centre. This camber gives more strength 
 to the floor, and lessens liability to crack when remov- 
 ing the centring. If joists are not used, the centring 
 is supported on Avall boards and centre struts. An- 
 other way which gives great additional strength is to 
 form the centring level, but having all the edges at the 
 wall rounded off, so as to form the floor like an in- 
 verted sink or tray. The horizontal chases in this case 
 should be made wider than the thickness of the floor to 
 allow for a thickness of rim. The extra width of chase, 
 which may be one or two bricks thick, according to the 
 width of span, is made below the centring or line of 
 ceiling, the angles being coved by rounding the edges 
 of centring. The coved rim gives greater strength 
 with a less thickness of floor. The cove may be left 
 plain or used for a cove for a plaster cornice, or rough- 
 ened and used as a bracket for the same purpose. The 
 expansion of concrete floors having large areas, or 
 where hot cement has been used, has been known to 
 disturb the walls^ causing cracks and displacement of 
 brick and stone work. This may be prevented by 
 isolating the floor ends from the walls. This is done 
 by forming expansion partitions or linings in the chases, 
 the linings being composed of slag, felt or wood shav- 
 ings, straw, reeds or other compressible material. The 
 chase should be sufficiently deep to allow for a com- 
 pressible lining about IV2 inches thick, and a fair bed 
 for the slab floor. Care must be taken to leave a few 
 half bricks solid at intervals, say from 3 to 4 feet 
 
HOW TO USE THEM 
 
 425 
 
 apart, to support the upper walls until the floor is set. 
 Compressible linings may be used for floors supported 
 on corbelled ledges; and when the expansion, and in 
 many cases subsequent contraction, has finally finished, 
 the linings can be taken out, and the vacant space 
 filled up with fine concrete, or utilized as a ground key 
 for cement skirtings. If girder or iron posts are iso- 
 lated from the walls by means of compressible linings, 
 the eff^ects of expansion and sound are limited. In 
 some instances a judicious use of iron may be made. 
 For instance, large areas may be divided with three or 
 four rolled iron joists, so as to form shorter spans or 
 smaller bays. Joists tend to bind the walls together, 
 and to serve as scaffold bearings for building the upper 
 parts of walls. They may also be used for hanging 
 the centring on instead of strutting, or as aids to ihe 
 strutting. Joists may also be used as integral sup- 
 ports at unsupported ends of concrete floors. They 
 should be so fixed that the lower flanges are not less 
 than 1 inch above the lower surface of the concrete. 
 The whole strength of iron is brought more fully into 
 use by fixing it near the lower surface. If fixed near 
 the centre, or at the axis of neutral stress, a correspond- 
 ing part of the strength is comparatively of little 
 value„ 
 
 Construction of Slab Floors. — Portland cement as a 
 matrix is indispensable. The unequal nature of gravel 
 and col^e-breeze renders them unfit and unsafe aggre- 
 gates for this class of work. Broken brick being cheap, 
 and obtainable in most districts, affords a ready aggre- 
 gate, and may be used with safety and success. In 
 ordinary cases of concrete construction, the whole 
 thickness is usually made with one rate of gauge ; but 
 
426 CEMENTS AND CONCRETES 
 
 for slab floors covering large areas, and unsupported 
 by iron or other supports, exceptional strength is re- 
 quired. Stronger results are obtained by making up 
 the whole thickness with different rates of gauge. Tak- 
 ing the usual gauge for floors as from 4 to 5 parts of 
 aggregate to one of cement, and used for the whole 
 thickness, it gives an unequal strength, a part of which 
 is comparatively of little use, especially at the neutral 
 axis; but if the cement is divided so as to form an 
 ordinary coat in the centre, and stronger coats at the 
 upper and lower surfaces at the points of greatest 
 strain, the upper being compressive and the lower ten- 
 sive, a better and more accurate arrangement of 
 strength and allowance for disposition of strains is ob- 
 tained. The additional strength at the proper places 
 is obtained not only by the use of additional cement, 
 but by the method of construction, which enables the 
 same quantity of cement as gauged for the usual rate 
 for forming the whole thickness in one coat to 
 be used more profitably. Take the section of 
 an iron joist as an example; this gives divided 
 yet united strength, which sounds paradoxical, 
 but is true. The flanges sustain the greatest 
 strains, and the web comparatively little. With con- 
 crete, the strong coats at the upper and lower surfaces 
 represent the flanges, and the ordinary coat the web. 
 As already stated, the increased and profitable dis- 
 tribution of strength is obtained by the method of con- 
 struction. For instance, take a slab floor 20 feet by 
 14 feet and 12 inches thick, without iron joists or other 
 supports, and intended to carry a safe load of 2V2 cwt. 
 per superficial foot, in addition to its own weight of say 
 1 cwt. per square foot. This floor is laid in three coats, 
 
HOW TO USE THEM 
 
 427 
 
 the first composed of 1 part cement and 2 of fine broken 
 bricks gauged stiff, and laid 2 inches thick ; the second 
 composed of 1 part cement and 6 of coarse broken 
 bricks gauged stiff and laid and rammed 8 inches thick ; 
 and the third composed of 1 part cement and 2 of fine 
 broken bricks gauged stiff and laid 2 inches thick. 
 If the upper surface is intended for hard frictional wear 
 a slight difference is made in the gauge and materials. 
 The first coat is composed of 2 parts of cement and 5 of 
 fine broken bricks gauged stiff and laid 2 inches thick ; 
 the second of 1 part cement and 6 of coarse broken 
 bricks gauged stiff and laid and rammed till 8 inches 
 thick ; and the third coat composed of 1 part cement and 
 2 of fine crushed slag or granite. It will be seen that 
 this constructive method gives the desired positions of 
 strength^ and the total quantity of cement in the united 
 gauges is 1 part to 4, and up to 5 parts of aggregate. 
 The fine broken bricks should be passed through a 1/2- 
 inch sieve, and the coarse through a 2-inch screen, 
 taking care that the latter contains a greater quantity 
 of the smaller pieces than of the larger. It must be 
 clearly understood that the second coat must be laid 
 before the first is set ; also that the third is laid before 
 the second is set, so as to ensure perfect cohesion be- 
 tween each coat, and the absolute homogeneity of the 
 whole mass. 
 
 Hollow Floors. — Greater lightness in concrete floors is 
 obtained by the use of concrete tubes. If the tubes are 
 placed apart and in the centre of the floor thickness, 
 a hollow homogeneous concrete slab is formed. The 
 vertical divisions between the tubes connect the upper 
 and lower coats^ as with a web of a joist connecting the 
 upper and lower flanges. The method of construction 
 
428 CEMENTS AND CONCRETES 
 
 is simple and expeditious. For example, for a slab 
 floor 10 inches thick, first lay a coat 2 inches thick of 
 the stronger and finer concrete, as described for the 
 12-inch slab floor, and when this is firm lay 5 or 6- 
 inch tubes from wall to wall. Bed the sides with rough 
 concrete, and lay another row of tubes parallel with the 
 first row and about 2 inches apart, and so on until the 
 floor area is covered; then make up interspaces with 
 rough concrete till level with the upper surfaces of the 
 tubes, and then cover this with a coat of fine concrete 2 
 inches thick. Concrete tubes or common earthenware 
 drain pipes may be used. Half-circle pipes, laid on 
 their side edges, may be used to save concrete and 
 weight in joist floors, etc. 
 
 Concrete Roofs. — Concrete roofs require special care 
 to render them watertight. Subsidence in the brick 
 work of new buildings is often the cause of cracks on 
 concrete roofs. The roof should have a good camber, 
 to give greater strength and allow for the fall of wa- 
 ter to the outer edges. The rough coat should be laid 
 and well consolidated by ramming or beating, and then 
 left for seven days (the longer the better) before the 
 topping is added. The upper coat should be strongly 
 gauged with fine aggregate, as in Eureka." If possi- 
 ble, the topping should be laid in one piece. If the 
 area is too large to be laid and finished in one piece, 
 the joints of the bays should overlap. This is done 
 by rebating the screed rules, so as to allow one-half of 
 topping thickness to go under a part of the rule and 
 form an underlap or ledge about I/2 inch wide, and 
 when the adjoining bay is laid an overlapped but level 
 joint is the result. Eoofs exposed to the sun's heat 
 should be kept damp for several days after being laid, 
 
HOW TO USE THEM 
 
 429 
 
 as joints are affected by the heat as well as by deflec- 
 tion of centring or subsidence of walls. Compressible 
 linings or wood strips should be used round the walls 
 to counteract any expansion. All concrete roofs should 
 have a cement skirting 6 inches high and 1 inch thick 
 well keyed into the walls. If linings are not used when 
 the topping is laid, the topping should be turned up on 
 the walls, so as to form a rim, to prevent water get- 
 ting between the roof and the walls. Greater heat and 
 damp-resisting powers are obtained by laying the up- 
 per surface with ^^-inch thick coat of special concrete, 
 composed of 1 part of Portland cement, I/2 part of 
 slaked lime and 1 part of firebrick dust. This should 
 be consolidated with a hand-float, and finished fine and 
 close with a trowel. 
 
 Notes on Concrete, — When calculating the strength of 
 floors, stairs, etc., the following facts should be borne 
 in mind: Portland cement, when new, is too hot; sets 
 more rapidly and expands more than old cement. The 
 finest ground cement is the best and strongest. The 
 time in setting, and in which the maximum strength is 
 attained, varies according to the age of the cement, the 
 quantity of water used, and the mode of gauging and 
 the mean atmospheric temperature. The maximum 
 strength of a briquette of mature cement is maintained, 
 while one of new cement ^^goes back." A briquette of 
 matured cement will stand a tension strain of 550 
 pounds per square inch, and a crushing weight of 6,000 
 pounds per square inch. A briquette of neat cement is 
 more brittle than one of concrete. Briquettes mature 
 more rapidly than thick slab floors. The adhesive 
 strength of Portland cement is about 85 pounds per 
 square inch. The adhesive strength increases more 
 
430 
 
 CEMENTS AND CONCEETES 
 
 rapidly than the cohesive. A mass with a surface 
 large in proportion to its volume sets more rapidly than 
 a mass with a small area in proportion to its volume. 
 Masses subject to pressure set more rapidly and attain 
 greater hardness than masses not so pressed. The 
 average compressive strength of concrete is about eight 
 times its tension strength. The proportion of com- 
 pressional and tensional strength varies according to 
 the quality and quantity of the aggregate. The strength 
 of concrete depends greatly on the proportion of the 
 matrix and aggregate ; also on the strength of the lat- 
 ter. As regards bricks, it must be remembered that 
 there is a wide difference between the tensile strength 
 of hard, well-burnt bricks and soft stocks. No bricks 
 are so strong as cement, the best kinds being about 
 one-fourth the strength of neat cement. Taking the 
 gauge as one part of cement to 4 of broken brick, the 
 strength of the concrete will be about tv/o-fifths of neat 
 cement, but for safe and practical calculations it will 
 be best to take the strength as one-fourth of neat ce- 
 ment. Square slabs are stronger than rectangular 
 slabs. Slab floors being homogeneous throughout, the 
 whole weight is a dead weight, and consequently there 
 is no thrust on the walls. With regard to the live load 
 or weight which fl.oors should be constructed to carry, 
 some difference of opinion exists. Hurst sa^^s that for 
 dwellings l^y4 cwt, public buildings % cwt. and ware- 
 houses and factories 2^/^ cwt. are safe calculations. 
 Others assert that for domestic buildings 1 cwt. per foot 
 would be ample for all contingencies. An American 
 authority states 40 lbs. is sufficient for ordinary pur- 
 poses. The following table shows the results of tests 
 
HOW TO USE THEM 
 
 431 
 
 of slab floors made without iron. The slabs were sup- 
 ported all round, and uniformly loaded with bricks. 
 
 Test of Slab Floors. 
 
 No. 
 
 Length 
 between 
 Sup- 
 ports, 
 feet. 
 
 Breadth 
 between 
 Sup- 
 ports, 
 feet. 
 
 Thick- 
 ness, 
 feet. 
 
 Age in 
 Days. 
 
 Breaking 
 Weight, in 
 cwt. per 
 sq. ft. 
 
 Weight of 
 Slab, in 
 cwt. per 
 sq. ft. 
 
 Total 
 Breaking 
 Weight, in 
 cwt. per 
 sq. ft. 
 
 1 
 
 14.5 
 
 6.75 
 
 .5 
 
 7 
 
 3. 
 
 .54 
 
 3.54 
 
 2 
 
 
 
 
 14 
 
 2.76 
 
 
 3.30 
 
 3 
 
 
 (< 
 
 
 21 
 
 8.88 
 
 
 9.42 
 
 4 
 
 
 13.5 
 
 
 7 
 
 1.07 
 
 
 1.61 
 
 5 
 
 
 6.75 
 
 
 14 
 
 2.51 
 
 
 3.05 
 
 6 
 
 
 
 
 21 
 
 2.84 
 
 
 3.38 
 
 Cast Concrete. — Innumerable patents have been ob- 
 tained for a combination of materials, also moulds for 
 the construction of artificial stone. Among the many 
 that may be mentioned is Mr. Ranger's system. He ^ 
 obtained a patent in 1832 for artificial stone formed 
 with a lime concrete. The aggregate consisted of 
 shingle, broken flints, mason's chippings, &c. The in- 
 ventor stated that the best results were obtained by 
 using 30 lbs. of an aggregate of a siliceous or other 
 hard nature, 3 lbs. powdered lime, and 18 ozs. boiling 
 water. No more of *the materials were gauged at the 
 time than were sufficient to fill one mould, as the boil- 
 ing water caused the concrete to set very rapidly. This 
 material, after fifty years' exposure is still sound and 
 shows no sign of decay. No artificial stone equals, far 
 less excels, the strength and durability, sharpness, and 
 evenness of Portland cement concrete. This form of 
 artificial stone is now extensively used as a substitute 
 
432 CEMENTS AND CONCRETES 
 
 for natural stone, for window heads, string courses, 
 sills, columns, copings, keystones, and many other archi- 
 tectural, constructive, and decorative features. Fig- 
 ures, animals, bas-reliefs, capitals, panels, can be made 
 in fine concrete with all the relief, undercut, and fine 
 detail which distinguishes high-class from inferior 
 work. Cast work has the advantage over in situ work 
 that any defect can be detected previous to fixing. The 
 methods of moulding and casting various works are 
 given in the following pages. 
 
 Concrete Dressings, — Architectural works, especially 
 large or plain parts, are generally cast in wood moulds. 
 If there are ornamental parts in the blocks, a combina- 
 tion of wood and plaster, and sometimes gelatine, is 
 used for the moulds ; wood for the main or plain parts, 
 plaster for circular or moulded parts, and gelatine for 
 undercut parts. The plaster or gelatine, as the case 
 may be, is screwed on or let into rebated parts of the 
 wood. Ornamental parts are sometimes cast separately, 
 and then fixed on the main cast. They may also be 
 cast separately and laid into the main mould (face 
 inwards), and the whole is cast together in a somewhat 
 similar way to that described for '^bedded enrich- 
 ments'' in fibrous plaster cornices. 
 
 Considerable skill and ingenuity has been displayed 
 in the construction of wood moulds for casting concrete 
 blocks for architectural purposes. Many methods have 
 been emploj^ed for fixing the sides and ends together, 
 and also to the bottom of the mould, leaving one or 
 more parts unfixed to facilitate the release of the cast. 
 The primitive method is to fix the various parts of the 
 mould with screws. This is a slow and unreliable 
 process, as the continual screwing and unscrewing for 
 
HOW TO USE THEM 
 
 433 
 
 each cast soon wears the screw-holes, and the sides be- 
 come loose and out of square, causing the casts to get 
 out of their true form. Hinges, also hooks and eyes, 
 have been used for the same purpose, but they are 
 liable to the same defects as the screws when subject 
 to long use. 
 
 —Wedge Mould for Casting Blocks, Mouldes 
 Lintels, Sec, 
 
 NO. 27. 
 
 Thumbscrews to fit into iron sockets are also used, 
 but they are too expensive for ordinary work, and are 
 unsuitable for small moulds. One of the most simple 
 and reliable methods is the ^Svedge mould," invented 
 by an architect. It is easily made, and expeditious in 
 working. Even after long and constant use, the casts 
 are alwa^^s accurate in form and size. The wedges and 
 the rebated ends allow the various parts to be correct- 
 ly fixed and held in position. Illustration No. 27 shows 
 the method of construction. The various parts are 
 
434 
 
 CEMENTS AND CONCRETES 
 
 named, and the sketch is self-explanatory. When the 
 moulds are extra deep, it is necessary to make two or 
 more sets of tenons and wedges at each angle. When 
 there are a large number of casts required the mould 
 ends are strengthened by binding the projecting ends 
 with hoop iron. This method has been adopted for 
 casting a lot of blocks. Illustration No. 28 shows two 
 useful kinds of moulds. Fig. 1 is a simple form of 
 mould adapted for plain blocks, caps, lintels, &c. A, A, 
 are the sides, which are grooved into the ends B, B, and 
 
 F^ig. I. Fig. 2. 
 
