Class ._7IcI/^,e^ Book V (a. COPYRIGHT DEPOSIT. -y* \- ; tr V ■«! ,** -. X BY THE SAME AUTHOR. Hritbrnetic of leiectncit?^ A Complete and Indispensable vade mecum for amateur, student, and electrical engineer. Fully Illustrated. Price, $ 1 .OO. Home Experiments in Science. 252 Pages. 96 Illustrations. Price, $1.50. "Rubber hand stamps ***** flDanipulation of IRubber A PRACTICAL TREATISE ON THE MANUFACTURE OP INDIA RUBBER HAND STAMPS, SMALL ARTICLES OF INDIA RUBBER, THE HEKTOGRAPH, SPECIAL INKS, CEMENTS, AND ALLIED SUBJECTS BY T. O'CONOR SLOANE, A.M., E.M., Ph.D. Author of 'Home Experiments in Science," "Arithmetic of Electricity," etc. KULLV^ ILLUtSTi^ATED MAR 4 lOOI^j ^- YORK NORMAN W. HENLEY & CO. 150 NASSAU STREET 1891 -Z- Copyright, 1890, by NORMAN W; HENLEY & CO, PREFACE. The present work hardly needs a preface. The object is to present in the simplest form the subject of the manipulation of India rubber. To mould and cure the mixed gum but few appliances are needed, and these can be made at home. The arti- cles produced are of more than ordinary utility. These two facts give value to the art and furnish a raison cVetre for this book. If its instructions do not prove practical it will have missed its object. For some reason the methods of moulding the material are not generally known. Experiment has taught many the futility of attempting to melt and cast it. While thus intractable by the usual meth- ods, it is the most plastic of materials when prop- erly treated. Its power of reproducing the finest details of a mould, of entering all the intricacies and undercuttings of a design, cause one to feel a peculiar pleasure in working with so responsive a material. It is not saying too much to affirm that to some readers this book will disclose a long hidden secret. To make it more generally useful it is writ- iv PBEFACE. ten for such readers, to meet the want of those knowing of the subject. It was 'felt that in follow- ing this course, and in treating the subject from its first steps, including the simplest as well as most advanced methods, the book would appeal to a larger body of readers. The allied subjects to which some chapters are devoted will be acceptable to many readers. The hektograph is given in several modifications. A substitute for rubber stamps which stands the severe usage of the Post Office has very distinct merits, and the manufacture is accordingly described in detail. Cements and inks embody many special formulae. In the last chapter inter- esting and practical notes will be found. For the use of certain cuts we are under obliga- tions to the Buffalo Dental Manufacturing Co.. Messrs. E. k F. X. Spon & Co., and to Mr. L. Spang- enberg. COXTEXTS. CHAPTER I. THE SOURCES OF INDIA KUBBER AI^'D ITS HISTORY. The Trees — The Sap — Caoutchouc — Early Uses by the Indians — First knowledge of it in Europe — Good- year, Day, and Mackintosh 9 CHAPTER II. THE NATURAL HISTORY AND COLLECTION OF EN'OIA RUBBER. African, East Indian, Central and South American Gums — Different Methods of Collection and Coagula- tion 15 CHAPTER III. PROPERTIES OF UNYULCANIZED AND VULCANIZED IN- DIA RUBBER. Properties of Unvulcamzed Rubber: its Cohesion and importance of this property — Analysis of Sap and Caoutchouc — Effects of Heat and Cold — Distillation Products — Vulcanized Rubber, and its Properties 24 CHAPTER IV. THE MANUFACTURE OF MASTICATED, MIXED SHEET AND VULCANIZED INDIA KUBBER. Treatment by the Manufacturer — Washing and Sheet- \ vi CONTENTS. ing — Masticating — Making Sheeting and Threads — Mix- ing — Curing — Coated Tissues 35 CHAPTER V. INDIA RUBBER STAMP MAKING, Mixed Sheet— Outlines of Moulding^Home-Made