 NO. 28. 
 
 held together by the bolts and nuts, C, C, two on each 
 side. The bolts may be about % inch diameter, with 
 a good-sized square-head at one end, and a washer and 
 nut at the other. This^ having no bottom, is termed a 
 bolted frame mould. It should be laid on a bench or 
 moulding board before the cast is filled in. Fig. 2 is 
 a section of a combined wood and plaster mould on the 
 wedge principle, adapted for casting a strong course 
 moulding. A is a moulding board, II/2 inches thick, 
 formed with two or more boards; a is one of two or 
 more cross ledges, 1 inch thick, on which A, the ground, 
 is nailed, B is a width board, 1 inch thick, which is 
 
HOW TO USE THEM 
 
 435 
 
 nailed on to A. This gives a point of resistance to the 
 plaster piece G and the side board G. D is a side board 
 on which E is screwed. E forms the sloping part of 
 the weathering. F is one of two or more vertical 
 wedges which hold D E in position. The sockets for 
 the wedges F are made between the cross ledges, so 
 that the wedge will project below the ground A. This 
 allows the wedges to be more easily driven out when 
 the cast is set. G is the back or plain side board. H 
 is a fillet, 1% inches square, screwed on to the ground 
 A. I and J are two folding wedges, or, in other words, 
 wedges driven in opposite directions. These hold G 
 in position. Two or more of these folding wedges are 
 required, according to the length of the mould. The 
 same remarks apply to the vertical wedges F. The lat- 
 ter form of wedge is only giA^en as an alternative. The 
 end pieces are held in position by dropping them into 
 grooves in a similar way as shown in the previous fig- 
 ure, with the exception that the grooves are cut in the 
 sides instead of the ends. K is a gauge rule which is 
 used for ruling the upper surface of the cast fair. This 
 may also be done by working a straight-edge longi- 
 tudinally. The dotted line at L, the concrete, indicates 
 the wall line. The level part of the weathering up to 
 this line, or if splayed from the outer member of this 
 line, must be finished smooth to allow the water to run 
 freely off. When the cast is set, the wedges are with- 
 drawn, and the sides and ends released. The cast is 
 then turned over on its back end or top side on a board, 
 and then the plaster piece and the wood ground is taken 
 off. If the cast is green, it should be turned over on 
 old sacks or wet sawdust, so as to protect the arrises, 
 and avoid fractures. 
 
436 CEMENTS AND CONCRETES 
 
 Illustration No. 29 shows a method commonly 
 adopted for constructing moulds for sills and copings. 
 Fig. 1 is the section of a mould for a window sill. A 
 is the moulding board, made with two or more pieces, 
 each 114 inches thick; a is one of two or more cross 
 ledges, made with 1 inch stuff, on which A is nailed. B 
 is the width board, made of % inch stuff, nailed on to 
 A. C is a block, 1% inches thick, which is nailed on 
 to B. These blocks are placed about a foot apart, or 
 so that they will carry the lining D, 1 inch thick. A 
 
 Fig: I. Fig. 2. 
 
 Fig. I.— Section of Mouli> for Casting Sills. 
 Fig. 2.— Section of Mouli)_^for Casting Coping. 
 
 NO. 29. 
 
 groove or an iron tongue E is made in B, and a piece 
 of thick hoop iron or iron bar is placed loosely in the 
 groove before the cast is filled in. F is a fixed side, 
 11/4 inches thick. G is a fillet, inches square, nailed 
 on to F, and screwed on to moulding board A. H is a 
 loose side, I14 inches thick, on which the fillet I is 
 nailed. J is one of two or more clips, which turn on 
 a screw, and are used to hold the loose side H in posi- 
 tion. These clips are made and used in the same way 
 as described for fibrous slabs. As compared with 
 wedges, clips are always in position ready for use, are 
 
HOW TO USE THEM 
 
 437 
 
 not liable to be mislaid, and when the fillets are fixed 
 on to the side pieces, the clips keep the sides frona 
 rising as well as expanding. K is a throating or water 
 groove, which is formed in the concrete L, with a rule 
 having a rounded edge. Two blocks, dished at the 
 inner ends, must be fixed one at each end of the mould, 
 so as to form a stool or bed for the superstructure. The 
 position and form of the groove is obtained from sink- 
 ings cut in the end pieces of the mould. The end pieces 
 are held in position by grooves cut in the side pieces 
 in a similar way, as already described, with the excep- 
 tion that the grooves are cut in the side pieces, instead 
 of the end pieces. AA^hen setting out the mould, an 
 extra length must be allowed for the side pieces for the 
 grooves. A part of the upper surface of the cast (be- 
 ing the part which projects beyond the line of wall) 
 must be finished fair by hand at the same time as form- 
 ing the water groove. This must be done while the cast 
 is green. When the cast is released from the mould, 
 the iron tongue will be found firmly embedded in the 
 concrete. Fig. 2 is a section of a wood mould adapted 
 for casting wall copings. A is the ground of a mould- 
 ing board, which may be made of l^/i-inch stuff, and in 
 2 or more widths ; a is one of two or more cross ledges, 
 1 inch thick, on which A is fixed. B, B, are blocks 
 about 114 inches thick, placed about 1 foot apart. C, 
 C, are linings, 1 inch thick, nailed to B, B. D is a 
 fixed side, I14 inches thick. E is a fillet, II/2 inches 
 square, fixed to D, and then screwed on to A. F is a 
 loose side, 1^/4 inches thick, on which is nailed the fillet 
 G, 11/2 inches square. This strengthens the sides and 
 affords the fixing point for the clip H. The water 
 grooves I, I, and the hollowed part in the middle of the 
 
438 CEMENTS AND CONCRETES 
 
 concrete J (made to save materials in weight) are 
 worked from the end pieces of the mould, which are let 
 into the grooves^ as described in the previous diagram. 
 If the moulds are deep, wood or iron clamps may be 
 fixed across the sides to keep them in position, as shown 
 by K. The moulding boards in this and the previous 
 figures, if strongly made, can be used for a variety of 
 similar purposes. When introducing cast instead of 
 run moulded work, I used iron and zinc plates to 
 strengthen and make more durable plain surfaces on 
 wood moulds ; but owing to the expense and trouble in 
 fixing the plates to the woodwork, they were aban- 
 doned, and by using a better class of wood, and in- 
 durating the surface of the mould with hot paraffin 
 wax, sharp and clean casts were more cheaply pro- 
 duced. Cast-iron moulds may be used where there is 
 a large number of casts required. They may also be 
 advantageously used for stock designs, such as plain 
 moulded balusters. Wood moulds are rendered more 
 durable and impervious to wet by brushing them with 
 hot paraffin wax, and then forcing it into the wood by 
 ironing with a hot iron. The use of paraffin wax and 
 oil has already been described. 
 
 Mouldings Cast '^In Situ/^ — Casting cornices, cop- 
 ings, &c., in situ is now frequently employed for con- 
 crete. The advantages of this system over shop cast 
 work, are, that the work is readily done, and the cart- 
 age or moving from the workshops to the building, and 
 the fixing, are dispensed with. 
 
 Illustration No. 30 shows the method of constructing 
 and fixing various kinds of casting moulds for in situ 
 work. 
 
 Fig. ] shows the section of a cornice, casting mould, 
 
440 CEMENTS AND CONCRETES 
 
 and supporting bracket. Wood moulds are generally 
 used for small or plain mouldings, but where the profile 
 is undercut or of an intricate nature, a plaster mould 
 is preferable, as it is easier and cheaper to construct a 
 plaster mould than cut the irons which are necessary 
 for a wood mould for a special design. Fibrous plaster 
 moulds may be used for this class of work, but to illus- 
 trate another method a combined . wood and plaster 
 mould is given. M is a moulding board to strengthen 
 the plaster profile, and on which it is run. The board 
 may be made in two or more pieces, each about 1 inch 
 thick, and in width according to the depth of the mould- 
 ing, and in length as required, the whole being held 
 together by cleats H, which are nailed about 3 or 4 feet 
 apart. Broad-headed nails are then driven in at ran- 
 dom, leaving the heads projecting, to give a key for 
 the plaster profile P. The profile is then run with a 
 reverse running mould. It will be seen that this profile 
 is undercut, therefore a loose piece L is required to 
 enable the mould to draw off the moulding. The re- 
 verse mould and loose piece are constructed iu the same 
 way as described under the heading of ''Reverse Mould- 
 ings.'^ It may be here remarked that it is sometimes 
 useful to have an ''eye" inserted in the loose piece to 
 give a better hold for the fingers when taking the loose 
 piece off the moulding. The eyes are made by twisting 
 a piece of strong wire round the handle of a tool bruch, 
 leaving one end in the form of a ring, and the other 
 bent outwards so as to form a key. The eyes are fixed 
 about 3 or 4 feet apart, the fixing being done by cut- 
 ting a hole in the loose piece and bedding the shank of 
 the eye with plaster, and then cutting a slot in the 
 main part of the mould to receive the ring of the eye 
 
HOW TO USE THEM 
 
 441 
 
 as shown at E. The mould is held in position by the 
 bracket B, fixed 4 or 5 feet apart. The mould is further 
 secured by the stay S, the other or inner end of the 
 stay is fixed on to the main wall. It will be understood 
 that a plaster mould for this purpose should be dry and 
 hard, and then well seasoned with linseed oil, or with 
 a hot solution of paraffin wax. After the mould is fixed 
 in position it is oiled, and then the concrete C is filled 
 in, taking care that the surface of the mould is first 
 covered with a thin coat of neat cement. The mould 
 may be oiled with paraffin oil; but if the mould is in- 
 clined to stick/' oil it with chalk oil/' i. e., paraffin 
 oil and French chalk, about the consistency of cream. 
 
 When the concrete is set, the brackets are removed, 
 and the mould taken off. The mould in this case would 
 draw in the line of the arrow A. The loose piece is 
 then taken off. It is here that the use of the eyes will 
 be found. Before removing the brackets it is advisable 
 to prop the mould, in case it may drop off and break 
 the fragile portions of the mould or parts of the cornice. 
 A heavy mould hanging in this position, especially if 
 the profile is flat, or in good working order, is apt to 
 drop, hence the necessity of props. If the mould clings, 
 or, as more generally called, ^'sticks fast,'' gentle tap- 
 ping with a heavy hammer will ease or spring it, and 
 allow it to be taken off. A heavy hammer is more ef- 
 fective in making the mould spring than a light ham- 
 mer, as the force required for a light hammer is apt to 
 injure the mould. This is why a heavy hammer with a 
 flat head is best for plaster piece moulding. 
 
 Eig. 2 is the section of a string moulding with the 
 casting mould and bracket. A chase is formed in the 
 brickwork to allow it to bond, and the joints and the 
 
442 CEMENTS AND CONCRETES 
 
 surface of the brickwork are cut out and hacked to give 
 a further key to the moulding. M is the mould (in this 
 case made of wood). The profile is drawn without any 
 undercut parts, so as to allow the mould to draw off in 
 one piece. B is the bracket^ and C is the concrete. The 
 same directions for casting Fig. 1 apply to this and 
 the other moulding here shown. A drip member, as 
 shown at the top member of both cornices, is generally 
 used for exterior mouldings^ to prevent the water run- 
 ning over the wall surface. 
 
 Fig. 3 is the section of a wall coping and the casting 
 mould. M is the mould, a similar one being used for 
 the other side. A mould for this purpose is best formed 
 with flooring boards about 1 inch thick, and fixing them 
 together as shown.- The drip D is readily formed by 
 sawing an inch bead through the centre, and nailing it 
 on the bottom. Two forms of brackets, B and B, are 
 here given. One is cut out of the solid, and the other 
 made of two pieces of wood nailed together. 
 
 Fig. 4 is the section of a casting mould for a saddle- 
 back coping. R is a quarter-round piece of wood fixed 
 in the angle of the mould to form a cavetto, which is 
 sometimes used in copings. D is an angular-shaped 
 drip, sometimes used in place of a circular one. T is 
 part of a template used for forming the saddle-back of 
 the coping. 
 
 Fig. 5 is the section of a mould for a coping with 
 splayed or chamfered angles. S is a triangular strip 
 of wood fixed in the angle and the top of the mould to 
 form the splays, and D is a circular drip. 
 
 Concrete mouldings that are deeply undercut or in- 
 tricate in profile may be cast in situ by the use of the 
 ''Waste Mould Process.^' 
 
HOW TO USE THEM 
 
 443 
 
 Modelling in Fine Concrete. — Figures of the humaii 
 and animal form, also emblems, trade signs, and build- 
 ings, are now being made in fine concrete. The work 
 may be executed in situ, or in the moulding shop, and 
 then fixed in position. For important works a plaster 
 model is first made, and placed in position, so as to 
 judge of the effect before committing it to the perma- 
 nent material. For this purpose the model is first 
 modelled in clay, and then it is waste-moulded, and a 
 plaster cast obtained. After the model is approved it 
 is moulded, and then cast in the fine concrete. The 
 material is composed of Portland cement, and a light, 
 but strong, aggregate ; and the cast is made in a similar 
 way to that described for casting vases. The material 
 may be colored as required to suit the subject. The 
 general method of executing figures ^^on the round'' 
 in fine concrete or Portland cement is to model the 
 figure direct in the cement on an iron frame, and then 
 to fix it in its permanent position. This is effected b}^ 
 first making a full-sized sketch of the proposed figure, 
 then setting out on this the form of the necessary iron- 
 work to serve as frame or skeleton to form an internal 
 support. This iron frame also forms a core to enable 
 the figure to be made hollow, and serves as a . permanent 
 support for thin parts and extremities of the figure. 
 The quantity, size, and form of the iron frame is regu- 
 lated by the size, form, and position of the figure. For 
 instance, if the model of a full-size lion is required, first 
 make a rectangular frame to suit the feet of the lion 
 and the base on which the figure stands. The .base 
 frame is made of iron bars, ly^ inches wide by i/4 i^ch 
 thick, fixed on edge. Then set out four leg-irons, and 
 connect them on the base frame, and then set out one 
 
444 CEMENTS AND CONCRETES 
 
 or two body-irons, and connect them with the leg-irons. 
 After this set out a looped piece to fit the contour of 
 the neck and head, and fix it to the body-iron. Now 
 set out the tail-iron. This is best formed with an iron 
 pipe, ^ and it should be made to screw on to the body- 
 iron. This allows the tail to be unscrewed when the 
 model is finished, and screwed on afi:er the model is 
 fixed in position, thus enabling the model to be more 
 freely handled, and with less risk of breakage when 
 moving and fixing in its permanent position. 
 
 Having made the frame, place it on a stout modelling 
 board, keeping the base frame from 1 to 3 inches above 
 the board, according to the depth of the base ; the frame 
 being temporarily supported with four pieces of brick 
 or stone. This is done to allow the base frame to be 
 enveloped with concrete. This done, fix wood rules, cut 
 to the depth of the base, on the board, so as to form 
 a fence on all sides of the base. Then fill in the base 
 with concrete ; and when this is set, proceed with the 
 coring out, so as to obtain a hollow model. 
 
 In order to decrease the weight of concrete figures 
 '^on the round,'' and to enable them to be more easily 
 handled and hoisted when fixing them in their perma- 
 nent positions, they should be made hollow. This is 
 effected by making a round skeleton frame with hoop- 
 iron, or with wire-netting, for the body, neck, and head, 
 and other thick parts. This metal skeleton must be 
 built on and securely fixed to the main iron frame. The 
 whole, or parts of the figure, may also be cored out with 
 shavings or tow, and held in position with tar bands or 
 canvas strips, dipped in plaster. Tow is an excellent 
 material for forming cores. By making up the inner 
 parts with dry tow^ and then dipping tow in plaster for 
 
HOW TO USE THEM 
 
 445 
 
 the outside coat, the core can be made to any desired 
 shape, and also leave the necessary thickness for the 
 concrete. To prevent the material slipping down by 
 its own weight, pieces of iron or wood, in the form of 
 crosses, are fastened with copper wire or tar rope to 
 the iron rods, which are used as single supports. These 
 iron or wood pieces must be fixed in all directions, and 
 in such a way that the material is held up by them. 
 For small extremities, such as fingers of human figures, 
 beaks of birds, fins of fishes, horns and tails of animals, 
 iron rods should be fixed on the main frame, and the 
 parts to be covered with cement must be notched or 
 bound at intervals with copper wire or tar rope. The 
 distance between the core and the finished face of the 
 figure is of course the actual thickness of the model. 
 This thickness may vary from 1 inch to 3 inches, or 
 even 4 inches at some parts. An actual thickness of 2 
 inches will be sufficient to give the requisite strength. 
 
 When the core is made, cover it with a coat of Port- 
 land cement and old lime putty, in the proportion of 3 
 of the former to 1 of the latter, and add sufficient tow 
 or hair to give tenacity. If there are open spaces in 
 the skeleton iron work, bridge them over with bits of 
 tiles and cement. The whole surface, after being coated, 
 must be well scratched with a nail, to give a key for 
 the roughing out coat. This scratched coat must be 
 allowed to set before proceeding with the actual model- 
 ling. The stuff for roughing out is composed of 2 
 parts of Portland cement and 1 part of fine aggregate. 
 Crushed bricks, stone, or pottery ware passed through 
 a sieve having a % inch mesh may be used as aggre- 
 gates. The finishing stuff is composed of fine sifted 
 Portland cement. The addition of a fifth part of old 
 
446 CEMENTS AND CONCRETES 
 
 lime putty to the cement makes the stuff more mellow, 
 and works freer and sweeter. The modelling is done as 
 described for in situ work. The finishing coat can be 
 colored to any desired tint, as already described. 
 
 Concrete Fountains^ — Fine concrete is an excellent 
 material for the construction of fountains. It is ob- 
 vious that a vast amount of cutting and consequent 
 waste of material is involved in the executing of foun- 
 tains, ^^on the round,*" when natural stone is employed. 
 Saving of material, and a corresponding reduction in 
 the cost, is effected by use of a material that can be 
 easily cast, and is at the same time durable and im- 
 pervious. These qualities combined are found in arti- 
 ficial stone composed of fine concrete. Being readily 
 made in large blocks (any sized basin can be made in 
 one piece), there is no jointing required, as is the case 
 with terra cotta, which is another form of artificial 
 stone. Fountains composed of fine concrete are made 
 in a similar way to that described for making and cast- 
 ing vases. 
 
 Concrete Tanks, — Concrete tanks to contain water, 
 and for a variety of manufacturing purposes, are now 
 largely in use. They are strong and durable, and hav- 
 ing hard smooth surfaces, they are easily washed and 
 kept clean. Being impervious to vermin, damp, and 
 atmospheric influences, they are the coolest and most 
 sanitary water cisterns that can be used. Cattle troughs 
 are best made in concrete. Concrete tanks have been 
 used as water and silicate baths for indurating con- 
 crete casts, and during their constant use for over a 
 decade no signs of cracks or damp are visible. They 
 were made in one piece, varying in size from 6 feet up 
 to 18 feet long, 3 feet to 7 feet wide, 2 feet 6 inches to 
 
HOW TO USE THEM 
 
 447 
 
 4 feet high^ and from 3 to 4^2 inches thick. Some were 
 castj but the large ones were made in situ. The method 
 of construction (for in situ work) being simple and ex- 
 peditious, the total cost is small. For a tank 9 feet long, 
 4 feet 6 inches wide, 2 feet 6 inches high, and 3^/2 inches 
 thick, first frame up wood sides and ends to the above 
 length, width, and height, then make inside boards, 
 the lengths and widths being the same as above, less 
 the tank thickness, and the heights less the bottom 
 thickness. The sides and ends are hung by means of 
 cross battens laid on the upper edges of the outside 
 framing, and kept in position with inside stays. This 
 leaves an open and continuous space at the sides, ends, 
 and bottom. The constructive materials are 1 part of 
 Portland cement and 2 of fine slag or granite, gauged 
 stiff, and laid over the bottom. Next, the open sides 
 and ends are filled up, taking great care that the whole 
 mass is thoroughly consolidated by ramming. The 
 stuff for the sides and ends should be laid in layers 
 from 6 to 8 inches deep, each layer being well rammed 
 before the next is laid. 
 
 The angles are strengthened by inserting angle irons 
 during the process of filling in. As soon as the concrete 
 is set the inner boards are removed, and if the surface 
 is smooth or dry, it must be keyed with a coarse drag 
 or a sharp hand pick. It is then swept and wetted to 
 cleanse it and stop the suction, so as to ensure perfect 
 cohesion, and allow the final coat to retain its moisture 
 during the process of trowelling and the stuff setting. 
 
 The finishing coat is composed of neat cement, the 
 finer ground the better, as percolation through con- 
 crete made with a finely ground cement is less liable 
 than when made with a coarsely ground cement. 
 
448 CEMENTS AND CONCRETES 
 
 The final coat is laid about 3/16 inch thick^ and pre- 
 ceded by brushing the surface with liquid cement to 
 fill up all crevices, and afford better adhesion between 
 the surface and the final coat. When the stuff is firm, 
 it is well trowelled to a fine and close surface. The 
 outer boards are then removed, and the surface finished 
 in a similar way. 
 
 Concrete Sinks. — Concrete sinks can be made to any 
 desired size or form. They are cast in wood or plaster 
 moulds, and are composed of 1 part of Portland cement 
 to 2 parts of fine crushed granite or other hard aggre- 
 gate. They are made with rebated holes for traps. The 
 ordinary size are as follows : 2 feet 6 inches by 1 foot 
 8 inches ; 2 feet 9 inches by 1 foot 8 inches ; and 3 feet 
 by 2 feet, all 6 inches deep, and from 2 to 3 inches thick. 
 
 Garden Edging. — Plain and ornamented edgings are 
 now made in concrete. They are made in various 
 lengths. The most useful size is 3 feet long, 6 inches 
 deep^ and 2 inches thick. They can be made to any 
 curve, and tinted to any shade. 
 
 Concrete Vases. — During the last half-century thou- 
 sands of vases, composed of fine concrete — commonly 
 called artificial stone'' — have been used for the dec- 
 oration of buildings and practical use in gardens, con- 
 servatories, &c. For vases that are cast in sections the 
 thickness of large and open parts, such as the ^'body, " 
 are regulated by means of a plaster core, which is 
 placed in the open mould. The contour of the core 
 must be so arranged that the cast will draw from the 
 core, or vice versa. For some forms of vases, the core 
 must be made in pieces similar to a piece mould. The 
 method of making, moulding, and casting — the latter 
 by the aid of a template instead of a cores 
 
HOW TO USE THEM 
 
 449 
 
 Concrete Mantel Pieces. — Chimney-pieces of all sizes 
 and shapes are now extensively made in fine concrete. 
 They are generally made in wood moulds, plaster 
 moulds being let in the main mould for ornamental 
 parts. They are often made in colored concrete. 
 
 Colored Concrete. — Concrete casts, also work laid in 
 situ, can be colored to imitate any natural stone. This 
 is effected by mixing mineral oxides of the required 
 color with the cement used for the surface coat. The 
 color coat should not exceed % inch in thickness, as 
 oxides are too expensive to use for the entire thickness 
 of the cast. The quantity of oxide to be added to the 
 cement depends upon the strength of the oxide. Some 
 are much stronger than others. Five per cent, of a 
 strong oxide will impart a close resemblance of the 
 desired color to the concrete, but a weak oxide will re-° 
 quire from 10 to 15 per cent., and even 20 per cent., to 
 obtain the same color. Some of the red oxides range 
 in color from scarlet or Turkey red, gradually deepen- 
 ing to chocolate. Some oxides contain 95 per cent, of 
 pure ferric oxide, w^hich is made from copperas, or, 
 scientifically speaking, sulphate of iron. This is a by- 
 product, and is frequently evolved from waste acid 
 liquors at tinplate works, and is obtained in large quan- 
 tities from South Wales. This kind of oxide is far 
 more suitable for coloring concrete than ochres and 
 most of the earthy oxides. Earthy colors, like Venetian 
 red and umber, soon fade and have a sickly appearance. 
 The oxides should be intimately mixed with the cement 
 in a dry state before it is gauged. The mixing is gen- 
 erally done by hand, but better results are obtained by 
 the use of grinding machine. It is a safe plan to try 
 various proportions of color and cement and gauge 
 
450 CEMENTS AND CONCRETES 
 
 small parts, and when set and dry select those most 
 suitable for the desired purpose. All cast work, as soon 
 as extracted from the moulds, should be examined, and 
 any blubs stopped and chipped parts or other minor 
 defects made good while the work is moist or green, 
 using neat cement and colors in the same proportion 
 as used for the surface stuff. Colored surfaces may be 
 greatly improved by brushing the cast as soon as set 
 with a solution of the same color as used for the sur- 
 face coat. A color solution, made by mixing the color 
 with water and a solution of alum, is very useful for 
 coloring Portland cement, with or without sand. If this 
 coloring solution is brushed over the surface while it 
 is moist or semi-dry, a good standing color can be ob- 
 tained without mixing color with dry cement. This 
 method will be found useful for sgraffitto, &c. 
 
 A novel and color-saving method, for coloring the 
 upper surfaces of slabs or other flat casts, is effected 
 by first filling in the mould in the usual way, then 
 placing the colored cement in a dry state in a hand 
 sieve, and then violently shaking or tapping the sides 
 of the sieve^ so as to sprinkle the colored cement uni- 
 formly over the surface until it is nearly 1/16 inch 
 thick. The surface is then trowelled in the usual way. 
 The sprinkling must be done as soon as the main body 
 of the stuff is ruled off, so as to obtain a homogeneous 
 body. Another and a novel method which may be ad- 
 vantageously employed for finishing slab or other large 
 surfaces in a mould is as follows : A fine finished face 
 is more readily obtained by using a smoothing knife 
 (for brevity termed a shaver") than by a trowel. A 
 shaver is a piece of polished steel about 3 inches wide 
 and % inch thick, the length being regulated according 
 
HOW TO USE THEM * 451 
 
 to the width of the mould, and allowing about 8 inches 
 at each end for handles. For instance, for a slab 2 feet 
 wide, the shaver should be 3 feet long. This allows 2 
 feet for the surface of the cast, 3 inches to bear on the 
 rims of the mould, each 1 V> inches wide ; 8 inches for 
 the handles, each 4 inches long; and 1 inch for play. 
 One edge or side is cut to an angle of 45°, so as to 
 form a cutting edge. The method of filling in, coloring, 
 and finishing the surface of the slab is as follows : First 
 fill in the mould with the concrete, ramming and beat- 
 ing it as already described until the stuff is about 1/16 
 inch above the mould rims, then clean off the stuff on 
 the rims with a wood template (rebated to fit the width 
 of the rims), and lay the shaver flat on the rims, keep- 
 ing the cutting edge outwards, and then push it for- 
 ward, keeping it flat on the rims, so as to shave off the 
 superfluous stufit". This done, sprinkle the colored ce- 
 ment, Avith the aid of a sieve, until about 1/16 inch 
 thick; then clean the rims again, and pass the shaver 
 forwards and backwards twice or thrice, which will 
 leave a straight, smooth, and uniform-colored surface. 
 This method effects a considerable saving in the amount 
 of oxide and of time. The thickness of the coloring 
 stratum is reduced mechanically to the minimum (about 
 1/32 inch), which is all sufficient for coloring purposes 
 where the surface is not subjected to frictional wear. 
 
 As already mentioned, bullocks' blood mixed with 
 cement gives a near resemblance to red brick, but it is 
 not a desirable material to work with, and the same 
 effect can be obtained by the use of red oxides. Red 
 sand, brick, and stone, all finely ground, have been em- 
 ployed for coloring cement surfaces^ but if too fine or 
 in large quantities they weaken the surface; and if 
 
452 CEMENTS AND CONCRETES 
 
 coarse-grained they possess little coloring effect, be- 
 cause the particles are liable to show singly, causing a 
 spotty appearance, or the cement entirely covers the 
 surface of each particle of sand. Powdered glass, mar- 
 ble, flint, alabaster, metal filings, and mineral coloring 
 can be effectively employed for coloring concrete sur- 
 faces by mixing with the cement used for the surface 
 coat. The surface is improved by rubbing and stoning, 
 also polishing, after the work is dry. ,Other methods 
 and quantities of colors for coloring Portland cement 
 surfaces are given. 
 
 Fixing Blocks. — Concrete fixing blocks do not shrink, 
 warp, or rot. Consequently they are superior to wood 
 fillets, &c. They are principally used in concrete floors, 
 stair landings, and walls, as bearings and fixing points 
 for wire-lathing and fibrous plaster work. Floor boards 
 may also be fixed to them. They are also built into 
 brick walls for similar purposes, as well as for external 
 wall tilings. For ceilings, stair soffits, and landings, 
 the blocks are laid on the centrings where required, 
 and permanently secured by laying concrete between 
 and over them. For bearings and fixing flooring boards, 
 they are secured flush". 
 
 TYPICAL SYSTEMS OF REINFORCED CONCRETE 
 CONSTRUCTIONS FROM VARIOUS SOURCES. 
 
 Of the interesting features of modern civil engineer- 
 ing, interesting because of their extreme novelty and 
 successful application, reinforced concrete is probably 
 most noteworthy because of its unique adaptability. 
 How striking is the influence of steel reinforcement is 
 best exemplified by a reference to Fig. 1. There tw j 
 
HOW TO USE THEM 
 
 453 
 
 beams are shown designed to carry ordinary floor loads, 
 the one made entirely of concrete and the other of con- 
 crete with a sheet of expanded metal imbedded in the 
 tensile portion of the beam. The saving in mere weight 
 of concrete alone is apparent ; and when we remember 
 that the adoption of floor beams entirely of concrete 
 means an increase of thickness of nine inches or as- 
 suming flve to eight floors, an increase in the total 
 height of the building (with extra cost and heavier 
 walls, together with heavier foundations to carry them) 
 of from four to six feet, we see that even as regards 
 initial outlay for materials, the introduction of settle 
 reinforcement into concrete construction is of import- 
 ance. 
 
 So far as economy in initial cost of materials is con- 
 cerned, reinforced concrete is undoubtedly cheaper 
 than either concrete or steel alone. It is not very easy 
 to demonstrate this economy except by comparative 
 cost in individual cases, but an approach to a systematic 
 comparison has been made by Mr. Walter Loring Webb, 
 as follows : A cubic foot of steel weighs 490 pounds. 
 Assume as an average price that it can be bought and 
 placed for 4.5 cents per pound. The steel will therefore 
 cost $22.05 per cubic foot. On the basis that concrete 
 may be placed for $6 per cubic yard, the concrete will 
 cost 22 cents per cubic foot which is 1 per cent of the 
 cost of the steel. Therefore, on this basis if it is neces- 
 sary to use as reinforcement an amount of steel whose 
 volume is in excess of 1 per cent of the additional con- 
 crete which would do the same work, there is no econ- 
 omy in the reinforcement, even though the reinforce- 
 ment is justified on account of the other considerations. 
 Assuming 500 pounds per square inch as the working 
 
454 CEMENTS AND CONCRETES 
 
 compressive strength of concrete^ and 16,000 as the per- 
 missible stress in steel, it requires 3.125 per cent of steel 
 to furnish the same compressive stress as concrete. On 
 the above basis of cost, the compression is evidently 
 obtained much more cheaply in concrete than in steel 
 — in fact, at less than one-third of the cost. On the 
 other hand^ even if we allow 50 pounds per square inch 
 tension in the concrete and 16,000 pounds in the steel, 
 it requires only 0.21 per cent of steel to furnish the 
 
 i w 
 
 Pig. l.-;^These Beams Are Designed to Carry the Same 
 Load. The Upper is of Reinforced Concrete, the 
 Lower of Plain Concrete. 
 
 same strength as the concrete, which shows that, no 
 matter what may be the variation in the comparative 
 price, of concrete and steel, steel always furnishes ten- 
 sion at a far cheaper price than concrete, on the above 
 basis at less than one-third of the cost. The practical 
 meaning of this is^ on the one hand, that a beam com- 
 posed wholly of concrete is usually inadvisable, since its 
 low tensile strength makes it uneconomical, if not actu- 
 ally impracticable, for it may be readily shown that, 
 beyond a comparatively short span, a concrete beam 
 will not support its own weight. On the other hand^ 
 
HOW TO USE THEM 455 
 
 on account of the cheaper compressive stress furnished 
 by concrete, an all-steel beam is not so economical as 
 
 Fiff. 2— Types of Steel Reinforcin«: Rods, 
 
 a beam in which the concrete furnishes the compres- 
 sive stress and the steel furnishes the tensile stress. 
 
 Fig. 3.— A Reinforced Concrete Pier for Railway 
 Traffic' 
 
 This statement has been very frequently verified when 
 comparing the cost of the construction of floors de- 
 
456 CEMENTS AND CONCRETES 
 
 signed by using steel I-beams supporting a fire-proof 
 concrete floor, and that of a concrete floor having a 
 similar floor slab but making the beams as T-beams of 
 reinforced concrete. 
 
 A good idea of reinforced concrete construction can 
 be obtained from Fig. 3, which is an isometrical pro- 
 jection of a portion of a pier strong enough to carry 
 the heaviest railway traffic. The disposition of the 
 steel work is shown in the piles, the main girders, and 
 beams; and the manner in which the steel rods run- 
 ning along the tensile or bottom side of the girders 
 and beams are bent up over the top of the pile, which 
 is here the tensile member (the beams being continu- 
 ous), and then down again to the bottom of the girders 
 and beams, is most instructive. 
 
 Fi^. 4.— Method of Joining Columns and Floors. 
 
 The sections of the steel employed vary in different 
 systems, being round, flat, square, angle, and tee — Fig. 
 2. In all cases the simplest section is the best, as it 
 costs less, and readily allows the concrete to be rammed 
 into the closest contact with the entire surface of the 
 armoring. In America the Eansome system is most 
 extensively used — a system in which a bar of twisted 
 
HOW TO USE THEM 
 
 457 
 
 steel is employed. Small sections are better than large 
 ones, for by their use we obtain a more uniform dis- 
 tribution of stress in the steel; we can also readily 
 bend and work them into any required shape; and 
 finally the most economical disposition of material is 
 obtained, the metal being placed at the maximum dis- 
 tance from the neutral axis. 
 
 Expanded metal meshing (Fig. 6) is increasingly em- 
 ployed, more particularly m the lighter forms of con- 
 struction. It consists of sheets of metal which have 
 been mechanically slit and expanded, so as to produce 
 a network. This type of reinforcement has many and 
 obvious advantages. Its mere existence is proof of good 
 steel, and it forms an excellent key for concrete too 
 thin to permit reinforcement in the form of rods ; thus 
 it is very useful for concrete plaster, ceiling, and parti- 
 tion wall work. A good example of reinforced con- 
 crete in which expanded metal is used may be found 
 in the Monier system (Fig. 5). An improvement on 
 
 Fig. 5.— The Monier System, 
 
458 CEMENTS AND CONCRETES 
 
 this system is the Clinton method (Fig. 11) of using 
 an electrically welded wire netting in combination with 
 concrete. Clinton fabric consists of drawn wire of 6 
 to 10 gauge, which may be made in lengths up to 300 
 feet. The system is therefore a continuous bond system, 
 which prevents the entire collapse of a span unless the 
 weight imposed is sufficient to break all the wires. 
 
 Fi^4 07— Expanded Metal. 
 
 - Columns and Piles. — Reinforced columns are made 
 with either square, rectangular, or circular sections. 
 They are reinforced with from four to twenty rods, the 
 diameters of which vary from % to 2^/2 inches. The 
 rods are placed as nearly as practicable to the circum- 
 ference of the column, so as to give the greatest radius 
 of gyration for the section ; but they are never placed 
 so near the surface that they have not at least one or 
 two inches protective covering. The steel so disposed 
 is able to take up the tensile stresses which may be 
 
HOW TO USE THEM 
 
 459 
 
 induced in the column by eccentric loading, lateral 
 shocks wind pressure, and the pull of belting. 
 
 Columns and piles are made in wooden boxes, each 
 consisting of three permanent sides and a fourth side 
 which is temporary and removable. Under the patent 
 rights of Francois Hennebique the reinforcing is placed 
 
 Ifig. 7. -£aiisome iSysslem of Erecting Colamns* 
 
 in these boxes, and adjusted by gauges to within one or 
 two inches of the sides. The concrete is laid and 
 rammed, about six inches at a time, with small hand 
 rammers. The open side of the box is built up by 
 battens fitting into grooves in the permanent sides, as 
 the work proceeds ; this enables inspection of the work 
 
460 CEMENTS AND CONCRETES 
 
 to be made, and facilitates the placing of the ties at the 
 proper positions. The ties are made of round wire 3/16 
 
 Fig. 8»— Wood Centering and Ransome Steel Bars for 50-t*oot 
 Floor Span* 
 
 inch diameter and are dropped down over the top of 
 the steel rods. They are spaced down two-inch centres 
 
HOW TO USE THEM 
 
 461 
 
 at the bottom and top, to twelve-inch centres in the 
 centre of length of the column, and are intended to 
 prevent the steel rods from spreading out under the, 
 action of longitudinal loads. Fig. 4 shows the method 
 of joining columns to the floor. 
 
 Fig. 9#— Concrete Power Plant in Course of 
 Construction, 
 
 In the Ransome columns as exemplified in a recently 
 constructed factory building (Fig. 7), the vertical re- 
 inforcement consists of round rods with the connections 
 made about 12 inches above the floor line ; in order that 
 
462 CEMENTS AND CONCRETES 
 
 these rods might be continuous the ends were threaded 
 and connected with sleeve nuts, thereby developing the 
 full strength of the rods. Horizontal reinforcement 
 was also u.sed, consisting of hoops formed by a spiral 
 
 4^ 
 
 Fig, 10.— Slabs of Concrete Ready for Roof. 
 
 made from ^4 inch diameter soft wire, having a pitch 
 or spacing of 4 inches in the basement columns, and 
 gradually increasing to a pitch of 6 inches in the top 
 story (Fig. 12). 
 
 According to Mr. Henry Longcope the first innova- 
 tion in concrete piles was the sand pile, produced by 
 
HOW TO USE THEM 463 
 
 driving a wooden form in the 
 ground and withdrawing it, 
 the hole being filled with 
 moist sand well rammed. The 
 next method adopted was to 
 drive a metal form into the 
 ground and after withdrawal 
 to fill the hole with concrete. 
 This was not successful, as it 
 was open to the serious objec- 
 tion that on withdrawing the 
 form, the ground would col- 
 lapse before the concrete could 
 be inserted. Still another 
 method was introduced, which 
 consisted in dropping a cone- 
 shaped five ton weight a num- 
 ber of times from a consider- 
 able height, in order to form 
 a hole, which was afterward 
 filled with concrete. This 
 method never passed the ex- 
 perimental stage. Coming to 
 more successful systems we 
 may mention a method of 
 moulding a pile of concrete, 
 allowing it to stand, and then 
 driving it into the ground, a 
 cap being used to protect the 
 head. 
 
 Of modern systems which 
 have proven successful, Gil- 
 breth's pile must first be re- 
 
CEMENTS AND CONCRETES 
 
HOW TO USE THEM 465 
 
 corded. Gilbreth used a molded corrugated taper pile, 
 cast with core hole the entire length of the pile, which is 
 jetted down by a water jet and finally settled by hammer 
 blows. 
 
 Features which recommended the Gilbreth piles are 
 the opportunities for complete inspection before driv- 
 ing and the fact that they save time because they can 
 be cased while excavation is going on. After being 
 driven they can be loaded immediately. Naturally they 
 present considerable skin friction. The making of these 
 piles above the ground surface also does away with the 
 possibility of their being damaged or squeezed out of 
 shape by the jar occasioned by driving forms for ad- 
 joining piles. 
 
 Still another method is used by Raymond. Under 
 this . system piles are usually put in by either of two 
 methods, the jetting method or the pile core method. 
 The water jet system is used only where the material 
 penetrated is sand, quicksand, or soft material that will 
 dissolve and flow up inside the pile when the water is 
 forced through the pipe, thus causing the shell to settle 
 until it comes in contact with the next shell, and so on 
 until the desired depth has been reached. The shells 
 are filled with concrete simultaneously with the sinking 
 process, and when necessary spreads are attached to 
 keep the hole in perfect line with the pipe. The % 
 inch pipe is left in the centre of the pile and gives it 
 greatly increased lateral strength. If desired, the 
 lateral strength may be further increased by inserting 
 rods near the outer surface of the concrete. By this 
 method, piles of any size up to two feet in diameter at 
 the bottom and four feet at the top can be put through 
 
466 CEMENTS AND CONCRETES 
 
 any depth of water and to a suitable penetration in 
 sand or silt (water sediment). 
 
 The pile-core method is the one most generally used 
 for foundation work and consists of a collapsible steel 
 pile core, conical in shape, which is incased in a thin, 
 tight-fitting metal shell. The core and shell are driven 
 into the ground by means of a pile driver. The core 
 . is so constructed that when the desired depth has been 
 reached it is collapsed and loses contact with the shell, 
 so that it is easily withdrawn, leaving the shell or. cas- 
 ing in the ground, to act as a mold or form for the 
 concrete. When the form is withdrawn, the shell or 
 casing is filled with carefully mixed Portland cement 
 concrete, which is thoroughly tamped during the filling 
 process. 
 
 The simplex system uses another method in which 
 the driving form consists of a strong steel tube, the 
 lower end of which is fitted with powerful tooth jaws, 
 which close together tightly, with a point capable of 
 opening automatically to the full diameter of the tube 
 while being withdrawn. The point of the form closely 
 resembles the jaws of an alligator. At the same time 
 the form is being withdrawn, the concrete is deposited. 
 
 It is so evident that concrete is vastly superior to 
 wood in the construction of piles that it is almost su- 
 perfluous to mention the points of superiority. Con- 
 crete is not subject to rot or the ravages of the teredo 
 worm, neither can the piles constructed of concrete be 
 destroyed by fire, and no cost is attached for repairs. 
 While it is not possible to give accurate statistics as to 
 the life of a wooden pile, as it varies so much under 
 different conditions, yet we know that in some cases 
 a wooden pile is rendered worthless in a very few years. 
 
HOW TO USE THEM 
 
 467 
 
 especially when the surrounding material is composed 
 of rotted vegetation^ or where the pile is exposed by 
 the rise and fall of tides. It is also impossible to state 
 the exact cost of a concrete pile, as it varies also ac- 
 cording to conditions. Ordinarily speaking, a concrete 
 pile will cost from one and one-half times or two times 
 as much as a wooden pile ; but in order to illustrate 
 where a saving can be made, the following extract is 
 given from a report on the piles driven at the United 
 States Naval Academy at Annapolis, Md. : 
 
 '^The original plans called for 3,200 wooden piles 
 cut off below low water with a capping of concrete. 
 To get down to the low water level required sheet pil- 
 ing, shorting and pumping, and the excavating of near- 
 ly 5,000 cubic yards of earth. By substituting concrete 
 piles, the work was reduced to driving 850 concrete 
 piles, excavating 1,000 cubic yards of earth and placing 
 of 1,000 cubic yards of concrete." 
 
 In the work mentioned, the first estimate for wooden 
 piles placed the cost at $9.50 each, while the estimate 
 for concrete piles was placed at $20 each, yet the esti- 
 mate based on the use of wood piles aggregated $52,840, 
 while the estimate based on the use of concrete piles 
 w^as $25,403, or a total saving in favor of concrete of 
 over $27,000. 
 
 In several instances piles have been uncovered to 
 their full depth, and they were found to be perfectly 
 sound in every particular. By surrounding the opera- 
 tion with the safeguards provided, it is almost impos- 
 sible to make a faulty pile. The concrete is made as 
 wet as good practice will allow. Constant ramming and 
 dropping the concrete from a considerable height tend 
 to the assurance of a solid mass, then the target on 
 
468 CEMENTS AND CONCRETES 
 
 the ramming line or the introduction of an electric light 
 into the form shows what is being done at .the bottom 
 of the form. 
 
 Floors, Slabs and Roofs, — The system of construction 
 for floors, slabs, and roofs is determined by the extent 
 of the work and the nature of the loads to be carried. 
 If intended for small buildings and offices, the items 
 can be made before erection (Figs. 9 and 10) ; but in 
 the case of warehouses^ factories, piers, and jetties, 
 where live loads and vibrator stresses have to be borne, 
 a monolithic structure is secured by building in molds 
 directly on the site. For the lighter classes of mono- 
 lithic structure, expanded metal is admirably suitable; 
 it is also much used for the roofs of reservoirs, and for 
 thin partitioned walls. The meshing is simply laid 
 over the ribs or floor beams, which have been already 
 erected, and the green concrete is applied to the acquired 
 thickness, being supported from below by suitable sup- 
 porting work, which is removed as soon as the concrete 
 has set. In cold storage factories, the floor beams and 
 ceilings are invariably erected first, the floor being laid 
 afterward. The ceiling is then solid with the floor 
 beams on their under side, and the floor is solid with 
 them on their upper side, the air space between being a 
 great aid to the maintenance of a low temperature for 
 refrigeration. 
 
 In the Monier floors the reinforcement consists of 
 round rods varying from inch to % inch diameter. 
 The rods are spaced at about six times their diameter, 
 and are crossed at right angles, being connected by 
 iron wire bound round them. This artificial method of 
 securing the rods takes considerable time, and is thus • 
 a somewhat costly process. To produce continuity of 
 
HOW TO USE THEM 
 
 469 
 
 metal, the different lengths of rods are overlapped for 
 about 8 to 16 inches^ and bound with wire. 
 
 The Schluter are similar to the Monier floors, but 
 the rods are crossed diagonally, and the longitudinal 
 rods are of the same size as the transverse ones. The 
 Cottancin floors have their rods interlaced like the 
 canes of a chair seat or a basket, and the Hyatt floors 
 have square rods with holes through which small trans- 
 verse rods pass. Over fifty systems of reinforcing are 
 in use, and in most cases the only points of difference 
 are the shape of the section and the method of attach- 
 ment and adjustment. 
 
 Beams. — It is obvious that, as the span increases, a 
 limit will soon be reached beyond which it is not eco- 
 nomical to use plain floor slabs, far their dead weight 
 becomes of such magnitude as to prohibit their use. We 
 have thus to resort to a division of the main span by 
 cross beams resting on columns, and the floor is laid 
 on these beams, which are arranged to take as much of 
 the load as to render it possible to reduce the thick- 
 ness of the floor within reasonable limits. Reinforced 
 concrete beams are typical of the construction in which 
 the merits of two component materials are made to 
 serve a common end ; but in the particular case of steel 
 and concrete, the actual part played by the steel is 
 not at all well understood. 
 
 Speaking generally, beams do not differ in construe- 
 tional details from floors. The same reinforcement is 
 used in both, the only difference being, that as beams 
 are usually deeper than floors, the shearing stresses be- 
 come more pronounced, the greater provision has to be 
 made for them by a liberal use of stirrups or vertical 
 binding rods. In some systems the reinforcement con- 
 
470 CEMENTS AND CONCRETES 
 
 sists entirely of straight rods, disposed in any part of 
 the beam where tensile stresses are likely to be called 
 into play. In others, specially bent rods are joined or 
 welded to straight rods, disposed and when welding has 
 to be done it would appear that wrought iron is more 
 suitable than steel. 
 
 It is usual to arrange the dimensions of the beams 
 so that the whole of the compressive stresses are taken 
 by that portion of the concrete on one side of the neu- 
 tral axis; but in some cases, as with continuous beams 
 or heavy beams of small depth, a portion of the rein- 
 forcement is disturbed along compressed portion of the 
 beam, the steel rods either taking up the excess of 
 compressive stress over that at which the i3oncrete can 
 be safely worked, or else taking up the tensile stresses 
 at the places where they occur over the supports. As 
 a general rule we may take it that the economical depth 
 for a reinforced concrete beam^ freely supported at 
 both ends, is one-twentieth the span, and is thus ap- 
 proximately the same as that of a steel girder of equal 
 strength. Reinforced concrete beams are now made for 
 spans up to 100 feet for buildings, and 150 feet for 
 bridges. But for each class of work beyond this limit, 
 the weight becomes excessive. Several arched ribs, 
 for much greater spans have^ however, been success- 
 fully built. 
 
 The beams are made in much the same way as piles 
 and columns; they can be made in sheds on the site, 
 or in the actual position they are to occupy when fin- 
 ished. The ceiling and beams are erected first, the 
 floor being afterward worked on the top of the beams. 
 We thus obtain a very perfect monolithic structure in 
 which any vibration set up by machinery, falling loads, 
 
HOW TO USE THEM 
 
 471 
 
 etc., will be of much less extent than with any ordinary 
 type of building, in which there is often a great want 
 of rigidity, the beams and arches being loose and able 
 to vibrate independently of other parts of the struc«= 
 ture. 
 
 Concrete being as weak in shear as in tension, pro- 
 vision is also required to take the shearing stresses. 
 Some American designers have to this end patented 
 special forms of reinforcement bar, in which each main 
 tension bar has projecting upward from it ties inclined 
 at the angle of 45 deg. (Kahn system.) These ex- 
 tend to the top of the bar and take the tensile stresses 
 arising from the shear. The corresponding compres- 
 sive stress at right angles to this is carried by the con- 
 crete. The system is efficient and on large spans, where 
 weight must be reduced to a minimum, it has its ad- 
 vantages. 
 
 Thus, in the Ransome system (Fig. 12), the shearing 
 stresses at the end of a beam are taken up by inclined 
 reinforcing rods imbedded in the concrete at the junc- 
 tion of beam with column. 
 
 Arches. — Concrete has long had an extensive ap- 
 plication in the building of arches, but until the in- 
 troduction of reinforced concrete the arches that could 
 be economically and safely constructed were limited to 
 spans of a few feet. The general rule that the line of 
 resistance fell within the middle third had to be ob- 
 served for simple concrete arches, as for those in brick- 
 work and masonry; and the thickness of the arches 
 at the crown was thus approximately the same whether 
 built in either of these materials. The introduction of 
 steel reinforcement, however, made it possible not only 
 to reduce the thickness of the ring of a given load- 
 
HOW TO USE THEM 
 
 carrying capacity, but by suitably providing for tne 
 tensile stresses to enable arches of much greater span 
 and smaller rise to be built. Some general types of 
 arches in reinforced concrete are shown in Figs. 13, 14, 
 15 and 16. Fig. 13 'shows an ordinary arch with top 
 and bottom armature. In many cases where the ten- 
 sile stresses can safely be carried by the concrete the 
 top armature can be omitted. In the Melane arches, 
 shown in Fig. 14, the top and bottom armatures are 
 connected by ligatures, and in the Hennebique arches 
 (Fig. 15) stirrups are used. As a general rule, hinges 
 should be built at the stringings and the crown, for the 
 calculations are much simplified, and the line of re- 
 sistance goes through the hinges; the arches also ad- 
 just themselves better to the load and to any slow 
 temperature changes, and when the centering is struck 
 the arch can better take its bearings without cracking. 
 The methods of calculations for arches are as numer- 
 ous as those for beams, and generally speaking are as 
 irrational. The Monier system is the one most gen- 
 erally adopted, and over 400 bridges built on this sys- 
 tem now exist in Europe. In America expanded metal 
 and Clinton electrically-welded fabric are often used. 
 An example of the latter construction will be found in 
 Fig. 17. 
 
 SOME MISCELLANEOUS ITEMS. 
 
 Lintels. — Concrete lintels and beams are fast super- 
 seding those made of stone and wood. Lintels are 
 generally cast and then fixed. 
 
CEMENTS AND CQNCIiETES 
 
HOW TO USE THEM 
 
 475 
 
 Concrete Walls. — Many ingenious plans have been 
 introduced as substitutes for wood framing for retain- 
 ing concrete while constructing walls and partitions. 
 The most simple method is as follows : Cast a number 
 of concrete angle slabs with an L section, and then 
 place them level in contrary directions, thus [ 
 spaced to the width of the proposed partition or wall 
 until the desired length of wall is completed, and fill 
 the openings with rough concrete. When set, place 
 another row on this (taking care to break the joints by 
 overlapping), and so on, until the desired height is 
 obtained. Concrete for walls formed in situ should be 
 deposited in layers, taking care that each layer is thor- 
 oughly rammed and keyed, as described under the 
 heading of ^ ^Ramming." A suitable finish for ordi- 
 nary purposes, for rough walls built in situ, may be 
 obtained by rough trowelling." This is done by 
 first gauging 1 part of Portland cement, 1 part of old 
 lime putty, and 2 parts of sand. The adding of lime 
 renders the stuff more plastic and easy to work, with- 
 out decreasing the impermeability of the work. This 
 
 limed cement'' is applied with a hand-float, and is 
 thoroughly worked into the crevices of the concrete, 
 but leaving no body on the surface. The surface is 
 then finished by brushing with a wet stock-brush. The 
 walls should be well whetted before the stuff is applied. 
 
 Strong Rooms. — Concrete is frequently employed in 
 the construction of strong-rooms that are situated 
 underground, and are rendered damp-proof as well as 
 burglar-proof, which is useful for the storage of docu- 
 ments. 
 
 Concrete Coffins and Cementation. — The great im- 
 provements in the manufacture of Portland cement 
 
476 CEMENTS AND CONCRETES 
 
 during the last decade has so cheapened and improved 
 the quality as to bring it more and more to the front 
 as one of the most useful and important materials for 
 a variety of purposes. One of the latest uses found for 
 it is in the construction of coffins, by the author, whose 
 invented and registered idea was that such a coffin, 
 made of specially prepared metallic concrete, would 
 be impermeable^ and practically indestructible, and 
 that it would obviate the danger of spreading the 
 poisons of disease by preventing the escape of noxious 
 gases. The lid having a strong piece of plate glass 
 embedded in the concrete, and directly over the face, 
 enabled the mourners to see the features of the depart- 
 ed. The edge of the open coffin had a sunk groove, 
 and the lid a corresponding projection, only smaller, 
 to allow for a coat of fine cement. When the joints 
 were bedded and pressed together until the excess ce- 
 ment oozed out, the coffin was hermetically sealed. 
 The coffin should be left uncovered by cement for 
 identification, and so that friends could view it until 
 the time of removal to the cemetery. The face could 
 then be covered with quick-setting cement, which, join- 
 ing with the other portion of cement, would perma- 
 nently embalm the body, which would further be pro- 
 tected by fixing the lid in a similar way. If the prop- 
 erties of this class of coffin are taken into considera- 
 tion, the expense will be comparatively less than that of 
 wood. If expense is not a special consideration, the 
 coffin can be enriched with armorial bearings or other 
 devices. The concrete may also be polished like real 
 granite. One objection was raised as to the weight, 
 but the old stone coffms and those of oak lined, with 
 lead were also heavy. Besides, the weight would be 
 
HOW TO USE THEM 
 
 477 
 
 a protection against body-snatchers, and bearing in 
 mind that a coffin is only moved about once in a life- 
 time, or rather at death, the question of weight is un- 
 important. Cementation, from a sanitary point of 
 view, would be equal if not superior to cremation. In 
 case of an epidemic, the coffins could be cemented at 
 once, and stacked in the cemetery until graves or vaults 
 were prepared for them. It may be safely said that it 
 is a clean, safe, effectual, rapid and sanitary method 
 of disposing of the dead. If their manufacture should 
 not cause any great amount of extra employment for 
 plasterers, the latter can at least make their own cof- 
 fins, in frosty weather, when most works are stopped, 
 and they could use them as baths during their life- 
 time. 
 
 Stonette, — Stonette is a composition of Portland ce- 
 ment and fine aggregate, to imitate any kind of stone, 
 and so made that it can be carved the same as natural 
 stone. The Portland cement must be thoroughly air< 
 slaked, finely sifted, and gauged with the natural ag- 
 gregate in the proportion of 2 of cement to 7 of ag- 
 gregate. The aggregate is composed of finely crushed 
 natural stone, the same as that to be imitated. This 
 should be passed through a fine sieve. It is necessary, 
 when imitating some stones, to add a small portion of 
 oxide to counteract the color of the cement. If a very 
 white stone is being imitated, the addition of a small 
 proportion of whiting or French chalk or well-slaked 
 white limestone, is necessary to obtain the desired 
 color. The material should be gauged stiff, and then 
 well rammed into the mould. The carving is best done 
 while the cast blocks are green. 
 
 Tile Fixing. — Tile fixing is in some places a sepa- 
 
478 CEMENTS AND CONCRETES 
 
 rate branch of the building trade^ but it is generally 
 recruited from the ranks of plasterers, and in some 
 districts it is done by plasterers. As regards the pro- 
 cess of placing the tiles, it is best to work from the 
 centre of the space, and if the design be intricate, to 
 lay out a portion of the pavement according to the 
 plan, upon a smooth floor, fitting the tiles together 
 as they are to be laid. Lines being stretched over the 
 foundation at right angles, the fixing may proceed, 
 both the tiles and the foundation being previously 
 soaked in cold water, to prevent the too rapid dry- 
 ing of the cement, and to secure better adhesion. The 
 border should be left until the last. Its position and 
 that of the tiles are to be obtained from the drawing, 
 or by measuring the tiles when laid loosely upon the 
 floor. The cement for fixing should be mixed thin, in 
 small quantities, and without sand. It is best to float 
 the tiles to their places, so as to exclude air, and fill 
 the spaces between them and the foundation. For fix- 
 ing tiles in grate cheeks, sides and backs of fire-places, 
 etc., equal parts of sand, plaster and hair mortar may 
 be used. These materials are sometimes mixed with 
 hot glue to the consistency of mortar. The tiles should 
 be well soaked in warm water. Keen's or other white 
 cements are used as fixing materials for wall tiles, neat 
 Portland cement (very often killed) being generally 
 used for floor work. Tiles may be cut in the follow- 
 ing manner : Draw a line with a pencil or sharp point 
 where the break is desired, then placing the tile on a 
 form board, or embedding it in sand on a flagstone, 
 tap it moderately with a sharp chisel and a hammer 
 along the line, up and down, or scratch it with a file. 
 The tile may then be broken in the hand by a gentle 
 
HOW TO USE THEM 
 
 479 
 
 blow at the back. The edges, if required, may be 
 smoothed by grinding or by rubbing with sand and 
 water on a flat stone. Tiles may also be sawn to any 
 desired size. Cement should not be allowed to harden 
 upon the surface of the tile if it can be prevented, as 
 it is difficult to remove it after it has set. Stains or 
 dirt adhering to tiles may be removed by wetting with 
 diluted muriatic acid (''spirits of salts''), care being 
 taken that the acid is all wiped off, and, after wash- 
 ing, the superfluous moisture must be wiped off with 
 a clean, dry cloth. In order to obtain a sound and 
 straight foundation, which is imperative for good per- 
 manent tile fixing, the substratum, whether on walls or 
 floors, should be composed of Portland cement gauged 
 with strong sand or similar aggregate in proportion 
 of 1 of the former to 3 of the latter. The surface must 
 be ruled fair and left rough, so as to form a fair bed 
 and key for the fixing materials and tiles. 
 
 Setting Floor and Wall Tile. — As this work properly 
 belongs to the plasterer, where no regular tile setter is 
 available, I have thought it proper to publish the fol- 
 lowing instructions for doing this work^ which are 
 taken from a treatise prepared for the Tile Manufac- 
 turers of the United States. This treatise, in pamphlet 
 form, was intended for distribution among buyers and 
 workers in tiles^ and the directions and suggestions 
 laid down in it are of the best^ and quite suited to the 
 wants of the workingmen : 
 
 Foundations. — A good foundation is always neces- 
 sary, and should be both solid and perfectly level. Tile 
 should always be laid upon concrete foundation, pre- 
 pared from the best quality of Portland cement and 
 clean, sharp sand and gravel, or other hard material. 
 
480 
 
 CEMENTS AND CONCRETES 
 
 (Cinders sJiould never he used, as they have a tendency 
 to destroy the life of the cement and cause it to dis- 
 integrate.) A foundation, however, may also be formed 
 of brick or hollow tile embedded solidly in and covered 
 with cement mortar. Concrete should be allowed to 
 thoroughly harden before laying the floor, and should 
 be well soaked with water before laying the tile. 
 
 Lime mortar should never be mixed with concreting. 
 
 Concrete should consist of one part Portland cement, 
 two parts clean sharp sand, two parts clean gravel, 
 and thoroughly mixed with sufficient water to form a 
 hard, solid mass when well beaten down into a bed, 
 which should be from inches to 3 inches thick. If 
 the concrete bed can be made over three inches in 
 thickness, the concrete can then be made of one part 
 Louisville cement^ one part clean sharp sand, one part 
 clean gravel and thoroughly mixed with sufficient wa- 
 ter, as above described. 
 
 For Floors. — The surface of the concrete must be 
 level and finished to within one (1) inch of the fin- 
 ished floor line, when tile % inch thick is used, which 
 will leave a space of ^/^ inch for cement mortar, com- 
 posed of equal parts of the very best quality Portland 
 cement and clean sharp sand. The distance below 
 the surface of the finished floor line, however, should 
 be governed by the thickness of the tile. 
 
 For Wood Floors. — When tiles are to be laid on wood 
 flooring in new buildings the joists should be set ^ve 
 inches below the intended finished floor line and spaced 
 about 12 inclies apart and thoroughly bridged, so as to 
 make a stiff floor^ and covered with one-inch boards 
 not over six inches wide (boards three inches wide 
 preferred),, and thoroughly nailed, and the joints % 
 
HOW TO USE THEM 
 
 481 
 
 inch apart to allow for swelling. (See No. 31.) (A 
 layer of heavy tar paper on top of wood flooring will 
 protect the boards from the moisture of the concrete, 
 and will also prevent any moisture from dripping 
 through to a ceiling below.) 
 
 Pig-. 31. 
 
 In Old Buildings. — ^Cleats are nailed to joists five 
 inches below the intended finished floor line, and short 
 pieces of boards % inch apart fitted in between the 
 
 FLOOR LlMg 
 
 IFLOOR 
 
 Pig-. 32. 
 
 joists upon the cleats and well nailed, and the joists 
 thorough^ bridged. The corners on the upper edge 
 of the joists should be chamfered off to a sharp point 
 (see Fig. 32), as the flat surface of the joists will give 
 an uneven foundation. AVhen the strength of the 
 joists will permit, it is best to cut an inch or more off 
 
482 CEMENTS AND CONCEETES 
 
 the top. (Where joists are too weak, strengthen by 
 thoroughly nailing cleats six inches wide full length 
 of joists.) When the solid wood foundation is thus 
 pref)ared, concrete is placed upon it as above directed. 
 
 Where Steel Beams and hollow tile arches are used, 
 frequently very little space is left for preparing a 
 proper foundation for setting tile, as the rough coating 
 is usually put in by the hollow tile contractor to pro- 
 tect his work, but this covering should always conform 
 
 Fig. 33. 
 
 to the requirements for a solid tile foundation. Should 
 this not be the case, the tile contractor should remove 
 sufficient of the covering to allow him to put down a 
 foundation that will insure a satisfactory tile floor. 
 (Cinders, lime, mortar or inferior material must never 
 be used.) 
 
 The tops of iron beams should be from three to four 
 inches below che finished floor line, to prevent floors, 
 when finished, showing lines of the beams. 
 
 For Hearths. — The foundation for hearths should be 
 placed upon a brick arch, if possible, to ensure perfect 
 fire protection, and then covered with concrete in the 
 same manner as directed for tile floors. If placed 
 upon a sub-foundation of wood, the concreting should 
 be at least six inches thick. (See Figs. 34 and 35.) 
 
HOW TO USE THEM 
 
 483 
 
484 CEMENTS AND CONCRETES 
 
 For Wa/^^.— When tiles are to be laid on old brick 
 walls the plaster must be all removed and the mortar 
 raked out of the joints of the brick work to form a key 
 for the cement. On new brick walls the points should 
 not be pointed. When tiles are to be placed on stud- 
 ding, the studding- should be well braced by filling 
 in between the studding with brick set in mortar to the 
 height of tile work (see Fig. 36) ; or brick work may be 
 omitted and extra studding put in and thoroughly 
 
 bridged, so as to have as little spring as possible, and 
 this studding then covered with sheet metal lathing. 
 (See Fig. 37.) {Tile must never he placed on wood lath 
 or on old plaster,) The brick walls must be well wet 
 with water and then covered with a rough coating 
 of cement mortar, composed of one part Portland ce- 
 
HOW TO USE THEM 485 
 
 ment and two parts clean sharp sand. When tiles are 
 placed on metal lathing, hair should be mixed with the 
 cement mortar to make it adhere more closely to the 
 lath. The cement mortar should be % inch thick, or 
 sufficient to make an even and true surface to within 
 one (1) inch of the intended finished surface of the 
 tile, when tile inch thick is used, which will allow 
 
 a- space of % inch for the cement mortar, composed as 
 above for rough coating the walls. The face of the 
 cement foundation should be roughly scratched and 
 allowed to harden for at least one day before com- 
 mencing to lay the tile. - If any lime is mixed with the 
 cement mortar for setting the tiles^ it should never 
 exceed 10 per cent., and great care must be used to 
 have the' lime well slaked^ and made free from all 
 
486 
 
 CEMENTS AND CONCRETES 
 
 lumps by running through a coarse sieve, in order to 
 guard against heaving" or swelling," and thus 
 loosening or ^ lifting" the tiles. 
 
 Important, — The foundation for both floor and wall 
 tiling should be thoroughly brushed, to remove all dust 
 and small particles adhering to it, and then well wet 
 before putting on the cement mortar. To ensure a 
 perfect bond it is best to coat the foundation by brush- 
 ing over it pure cement mixed in water. 
 
 Cement. — The very best quality of Portland cement 
 should always be used for setting either floor or wall 
 tile and for grouting the floors, and the very best 
 quality of Keene's Imported Cement for filling the 
 joints in the wall tiling. 
 
 Sand. — Clean, sharp grit sand, free from all salt, 
 loam or other matter, and perfectly screened before 
 mixing with the cement, should always be used. 
 
 Mortar. — For floors or vitrecus tiles, should be com- 
 posed of equal parts of cement and sand, and for wall 
 tiles one (1) part of cement and two (2) parts sand. 
 The mortar should not be too wet, but should be rather 
 stiff, and should always be used fresh, as mortar, when 
 allowed to set before using, loses a portion of its 
 strength. 
 
 Soaking, — Tiles must always be thoroughly soaked 
 in water before setting,, which makes the cement unite 
 to the tiles. 
 
 The Tiles for the Floors are first laid out to ascer- 
 tain if they are all right and compared with the plan 
 provided for laying the floors. Strips are then set, 
 beginning at one end of and in the centre of the room, 
 and level with the intended finished floor line. Two 
 sets of guide strips running parallel about 18 to 30 
 
HOW TO USE THEM 
 
 487 
 
 inches apart should be set first. (See Pig. 38.) The 
 mortar is then spread between them for about six to 
 ten feet at a time, and level with a screed notched at 
 each end^ to allow for the thickness of the tiles. The 
 tiles are placed upon the mortar, which must be stiff 
 enough to prevent the mortar from working up be- 
 
 Y / . V V 
 
 < X X 
 r V r V 
 
 1 
 
 1 1 
 
 H • 
 'l 1 
 
 
 
 
 t 1 
 
 V Y 
 « t 
 
 V y 
 
 X A 
 
 i 
 
 i 
 
 \X X 
 
 
 
 i\ I r 
 1 > 1 
 
 X >i ! 
 
 ! 
 
 
 
 --. > ■ 
 
 
 » 1 
 
 c -\ >' 
 
 V > ' > 
 
 ' N ' N' >-.-•' .1 • r • • 
 
 Fig. 38. 
 
 tween the joints. The tiles are to be firmly pressed 
 into the mortar and tamped down with a block and 
 hammer until they are exactly level with the strips. 
 When the space between the strips is completed, the 
 strips on one side of the tile is moved out 18 to 30 
 inches and placed in proper position for laying an- 
 other section of tile, using the tiles which have been 
 
488 CEMENTS AND CONCRETES 
 
 laid for one end of the screed^ and the laying of the 
 tile continued in the same manner until the floor is 
 , finished. When the cement is sufficiently set^ which 
 should be in about two days, the floor should be well 
 scrubbed with clean water and a broom, and the joints 
 thoroughly grouted with pure cement (mixed with 
 water to the consistency of cream). As soon as this 
 begins to stiffen, it must be carefully rubbed off with 
 sawdust or flne shavings and the floor left perfectly 
 clean. 
 
 Ceramics, — The foundation and cement mortar for 
 ceramics are the same as for plain or vitreous floors, 
 and the guide strips used in the same manner. Tlu 
 cement mortar is then spread evenly and the tile sheets 
 laid carefully on it with the paper side up. After the 
 batch is covered, the tile setter should commence to 
 press the tile into the mortar, gently at first, firmly 
 afterwards, using block and hammer, thus leveling 
 the tile as correctly as possible. The tile should be 
 beaten down until the mortar is visible in the joints 
 through the paper ; however, without breaking it. The 
 pa])er is then moistened, and after it is well soaked 
 and can be easily removed, it is pulled off backwards, 
 starting from a corner. After removing the paper, the 
 tile should be sprinkled with white sand before fin- 
 ishing the beating, so that the tiles will not adhere to 
 the beater, owing to the paste which is used in mount- 
 ing them. Corrections of the surface are then made 
 by leveling it with block and hammer. The filling of 
 the joints and cleaning of the surface is a delicate op- 
 eration, as the looks of this work depends largely upon 
 it. The joints are to be filled with clean Portland 
 ceraent mixed with water. This mixture is forced into 
 
HOW TO USE THEM 489 
 
 the joints with a flat trowel (not with a broom, which 
 often scrapes out the joints). After the joints are 
 
 SCRtBQ 
 
 ^concrete: 
 Fig. 39. 
 
 fiHed, the surplus cement is removed from the sur- 
 face by drawing a wet piece of canton flannel over it. 
 
 Fig. 40. 
 
 This piece of cloth must be washed out frequently with 
 clean Avater. After the floor is cleaned, it should be. 
 
490 CEMENTS AND CONCRETES 
 
 allowed to stand for a day or two^ when the whole 
 floor is to be rubbed with sharp sand and a board of 
 soft lumber. This treatment, which the last traces of 
 cement, is preferable to the washing off with an acid 
 solution, as it will not attack the cement in the joints. 
 In laying the tile sheets on the cement, care should be 
 taken to have the widths of joints spaced the same as 
 the tile on the sheets to prevent the floor having a block 
 appearance. 
 
 Fig. 41. 
 
 The Tiles for the Walls or Wainscoting are first laid 
 out and compared with the plan provided for setting 
 them. Guide strips are then placed on the wall paral- 
 lel and about two feet apart, the bottom one being so 
 
HOW TO USE THEM 
 
 491 
 
 arranged as to allow the base to be set after the body 
 is in place. (See Fig. 40.) When "a cove base is used 
 it ma}^ be necessary to set it firsts but in all cases must 
 be well supported on the concrete. (See Fig. 41.) The 
 strips must be placed plumb and even with the intend- 
 ed finished wall line. The method of setting wall tile 
 is governed to some extent by the conditions of the 
 wall on which they are to be set^ and must be decided 
 by the mechanic at the time, which process he will 
 use, whether buttering or floating, as equally good 
 work can be done by either, by following the instruc- 
 tions, as stated below. 
 
 Floating Wall Tile. — The mortar is spread between 
 the guide strips for about five feet at a time and lev- 
 elled with a screed notched at each end to allow for 
 the thickness of the tile. (See Fig. 39.) The tiles are 
 placed in position and tamped until they are firmly 
 united to the cement and level with the strips. When 
 the space between the strips is completed, which should 
 be one side of the room, the strips are removed and 
 the work continued in the same manner until com- 
 pleted. When the tiles are all set, the joints must be 
 carefully washed out and neatly filled with thinly 
 mixed pure Keene's Cement, and all cement remaining 
 on the tile carefully wiped off. 
 
 Buttering Wall Tiles.\i — The cement mortar is spread 
 on the back of each tile, and the tile placed on the 
 wall, and tapped gently until firmly united to the wall 
 and plumb with the guide strips. When the tiles are 
 all set, the joints must be carefully washed out and 
 filled with Keene's Cement, and the tiles cleaned as 
 directed above. 
 
 When fixtures of any kind are to be placed on the 
 
492 CEMENTS AND CONCRETES 
 
 tile work^ such as plumbing in bathroom, provision 
 should be made for them by fastening wood strips on 
 the wall before the rough or first coating of cement 
 mortar is put on, the strips to be the same thickness 
 as the rough coating. The tiles can be placed over 
 the strips by covering them with cement mortar, and 
 when thoroughly set, holes can be bored in the tiles for 
 fastening the fixtures without injuring the tiling. 
 
 Hearth and Facing Tile are set in the same manner 
 as for floors and walls. 
 
 Cleaning. — It is absolutely necessary to remove with 
 sawdust, and afterwards with a flannel cloth and wa- 
 ter, all traces of cement which may have been left on 
 the surface of the tile, as it is hard to remove after it 
 is set. 
 
 After thoroughly cleaning the fioor^ it should be 
 covered with sawdust and boards placed on the floor 
 for several days where there is walking upon it. 
 
 A w^hite scum sometimes appears on the surface of 
 the tile, caused by the cement. This can generally be 
 removed by washing frequently with plenty of soap 
 and water. If this does not remove it, then use a weak 
 solution of 15 parts muriatic acid and 85 parts wa- 
 ter, which should only be allowed to remain on the 
 tile for a few minutes, and then thoroughly washed 
 off. 
 
 Cutting of Tile. — When it is found necessary to cut 
 tile the following directions are given : 
 
 TooZ5.i/— The chisels used should be made of the best 
 tool steel, and should always be sharp. They should 
 be of small size, the edge not being wider than one- 
 fourth inch. The hammer should be light, weighing 
 about six ounces, having a slender handle. After the 
 
HOW TO USE THEM 
 
 493 
 
 exact shape of the tile has been determined, lines 
 should be drawn on the surface of the tile with a lead 
 pencil, giving the exact direction of the cut desired. 
 This line should be folloAved with the chisel, which is 
 held at right angles with the surface, the hammer 
 giving the chisel sharp^ decisive raps. After the line 
 has been repeatedly traversed with the chisel, a few 
 sharp blows against the back of the tile opposite the 
 mark on the face will break it at the place thus 
 marked. 
 
 To cut glazed or enamel tiles, they should be 
 scratched on the surface with a tool at the place where 
 it is desired to break them, and then gently tapped 
 on the back opposite the scratch. 
 
 Caution should be used not to allow any one to 
 walk upon or carry anything heavy over the floor, or 
 have any pounding about wall work for several days, 
 or until the tiles are flrmly set. Unless these precau- 
 tions are taken it will be impossible to guarantee a 
 first-class job. Tile work is frequently condemned 
 when the fault lies with the rush of other contractors to 
 finish their work. 
 
 Laying Tile on Wood. — A new material called 
 ''Monolith/' manufactured by The Wisconsin Mantel 
 & Tile Co., that enables the workman to lay tiles on 
 a wooden floor. There are many places where tile 
 could be used, but on account of the added weight to 
 the floor by the use of cement, concrete foundation, it 
 is impracticable to lay in many places, but by the use 
 of Monolith, the only weight that is added is the tile 
 itself and the Monolith bed it is laid in. Both ma- 
 terials are only five-eighths of an inch in thickness 
 when laid. 
 
CEMENTS AND CONCRETES 
 
HOW TO USE THEM 495 
 
 The illustration, Fig. 42, shows the method of laying 
 the tile. The paper to which the small pieces of tiles 
 are glued is seen on top of tiles. The dark part shows 
 the patent cement, or Monolith. 
 
 I show herewith^ at Nos. 43 and 44, twelve designs 
 for decorative borders of various kinds, and in 45 
 and 46 I show two designs well suited for vestibules, 
 store entrances or for hearths in fire-places. 
 
 Good Concrete. — In determining the proportions of 
 the aggregates and cement for a certain piece of work, 
 it is necessary usually to take samples of the broken 
 stone (or gravel) and sand which are most available 
 to the site and make measuren;ients of the percentage 
 of voids in the stone w^hich must be filled by the sand 
 and the percentage of voids in the sand which must 
 be filled by the cement. This is done by taking a 
 cubic foot box and filling it with broken stone in a 
 thoroughly wet state. The box is then filled with as 
 much water as is required to completely fill it, in addi- 
 tion to the stone, which upon being poured off gives 
 the relation between the volume of the voids and the 
 volume of the stone. The required amount of local 
 sand thus determined is then measured out and placed 
 in the box with the stone in a damp state. Water is 
 then used to determine the percentage of voids left in 
 the sand, which gives the approximate amount of 
 cement required, although an excess of cement is al- 
 most invariably used. Engineers everywhere differ 
 regarding the best proportion to be used, but in gen- 
 eral the above test^ roughly made, will determine it 
 well enough. The proportions which are most univer- 
 sally used are as follows: 1 cement, 2 sand, 4 broken 
 stone; where extremely strong work is desired. Tests 
 
496 
 
 CEMENTS AND CONCRETES 
 
 BoROEft No. 413 
 
 >• . . . 'VA . ••••• ^ , A* . •••••• ^ A/^i 
 
 ^^^^^^^^^^^^ 
 
 Fi^. 43. 
 
HOW TO USE THEM 
 
 497 
 
 Fig-. 44, 
 
498 CEMENTS AND CONCEETES 
 
 show that a 6-inch thickness of 1-2-4 concrete properly 
 made is waterproof up to about 50 pounds to the square 
 inch. This concrete is frequently used for facing 
 dams. 1-3-6 is the proportion generally used for the 
 interior of dams and large structures. It is entirely 
 suitable for large foundations. 1-4-8 is frequently 
 used for foundation work^ and when properly mixed 
 
 Fig. 45. 
 
 makes good concrete, although it is about the limit 
 of what is considered good work, and would not be 
 suitable for very important structures. 1-5-10 is equal 
 to any concrete made with natural cement. It is a 
 well-known fact that the volume of concrete when 
 mixed with water is somewhat less than the volume of 
 the aggregate and cement before mixing. The con- 
 tractors' rule is that the volume of mixed concrete is 
 
HOW TO USE THEM 
 
 499 
 
 equal to the volume of the stone plus one-half to one- 
 third the volume of sand. 
 
 There has been much discussion among engineers 
 and others as to the amount of water that should be 
 added to the aggregates and cement for making the 
 best concrete, and while it is not the purpose of this 
 paper to enter into this controversy, it might be said 
 that the modern tendency is toward wet concrete. The 
 old way was to add just enough water so that when all 
 
 Fig. 46. 
 
 the concrete was in the form and tamped, it would 
 ^how moisture on the surface. The tamping is a very 
 important part of the operation, and the quality of 
 the work is dependent upon how well this is super- 
 intended, as unless it is well and thoroughly done the 
 concrete is liable to be honeycombed and imperfect, 
 especially near the forms. With the growth of the 
 
500 CEMENTS AND CONCRETES 
 
 use of concrete the old method of putting it in the 
 forms nearly dry and depending on tamping to con- 
 solidate it has been more or less abandoned, and the 
 more modern way is to put the concrete in quite wet, 
 as less tamping is required and much labor and ex- 
 pense saved. One of the great objections to this 
 scheme is that if care is not taken the water will tend 
 to wash the cement from the stone and sand; in other 
 words, unmix it. However, it may be said that it 
 is now generally understood that rather wet concrete 
 properly handled makes better work. The amount of 
 water to be added to the aggregates and cement va- 
 ries from 1 water to 3 cement by measurement to 12 
 per cent of water by weight. Mr. Carey, of New- 
 haven, England, says that 23 gallons water per cubic 
 yard of cement was the best mixture. Quite frequent- 
 ly salt water is used in mixing concrete in cold weather 
 to prevent freezing, and it seems to have no ill effects 
 on the resulting mixture. 
 
 Reinforced Concrete, — Up to the last few years the 
 use of concrete as a building material was chiefly con- 
 fined to the construction of foundations, piers, reser- 
 voir dams and similar purposes, in which the stresses 
 to be met Avere almost entirely simple pressures. In- 
 deed, even fifteen years ago, many engineers looked 
 askance on the use of concrete for arches, considering 
 it for this purpose much inferior to brick. Much of 
 the caution shown in extending the use of this valua- 
 ble material doubtless arose from the frequency with 
 which concrete masonry exhibited unsightly cracks, 
 due largely to the material being allowed to get too 
 dry while hardening. At the same time, careful ex- 
 amination has shown that cracks of the same char- 
 
HOW TO USE THEM 
 
 501 
 
 acter are common in masonry of all kinds, but are 
 unnoticed, because they follow the regular joints of 
 the structure ; whereas, on the smooth uniform sur- 
 face of the concrete, cracks of much less significance 
 are immediately visible. 
 
 The plan of reinforcing the material with metal, of 
 which several systems have been introduced during 
 the last four years, has greatly extended the possible 
 use of concrete ; and it appears that in many cases a 
 reinforced concrete bridge may compete, even in first 
 cost, with a steel girder; while as regards upkeep, it 
 has, of course, many advantages. Small bridge cul- 
 verts of this material were extensively used by Rus- 
 sian engineers in building the Manchurian Railway. 
 For openings of some 7-foot span, fiat slabs of con- 
 crete reinforced with rails were used, the thickness 
 being 8% inches. A similar system was used for spans 
 up to 21 feet, the concrete, however, being thickened 
 at the center as the span increased, the depth at this 
 point being 2 feet 6^ inches for the 21-foot span, and 
 proportionately less for smaller openings. The thick- 
 ness at the bearings was, however, the same in all 
 cases, viz., 8Vt inches. The line was thrown over the 
 spans as little as seven days after completion. The 
 concrete consisted of one part cement, two sand and 
 five broken stone. The system in this case had great 
 advantages, as stone for masonry was unobtainable, 
 and could, moreover, only be used for arches, which 
 would have necessitated the use of higher embank- 
 ments than were required with the ferro-concrete, used 
 as described. Much larger spans have, of course, been 
 built than those mentioned. One, of 153-foot span, 
 carrying four main line tracks, has recently been 
 
502 
 
 CEMENTS AND CONCRETES 
 
 built for the Lake Shore and Michigan Southern Rail- 
 road, while Mr. Edwin Thacker, M. Am. Soc. C. E., 
 states he considers the system feasible for spans up 
 to 500 feet, and has actually got out designs for a 
 span 300 feet, the cost comparing favorably with that 
 of a steel bridge. 
 
 One great drawback to the extension of the system 
 lies in the difficulty in proportioning structures thus 
 built in a thoroughly rational manner. In the case of 
 steel bridges certain simple assumptions as to the 
 elasticity and strength of the material suffice. These 
 assumptions are doubtless not absolutely exact, but are 
 sufficiently near the truth for practical purposes. The 
 elastic properties of concrete are, however, very dif- 
 ferent from those of steel; Hooke's law is not even ap- 
 proximately correct, and, moreover, the material al- 
 ways takes a permanent set when first loaded. The 
 true distribution of the stress and strain on a concrete 
 beam is thus a much more complicated matter than it is 
 in the case of a steel joist,, in which it is permissible, 
 within working limits of stress, to assume the accuracy 
 of Hooke's law. The assumption generally made in 
 the case of ferro-concrete is that plane sections of a 
 concrete beam remain plane after bending. This pos- 
 tulate is, of course, that commonly made in propor- 
 tioning steel work ; and in the latter case, stress being 
 proportional to strain, the usual formula for the work- 
 ing strength of beams is readily reduced. In the case 
 of concrete, however, the stress-strain curve is much 
 more complex. Nevertheless, M. Considere has shown 
 that by making experiments on concrete in simple ten- 
 sion and compression, and plotting the corresponding 
 stress-strain curves, it is possible to deduce from these 
 
HOW TO USE THEM 
 
 503 
 
 with fair accuracy the load-deflection curve of a ferro- 
 concrete beam. 
 
 This method, though logical, leads, however, to no 
 simple formula for the strength; and in applying this 
 method the working load of any particular concrete 
 beam would have to be deduced by the tedious proc- 
 ess of scaling off the stress-strain curves at a num- 
 ber of points, and combining the results. A further 
 question arises as to whether this stress-strain curve 
 should be the initial stress-strain of the concrete, or 
 that obtained after repeated loadings. Probably the 
 latter is the best to choose, but in that case it by no 
 means follows that the metal reinforcement is free 
 from initial stresses when the load is applied to the 
 beam ; and if the metal is subject to initial stress, it is 
 obvious that similar ones must exist in the concrete. 
 In fact, M. Considere has shown that this is necessarily 
 the case in any circumstances, since, if the concrete is 
 allowed to harden under water, it tends to expand, 
 * and this expansion is resisted by the metal reinforce- 
 ment. If, on the other hand, the hardening takes 
 place in air the concrete tends to contract; and this 
 contraction being again resisted by the metal, a series 
 of fine hair cracks are produced which, visible at low 
 loads, are readily detected on the tension side of a 
 heavily loaded ferro-concrete beam. 
 
 In view of the uncertainties introduced by the dif- 
 ferent factors above mentioned, it is really questionable 
 whether, after all^ the theoretically objectionable for- 
 mula of M. Hennebique is not as good as any other. 
 The latter all involve a preliminary calculation of the 
 position of the neutral axis, which varies with the per- 
 centage of metal used^ and with the type of stress- 
 
504 
 
 CEMENTS AND CONCRETES 
 
 strain curve assumed for the concrete ; and also with 
 the maximum stress at any particular section. Thus, 
 in a centrally-loaded beam, its position at the ends is 
 entirely different from what it is at the centre. M 
 Hennebique, on the other hand^ makes no attempt tc 
 locate this neutral axis, and simply assumes that one- 
 half of his beam resists compression, and that the 
 stress is uniformly distributed over this half. The 
 moment of this compression about the centre of the 
 section equates to half the moment due to the load, 
 and the other half of the moment due to the load he 
 equates to the moment about the centre of the section 
 of the tensile stress on the metal reinforcement. The 
 working strength of concrete in compression, he takes 
 as 350 pounds per square inch, and neglects entirely its 
 strength in tension. The working tensile stress on the 
 steel reinforcement he takes as 14,000 pounds per 
 square inch. This method is, of course, totally illogi- 
 cal, yet many thousand cubic yards of ferro-concrete 
 have been successfully designed on these lines; and a 
 comparison of the strength of ferro-concrete beams 
 as calculated by this formula, and by those of a more 
 rational type, shows very little difference between the 
 two for a considerable range of metal to concrete. On 
 the other hand, it must not be forgotten that formulae 
 which are non-rational in form are always risky when 
 applied to extreme conditions. 
 
 Concrete being as weak in shear as in tension, pro- 
 vision is also required to take the shearing stresses. 
 Some American designers have to this end patented 
 special forms of reinforcement bar, in which each main 
 tension bar has projecting upward from the ties in- 
 clined at an angle of 45 degrees. These extend to the 
 
HOW TO USE THEM 
 
 505 
 
 top of the bar and take the tensile stresses arising 
 from the shear. The corresponding compressive stress 
 at right angles to this is carried by the concrete. The 
 system is doubtless efficient^ and on large spans, where 
 weight must be reduced to a minimum it may have 
 some advantage; but in work of ordinary proportions 
 it seems to be little superior to the Hennebique sys- 
 tem, in which the necessary strengthening is provid- 
 ed by stirrups of flat iron bent into a U shape. The 
 main reinforcing bars rest in these stirrups at the 
 lower ends. The spacing of the stirrups depends upon 
 the 'Sveb stresses'' to be taken, which can easily be 
 calculated by assuming the reinforced beam to be a 
 latticed girder, the lower chord of which is represented 
 by the metal reinforcement, the upper one by the centre 
 of the compression half of the beam, while the stirrups 
 represent vertical ties, which may be taken as con- 
 nected together at top and bottom by inclined imag- 
 inary struts. The advantage of this simple method of 
 reinforcing for shear lies in the possibility of using 
 common rolled sections for the whole of the rein- 
 forcement. 
 
 M. Hennebique constructs most of his ferro-concrete 
 work on the monolithic system, girders, piers, columns 
 and floors being solidly connected together. It is, 
 therefore, necessary to provide for the reversed bend- 
 ing moments over the point of support, which is done 
 by bending up half of the total reinforcement bars, 
 so that the ends of the span are close to the upper 
 surface of the beam, and thus in a position to take 
 the heavy tensile stresses which ensue at these points 
 when the monolithic system of construction is fol- 
 lowed. The exact calculation of the reactions and 
 
506 CEMENTS AND CONCRETES 
 
 bending moments here is impracticable, if not actually 
 impossible; and those engineers who attach much im- 
 portance to having all structures statically determinate 
 will doubtless object to the plan, but experience shows 
 that the advantages gained are very considerable. The 
 structure then resists as a unit;, and in particular its 
 rigidity is marvelous. 
 
 Some comparative tests on this point, made by the 
 Railway Company, showed that with a ferro-concrete 
 floor subjected to blows four times as heavy as were 
 applied to an equivalent floor constructed of brick 
 arches on steel joists, the deflection was only one- 
 seventh as great. 
 
 The extreme rigidity attainable with the monolithic 
 system of construction was also very evident in the 
 case of the large Hennebique bridge at Purfleet. Since 
 a structure fails by strain rather than by stress, the 
 small deformation noted with ferro-concrete are evi- 
 dent that as an average the material is relatively lit- 
 tle tried by the loads carried. It must, however, be 
 admitted that this low average strain is quite com- 
 patible with extremely severe strain at particular 
 points ; but it is, of course, the business of the designer, 
 by suitably disposing his material to avoid these pos- 
 sible local abnormalities. 
 
 Occasionally, doubts have been expressed as to 
 Avhether the metallic reinforcement may not suffer from 
 corrosion as time goes on. This would be extremely 
 dangerous if it occurred, since the metal being out of 
 sight, its loss of strength might remain undetected un- 
 til, some day, the structure might fall under its ordi- 
 nary working load. Fortunately, much evidence is 
 available to the effect that steel or iron thoroughly 
 
HOW TO USE THEM 
 
 507 
 
 imbedded in concrete is permanently protected from 
 rust. Americans, indeed, are so positive on this point 
 that they have recently constructed a number of reser- 
 voir dams in ferro-concrete. In some cases these have 
 been arched, but in others they have been straight. 
 The cross-section in the latter case is generally a hollow 
 triangle^ the sides of which are connected together by 
 diaphragm walls from point to point. The dam is also 
 anchored to its site^ though generally the weight pro- 
 vided is sufficient to make the structure safe against 
 overturning, quite apart from the help received from 
 the anchor-bars. 
 
 Progress in the use of reinforced concrete has been 
 somewhat slow in England. The railway engineers, in 
 view of their enormous responsibilities, have not un- 
 naturally hesitated to adopt a material in which it was 
 impossible to calculate the strength with accuracy, and 
 of which experience as to its reliability was very re- 
 cent. In the larger cities, moreover, its use has, quite 
 apart from this, been restricted by the inelastic na- 
 ture of the building regulations, which have been 
 reached upon the assumption that finality had been 
 reached in the matter of building construction. Hence, 
 permission to erect warehouses and factories in ferro- 
 concrete has alwaj^s been difficult — and often impossi- 
 ble — to obtain, though experience has shown that the 
 new material is most excellent as a fire-resister. At 
 the great Baltimore fire it was found that the concrete 
 exposed to the flames was seldom damaged to a greater 
 depth than one-half inch^ though projecting corners 
 suffered somewhat more, being rounded off by the 
 flames to a radius of about two inches, pointing to the 
 advisability of constructing the concrete with well- 
 
508 CEMENTS AND CONCRETES 
 
 rounded corners in the first instance. The only rea- 
 sonable grounds of objection to any proposed system 
 of building construction are its dangers from a struc- 
 tural sanitary or fire-risk point of view. As a result 
 of much investigation and experiment, the following 
 conclusions were arrived at for the guidance of the 
 designer and constructor of reinforced concrete : 
 
 1. AVhat drawings and details should be prepared 
 before work is commenced. 
 
 2. The nature of the materials which may be em- 
 ployed and the standards to which these should com- 
 ply, i. e., 
 
 (a) the metal in reinforcement, 
 
 (b) the matrix, 
 
 (c) the sand, 
 
 (d) the gravel, stone, clinker or other aggregate, 
 
 (e) water. 
 
 3. What are the proportions for concrete to be used 
 in different cases. 
 
 4. How the ingredients for concrete are to be mixed 
 and deposited on the work. 
 
 5. The distances to be allowed between the reinfor- 
 cing bars and what covering of concrete is necessary. 
 
 6. What precautions are necessary in the design and 
 erection of centring and false work, and how long the 
 whole or portion of centring and false work should re- 
 main in position. 
 
 7. The rules which should be used in determining 
 the dimensions of the several parts necessary for secur- 
 ity, and what safe stresses should be allowed. 
 
 8. The supervision necessary and the special matters 
 to which it should be directed. 
 
HOW TO USE THEM 
 
 509 
 
 9. The fire-resisting properties of reinforced con- 
 crete. 
 
 10. Its adaptability for structures where resistance 
 to liquid pressure is essential, and what special precau- 
 tions may be advisable under these conditions. 
 
 11. What are the necessary conditions for its perma- 
 nence; resistance to rusting of metal, disintegration of 
 concrete or effects of vibration. 
 
 12. The testing of the materials employed and of the 
 finished structures. 
 
 13. What provisions are desirable in Building Laws 
 or Government regulations relating to buildings and 
 other structures so far as these affect the use of rein- 
 forced concrete. 
 
INDEX 
 
 PA6B 
 
 MATERIALS : 
 
 Limes 27 
 
 Cements 30 
 
 Mortars 28 
 
 Sand 28 
 
 Plasters and laths 31 
 
 WORKMANSHIP: 
 
 External work 35 
 
 Internal work 37 
 
 SPECIFICATION CLAUSES: 
 
 Materials 42 
 
 Workmanship 43 
 
 PREPARATION OF BILL OF QUANTITIES: 
 
 Materials 46 
 
 Workmanship 46 
 
 Laths 48 
 
 TOOLS AND APPLIANCES : 
 
 Hoes and drags 50 
 
 The hawk 52 
 
 The mortar board , o . . . . 52 
 
 Trowels 52 
 
 Floats 52 
 
 Moulds 54 
 
 The pointer 54 
 
 The paddle 55 
 
 Stopping and picking out tools 55 
 
 Mitering rod 55 
 
 Scratcher 55 
 
 511 
 
512 INDEX 
 
 PAGti 
 
 TOOLS AND APPLIANCES.— Continued, 
 
 Hod 55 
 
 Sieve 56 
 
 Sand screens 56 
 
 Mortar beds 57 
 
 Slack box 57 
 
 Lathing 57 
 
 Lather's hatchet 58 
 
 Nail pocket 58 
 
 Cut-off saw 58 
 
 PLASTER, LIME, CEMENTS, SAND, ETC.: 
 
 Plaster of Paris 60 
 
 Quick and slow setting plaster 62 
 
 Testing 63 
 
 French plaster 65 
 
 Limes 65 
 
 Hydraulic limes 66 
 
 Calcination 69 
 
 Slaking : 70 
 
 Mortar 73 
 
 Hardening of mortar. . 78 
 
 Magnesia in mortars 82 
 
 Effects of salt and frost in mortar 84 
 
 Sugar with cement 86 
 
 Sugar in mortar 88 
 
 Lime putty 89 
 
 Setting stuff . 90 
 
 Haired putty setting 91 
 
 Lime water 91 
 
 Hair 91 
 
 Fibrous substitutes for hair 92 
 
 Sawdust as a substitute for hair 93 
 
 Sand 94 
 
 Mastic 96 
 
 Scotch mastic 96 
 
 Common mastic 97 
 
 Mastic manipulation „ 97 
 
INDEX 513 
 
 PAGE 
 
 PLASTER, LIME, CEMENT, ETC.— Continued. 
 
 Hamelein's mastic 97 
 
 Mastic cement 98 
 
 TERMS AND PROCESSES: 
 
 Three-coat work 99 
 
 First coating 99 
 
 Scratching ; . 100 
 
 Rendering • 102 
 
 Screeds 103 
 
 Floating 103 
 
 Flanking 106 
 
 Scouring coarse stuff Ill 
 
 Keying 112 
 
 Setting 114 
 
 Laying setting stuff 115 
 
 Scouring setting stuff 115 
 
 Troweling and brushing setting stuff 116 
 
 General remarks on setting 117 
 
 Common setting 119 
 
 Skimming 119 
 
 Colored setting 119 
 
 Gauged setting 120 
 
 Gauged putty set 120 
 
 Putty set 121 
 
 Internal angles 121 
 
 External angles 121 
 
 Skirtings 122 
 
 Two coat work 123 
 
 One-and-a-half coat work 123 
 
 Stucco 124 
 
 Old stucco 124 
 
 Common stucco 129 
 
 Rough stucco 129 
 
 Bastard stucco 130 
 
 Troweled stucco 130 
 
 Colored stucco 131 
 
 Method of working cements 131 
 
514 INDEX 
 
 PAGE 
 
 TERMS AND PROCESSES.— Continued. 
 
 White cement efflorescence 138 
 
 Cornice brackets 139 
 
 Cornices 140 
 
 Mitring 155 
 
 Mitre mould 156 
 
 Fixing" enrichments 159 
 
 Mitring enrichments . 160 
 
 Pugging 163 
 
 Sound ceilings 164 
 
 Cracked plaster work 165 
 
 Repairing old plaster , 165 
 
 Gauged work 168 
 
 Joist lines on ceilings 169 
 
 Rough casting 170 . 
 
 VARIOUS METHODS OF RUNNING COR- 
 NICES, CIRCLES, ELLIPSES AND OTHER 
 ORNAMENTAL STUCCO WORK: 
 
 Diminished columns 177 
 
 Column trammel 180 
 
 Constructing plain diminished columns 183 
 
 To set out the flutes of diminished columns. . . . 183 
 
 Constructing diminished fluted columns 185 
 
 Forming diminished fluted column by the rim 
 
 method 193 
 
 Running diminished fluted column by the Col- 
 lar method 196 
 
 Diminished fluted pilasters 200 
 
 Pannelled coves 200 
 
 Diminished mouldings 204 
 
 False screed method 204 
 
 Running double diminished mouldings 208 
 
 Diminished rule method 208 
 
 Top rule method 211 
 
 Cupola panels and mouldings 215 
 
 Panelled beams 220 
 
INDEX 515 
 
 PAGE 
 
 VARIOUS METHODS, ETC.— Continued. 
 
 Trammels for elliptical mouldings 220 
 
 Templates for elliptical mouldings 224 
 
 Plasterer's oval 228 
 
 Coved ceilings 233 
 
 Circle mouldings on circular surfaces 233 
 
 Forming niches 235 
 
 Running an elliptical moulding in situ 240 
 
 MISCELLANEOUS MATTERS: 
 
 Depeter 243 
 
 Sgraffitto 243 
 
 Fresco f 251 
 
 Fresco seeco 255 
 
 Indian fresco and. marble plaster 256 
 
 Scagliolia 260 
 
 Artificial marbles 262 
 
 Pick's neoplaster 263 
 
 Scagliolia manufacture 264 
 
 Mixing 270 
 
 Colors and quantities 272 
 
 Polishing white scagliolia 275 
 
 Polishing scagliolia 276 
 
 Marezzo 277 
 
 Granite finish 282 
 
 Granite plastering . 283 
 
 CEMENTS AND CONCRETES AND HOW TO 
 
 USE THEM: 
 
 Fine concrete 291 
 
 Matrix 293 
 
 Aggregate 294 
 
 Porous aggregates 295 
 
 Compound aggregates . 296 
 
 Sand and cement 297 
 
 Fire-proof aggregates 300 
 
 Voids in aggregates 302 
 
 Crushing strength of concrete 302 
 
516 INDEX 
 
 PAGE 
 
 CEMENTS AND CONCRETES.— Continued. 
 
 Water for concrete. 303 
 
 Gauging concrete 305 
 
 Ramming concrete 308 
 
 Thickness of concrete paving 309 
 
 Concrete paving 310 
 
 Eureka paving 312 
 
 Eureka aggregate 313 
 
 Eureka quantities 314 
 
 Levels and falls 315 
 
 Pavement foundations 316 
 
 Screeds and sections 318 
 
 Laying concrete pavements 320 
 
 Troweling concrete . 321 
 
 Grouting 322 
 
 Dusting 322 
 
 Temperature 322 
 
 Non-slippery pavements 323 
 
 Grooves and roughened surfaces 323 
 
 Stamped concrete 325 
 
 Expansion joints 325 
 
 Washing yards 328 
 
 Stable pavements 328 
 
 Concrete slab moulds 329 
 
 Slab making 330 
 
 Induration concrete slabs 330 
 
 Mosaic 331 
 
 Concrete mosaic , 333 
 
 Concrete mosaic laid in situ. 334 
 
 Storing cement . 337 
 
 Cement mortar 337 
 
 Mixing 338 
 
 Grout 339 
 
 Lime and cement mortar. 339 
 
 Cement mortar for plastering 339 
 
 Materials for making concrete sand 340 
 
 Gravel 341 
 
INDEX 517 
 
 PAGE 
 
 CEMENTS AND CONCRETES.—Continued. 
 
 Crushed stone 341 
 
 Stone verOTs gravel 342 
 
 Cinders 342 
 
 Concrete 343 
 
 Proportioning materials 344 
 
 Aggregate containing fine material 345 
 
 Mechanical mixers 346 
 
 Mixing by hand. . 346 
 
 Consistency of concrete 347 
 
 Use of quick setting cement 347 
 
 Coloring cement work 347 
 
 Depositing concrete 348 
 
 Retempering 349 
 
 Concrete exposed to sea-water 349 
 
 Concrete work in freezing weather 350 
 
 Rubble concrete 350 
 
 To face concrete 351 
 
 Wood for forms 352 
 
 Concrete sidewalks 352 
 
 Excavation and preparation of subgrade 353 
 
 The subf oundation 353 
 
 The foundation 353 
 
 The top dressing or wearing surface 354 
 
 Details of construction 384 
 
 Concrete basement floors 358 
 
 Concrete stable floors and driveways 358 
 
 Concrete steps 359 
 
 Reinforced concrete fence posts 360 
 
 Reinforcement 362 
 
 Concrete for fence posts 362 
 
 Molds for fence posts 363 
 
 Attaching fence wire to posts 365 
 
 Molding and curing posts 365 
 
 Concrete building blocks , 368 
 
 Tests of concrete fence posts 370 
 
 Retempering \ 378 
 
518 INDEX 
 
 PAGE 
 
 CEMENTS AND CONCRETES.— Continued. 
 
 Some practical notes 380 
 
 Concrete stairway and steps 387 
 
 Cast concrete stairs 389 
 
 Test of steps 390 
 
 Concrete stairs formed in situ 391 
 
 Setting out old stairs 391 
 
 Nosings and risers 392 
 
 Framing staircases 394 
 
 Centring for landings and soffits 396 
 
 Waterproof centring 397 
 
 Staircase materials 399 
 
 Filling in stairs 400 
 
 Finishing stairs 404 
 
 Non-slippery steps 405 
 
 Striking centrings 405 
 
 Concrete and iron. 406 
 
 Setting concrete soffits 408 
 
 Fibrous concrete 408 
 
 Polished soffits 409 
 
 Concrete staircases and fibrous plaster 410 
 
 Dowel holes 410 
 
 Cast steps 411 
 
 Treads and risers 412 
 
 Closed outer strings 413 
 
 Conciete floors 413 
 
 Plaster floors 415 
 
 Joist concrete floors 416 
 
 Caminus concrete cement 417 
 
 Concrete floors and coffered ceilings 418 
 
 Combined concrete floors and panelled ceilings . 419 
 
 Concrete and wood 420 
 
 Concrete drying 421 
 
 Concrete slab floors 423 
 
 Construction of slab floors 425 
 
 Hollow floors 427 
 
 Concrete roofs 428 
 
INDEX 519 
 
 PAGE 
 
 CEMENTS AND CONCRETES. —Continued. 
 
 Notes on concrete 429 
 
 Cast concrete 431 
 
 Concrete dressing 432 
 
 Mouldings cast in situ 438 
 
 Modelling in fine concrete 443 
 
 Concrete fountains 446 
 
 Concrete tanks 44S 
 
 Concrete sinks 443 
 
 Garden edging 443 
 
 Concrete vases 448 
 
 Concrete mantel pieces 449 
 
 Colored concrete 449 
 
 Fixing blocks 452 
 
 Typical system of reinforced concrete construc- 
 tions from various sources 452 
 
 Columns and piles 458 
 
 Floors, slabs and roofs 468 
 
 Beams 469 
 
 Arches 471 
 
 Lintels 473 
 
 Concrete walls 475 
 
 Strong rooms . 475 
 
 Concrete coffins and cementation 475 
 
 Tile fixing 477 
 
 Setting floor and wall file , , 479 
 
 Foundations 479 
 
 Lime mortar . . 480 
 
 Concrete 480 
 
 For floors 480 
 
 For wood floors 483 
 
 In old buildings 481 
 
 For hearths " 48"? 
 
 For walls 484 
 
 Cement 486 
 
 Sand 486 
 
 Mortar ....... 486 
 
INDEX 
 
 PAGE 
 
 CEMENTS AND CONCRETES.— Continued. 
 
 Soaking 486 
 
 Tiles for floors 486 
 
 Ceramics 488 
 
 Files for walls and wainscoting 490 
 
 Floating wall tile 491 
 
 Buttering wall tiles 491 
 
 Hearth and facing tile 492 
 
 Cleaning 492 
 
 Cutting of tile 492 
 
 Tools 492 
 
 Laying tile on wood 493 
 
 Good concrete 495 
 
 Reinforced concrete 500 
 
NOTICE 
 
 To the many workmen who are purchasing the publications under the 
 authorship of Fred T. Hodgson, and who we feel sure have been benefited 
 by his excellent treatises on many Carpentry and Building subjects, we 
 desire to inform them that the following list of books have been published 
 since 1903, thereby making them strictly up-to-date in every detail. All of 
 the newer books bearing the imprint of Frederick J. Drake & Co. are modern 
 in every respect and of a purely self -educational character, expressly isslied 
 for Home Study. 
 
 PRACTICAL USES OF THE STEEL SQUARE, two volumes, over 500 
 pages, Including 100 perspective views and floor plans of medium- 
 priced houses. Cloth, two volumes, price $2.00. Half leather. - 
 price $3.00. 
 
 MODERN CARPENTRY AND JOINERY, 300 pages, including 50 house 
 plans, perspective views and floor plans of medium and low-cost 
 houses. Cloth, price $1.00. Half leather, price $1.60. 
 
 BUILDERS' ARCHITECTURAL DRAWING SELF-TAUGHT, over 350 
 
 pages, including 50 house plans. Cloth, price $2.00. Half leather, 
 price $3.00. 
 
 MODERN ESTIMATOR AND CONTRACTORS' GUIDE, for pricing build- 
 ers' work, 350 pages, including 50 house plans. Cloth, price $1.50. 
 Half leather, price $2.00. 
 
 MODERN LOW-COST AMERICAN HOMES, over 200 pages. Cloth, price 
 $1.00. Half leather, price $1.50. 
 
 PRACTICAL UP-TO-DATE HARDWOOD FINISHER, over 300 pages. 
 Cloth, price $1.00. Half Leather, price $1.50. 
 
 COMMON SENSE STAIR BUILDING AND HANDRAILING, over 250 
 pages, including perspective views and floor plans of 50 medium-priced 
 houses. Cloth, price $1.00. Half leather, price $1.50. 
 
 STONEMASONS' AND BRICKLAYERS' GUIDE, over 200 pages. Cloth, 
 price $1.50. Half leather, price $2.00. 
 
 PRACTICAL WOOD CARVING, over 200 pages. Cloth, price $1.50. Half 
 leather, price $2.00. 
 
 Sold by booksellers generally, or sent, all charges paid, upon receipt of 
 price, to any address in the world 
 
 FREDERICK J. DRAKE & CO. 
 
 Publishers 
 CHICAGO, : : : ; U. S. A. 
 
JfIMm Carpentry y 
 
 ADVANCED SERIES 
 
 ' Bjj jf red 2, ibodgson == 
 
 This is a continuation of Mr. Hodgson's first volume on Modern 
 Carpentry and is intended to carry the student to a higher plane 
 than is reached by the first volume. The first volume of this series 
 
 may be considered as the al- 
 phabet of the science of car- 
 pentry and joinery, v^hile the 
 present volume leads the stu- 
 dent into the intricacies of the 
 art and shows how certain 
 difficult problems may be solved 
 with a minimum of labor. 
 Every progressive workman — 
 and especially those who have 
 purchased the first volume of 
 this series — cannot afford to be 
 without this volume, as it con- 
 tains so many things necessary 
 the advanced workman should 
 know, and that is likely to crop 
 up at any time during his daily 
 labors. The work is well illustrated with over 1 00 diagrams, sketches 
 and scale drawings which are fully described and explained in the 
 text. Many puzzling working problems are shown, described and 
 solved. This is truly a valuable aid and assistant for the progressive 
 workman. 
 
 300 pages, fully illustrated. 12mo, cloth, price, $1.00 
 
 Sold by Booksellers generally or sent postpaid to 
 any address upon receipt of price by the Publishers 
 
 FREDERICK J. DRAKE & CO. 
 
 PUBLISHERS CHICAGO, U. S. A. 
 
Cnnlrartor 0 (^nxtit 
 
 TO CORRECT MEASUREMENTS of areas and 
 cubic contents in all matters relating to buildings of any 
 kind. Illustrated with numerous diagrams, sketches and 
 examples showing how various and intricate measure- 
 ments should be takf^n :: :: :: :: :: :: :: :: :: 
 
 By Fred T. Hodgson, Architect, and W. N. Brown, C.£. and Quantity Surveyor 
 
 7|THIS is a real practical book, 
 ^ showing how all kinds of 
 odd, crooked and difficult meas- 
 urements may be taken to 
 secure correct results. This 
 work in no way conflicts with 
 any work on estimating as it 
 does not give prices, neither 
 does it attempt to deal with 
 questions of labor or estimate 
 how much the execution of cer- 
 tain works will cost. It simply 
 deals with the questions of 
 areas and cubic contents of any 
 given work and shows how 
 their areas and contents may 
 readily be obtained, and fur- 
 nishes for the regular estimator 
 the data upon which he .can 
 base his prices. In fact, the 
 work is a great aid and assist- 
 ant to the regular estimator 
 and of inestimable value to the 
 general builder and contractor. 
 
 12mo, cloth, 300 pages, fully illustrated, price - $1.50 
 
 Sold by Booksellers generally or sent postpaid to 
 any address upon receipt of price by the Publishers 
 
 FREDERICK J. DRAKE & CO. 
 
 PUBLISHERS CHICAGO, U.S.A. 
 
STEEL SQUARE 
 
 A TREATISE OF THE PRAGTiOAL USES OF 
 
 By FRED. T. HODGSON, Architect. 
 
 New and up-to-date. 
 
 Do not mistake this edition for the one published 
 over twenty years ago. 
 
 This is the latest practical work om 
 
 the Steel Square and its uses pub- 
 ished. It is thorough, accurate, cleai 
 and easily understood. Confounding 
 terms and phrases have been relig- 
 iously avoided where possible, 
 and everything in the book has been 
 made so plain that a boy twelve years 
 of age, possessing ordinary intelli- 
 gence, can understand it from begin- 
 ning to end. 
 
 It is an exhaustive work including 
 some very ingenious devices for laying 
 out bevels for rafters, braces and other 
 inclined work; also chapters on the 
 Square as a calculating machine, show- 
 ing how to measure Solids, Surfacea 
 and Distances— very useful to builders 
 and estimators. Chapters on roofing 
 and how to form them by the aid or 
 the Square. Octagon, Hexagon, Hip 
 and other roofs are shown and ex- 
 plained, and the manner of getting 
 tho rafters and jacks given. Chapters 
 on heavy timber framing, showing how 
 the Square is used for laying out Mor» 
 tises, Tenons, Shoulders, Inclined 
 Work, Angle Corners and similai 
 work. The work also contains a large number of diagrams, showing how 
 the Square may be used in finding Bevels, Angles , Stair Treads and bevel 
 cuts for Hip, valley, Jack and other Rafters, besides methods for laying 
 out Stair Strings, Stair Carriages and Timber Structures generally. Also 
 contains 26 beautiful halftone illustrations of the perspective and fioor plana 
 of 25 medium priced houses. 
 
 The work abounds with hundreds of fine illustrations and explana* 
 tory diagrams which will prove a perfect mine of instruction for th« 
 mechanic, young or old. 
 
 Two large volumes, 660 pages, nearly 600 illustrations, printed on • 
 superior quality of paper from new large type. 
 
 Price, 2 Vols., cloth binding o $2M 
 
 Price, 2 Vols., half-leather binding 3.00 
 
 Single Volumes, Part I, cloth l.OG 
 
 p^rt 1 .half- leather «, 1 .50 
 
 Part II, cloth l.or 
 
 Part II, one half-leather. 
 
 i.oa 
 
 SEND FOR COMPLETE ILLUSTRATED CATALOGUE FREE 
 
 FREDERICK J. DRAKE ®. 
 
 PUBLISHERS OF SELF-EDUCATIONAL BOOKS 
 CHICAGO, ILL, 
 
 CO. 
 
THE) 
 
 UP=TO=DATE 
 HARDWOOD 
 FINISHER 
 
 IN TWO PARTS 
 
 By FRED T. HODGSON, Architect 
 
 Member of Ontario Association of Architects^ 
 Editor of '' National Builder and author of the 
 ''Modern Estimator and Contractors'* Guide,^^ 
 ''Modern Carpentry,''* "Architectural Drawing 
 Self-Taughtr ''^Practical Uses of the Steel 
 Square,^'' etc, 
 
 PART ONE, giving rules and methods for working hardwoods, with 
 description of tools required, the methods of using, and how to 
 sharpen and care for them, including saws, planes, files, scrapers, 
 chisels, gouges and other wood- worliing tools. How to choose hard- 
 woods for various purposes, and how to worit and properly manage 
 veneers. The proper use of glue, directions for preparing glue, blind 
 or secret nailing, how done and how finished. How to sliarpen 
 and use scrapers of various forms, with illustrations showing the 
 tools and how to handle them properly, etc. 
 
 PART TWO treats on the filling, staining, varnishing, polishing, 
 gilding and enameling woodwork of all kinds of woods. It also 
 treats on renovating old work, repolishing, re varnishing and 
 wood-finishing generally. There is a short treatise en dyeing woods 
 in various colors for inlaying and marquetry work, with rules for 
 making staining, dyes, fillers, and polishes of various kinds, French 
 polishing, hard-oil finish, rubbed and flat finish, treatment of hard- 
 wood floors, waxing, polishing, shellacking and general finishing of 
 hardwood in all conditions. 
 
 LARGE 12M0 CLOTH, 320 PAGES, 117 ILLUSTRATIONS. PRICE, $1.00 
 HALF LEATHER BINDING, GILT TOPS • . PRICE. $1.50 
 
 FREDERICK J. DRAKE ®l CO. 
 
 PUBLISHERS OF SELF-EDUCATIONAL BOOKS 
 
 CHICAGO, ILL. 
 
PRACTICAL BUNGALOWS 
 AND COTTAGES FOR 
 TOWN AND COUNTRY 
 
 THIS BOOK CONTAINS PERSPECTIVE 
 DRAWINGS AND FLOOR PLANS 
 
 OF ONE HUNDRED LOW AND MEDIUM PRICED HOUSES 
 RANGING FROM FOUR HUNDRED TO FOUR THOUSAND 
 DOLLARS EACH. ALSO TWENTY-FIVE SELECTED 
 DESIGNS OF BUNGALOWS FOR SUMMER AND COUNTRY 
 HOMES, FURNISHING THE PROSPECTIVE BUILDER 
 WITH MANY NEW AND UP-TO-DATE IDEAS AND SUG- 
 GESTIONS IN MODERN ARCHITECTURE 
 
 THE HOUSES ADVERTISED IN THIS BOOK ARE EN- 
 TIRELY DIFFERENT IN STYLE FROM THOSE SHOWN 
 IN HODGSON'S LOW COST HOMES 
 
 12 MO. CLOTH, 200 PAGES, 300 ILLUSTRATIONS 
 PRICE, POSTPAID $1.00 
 
 FREDERICK J. DRAKE & CO. 
 
 CHICAGO 
 
1bot 
 
 Steam 
 and 6as 
 
 By WM. DONJiLDSON 
 
 A MODERN treatise on Hot Water, Steam and Furnace 
 Heating, and Steam and Gas Fitting, which is in- 
 tended for the use and information of the owners of build- 
 ings and the mechanics who install the heating plants in 
 them. It gives full and concise information with regard 
 to Sieam Boilers and Water Heaters and Furnaces, Pipe 
 Systems for Steam and Hot Water Plants, Radiation, Radi- 
 ator Valves and connections. Systems of Radiation, Heating 
 Surfaces, Pipe and Pipe Fittings, Damper Regulators, Fit- 
 ters' Tools, Heating Surface of Pipes, Installing a Heating 
 Plant and Specifications. Plans and Elevations of Steam 
 and Hot Water Heating Plants are shown and all other sub- 
 jects in the book are fully illustrated. 
 
 256 pages, 121 illustrations, 12 mo, cloth, price, $1,50 
 
 Sold by Booksellers generally or sent postpaid to 
 any address upon receipt of price by the Publishers 
 
 FREDERICK J. DRAKE CO. 
 
 CHICAGO. U.S.A. 
 
Practical 
 llp-to-Date 
 PLUMBING 
 
 By 
 
 George B. Clow 
 
 Over 150 
 Illustrations 
 
 A PRACTICAL up-to-date work on Sanitary Plumbing, com- 
 prising useful information on the wiping and soldering of 
 lead pipe joints and the installation of hot and cold water and 
 drainage systems into modern residences. Including the 
 gravity tank supply and cylinder and tank system of water 
 heating and the pressure cylinder system of water heating. 
 Connections for bath tub. Connections for water . closet. 
 Connections for laundry tubs. Connections for wash-bowl or 
 lavatory. A modern bath room. Bath tubs. Lavatories. 
 Closets. Urinals. Laundry tubs. Shower baths. Toilet 
 room in office buildings. Sinks. Faucets. Bibb-cocks. Soil- 
 pipe fittings. Drainage fittings. Plumber's tool kit, etc., etc 
 256 pages, 180 illustrations. 
 
 12 Mo. Cloth . c $1.50 
 
 Sold by Booksellers generally or sent postpaid to 
 any address upon receipt of price by the Publishers 
 
 FREDERICK J. DRAKE <IL CO. 
 
 Chicago, U. S. A. 
 
GETTY CENTER LIBRARY 
 
 3 3125 00798 1778