Vulcanizing Press — Further Simplifications of Same — Securing Accurate Parallelism of Platen and Bed — Dis- tance Pieces — Wood vs. Iron as Material for Press — Use of Springs on the Home-Made Press — Metal Flask Clamps — Large Gas-Heated Vulcanizing Press — Prepar- ing Type Model — The Matrix — Plaster of Paris and Dental Plaster as Substances for Matrices — Dextrine and Gum Arabic Solutions for Mixing Matrix — How Matrix is made — Shellac Solution for Matrix — Matrix Press and Spring-Chase — How to retard the Setting of Plaster of Paris — Oxychloride of Zinc Matrices — Talc Powder — Moulding and Curing the Stamp — Kerosene Heating Stove — Manipulation of Press — Degree of Heat — Simple Test of Curing — Time Eequired — Combined Matrix Making and Vulcanizing Apparatus — Chamber Vulcanizers — Object of Steam in Vulcanizers — Temper- ature Corresponding to Different Steam Pressures — Jacketed Vulcanizers — Gas Regulator — Flower Pot Vulcanizer — Fish Kettle Vulcanizer — Making Stamps without any Apparatus Whatever — Notes on Type, Quadrats and Spaces — Autograph Stamps 47 CHAPTER VI. INDIA RUBBER TYPE MAKING. Movable Type Making — Simple Flask and Matrix — Precautions as to Quantity of Rubber — Moulding — Curing — Cutting Tyi)e Apart — Special Steel Moulds — Wooden Bodied Type 73 COJsrTENTS. vii CHAPTER VII. THE MAKING OF STAMPS AND TYPE FROM VULCAN- IZED INDIA RUBBER. Ready Vulcanized Gum as Material for Stamps — Simplicity of the Process of Usino: It — Advantages and Disadvantages — Availability for Type 77 CHAPTER VIII. VARIOUS TYPE MATRICES FOR RUBBER STAMPS AND TYPES. Electrotype Matrices — Papier Mache — Flong Paste — Flong Matrices— Beating into Model — Drying and Bak- ing — Struck-up Matrices — Chalk Plates 80 CHAPTER IX. THE MAKING OF VARIOUS SMALL ARTICLES OF INDIA RUBBER. Suction Discs — Pencil Tips — Cane and Chair Leg Tips— Corks — Mats — Cord and Tubes — Bulbs and Hol- low Toys. 85 CHAPTER X. THE MANIPULATION OF SHEET RUBBER GOODS. Slieet Rubber Articles— Toy Balloons — Uses of Sheet Rubber in the Laboratory 94 CHAPTER XL VARIOUS VULCANIZING AND CURING PROCESSES. Liquid Curing Baths — Sulphur Bath — Haloids and Nitric Acid as Vulcanizers — Alkaline Sulphides — Sul- phur Absorption Process — Parke's Process. 97 CHAPTER XII. THE SOLUTION OF INDIA RUBBER. Mastication with Solvent — Peculiarities of the Pro- viii CONTEKTS. cess — Different Solvents and their Properties — Parafl&n — Vulcanized Rubber Solution — Aqueous Solution 108 CHAPTER XIII. EBONITE, VULCANITE AND GUTTA-PEKCHA. Ebonite and Vulcanite — Manufacture — Manipulation — Gutta-Percha and its Manipulation 108 CHAPTER XIV. GLUE OR COMPOSITION STAMPS. Substitute for Rubber Stamps— The United States Government Formula — Models and Moulds — Dating— Handles 118 CHAPTER XV. THE HEKTOGRAPH. How Made — The French Government Formula — Hek- tograph Sheets 121 CHAPTER XVI. CEMENTS. Marine Glue, and other special Cements 125 CHAPTER XVII. INKS. Hektograph, Stencil and Marking Inks — White and Metallic Inks 129 CHAPTER XVIII. MISCELLANEOUS. Preservation and Renovation of India Rubber — Burned Rubber for Artists — India Rubber Substitutes — General Notes of Interest 134 RUBBER HAND STAMP iMAKING AND THE MANIPULATION OF RUBBER. CHAPTER 1. THE SOURCES OF II^DIA RUBBER AKD ITS HISTORY, India rubber or caoutchouc is a very peculiar product, which is found in and extracted from the juice of certain trees and shrubs. These are quite numerous and are referred for the most part to the following families: Euphorbiaceaed, Urticaceaed, Ar- tocarpesed, Asclepiadaceaed, and Cinchonace^d. It is evident that a considerable number of trees are utilized in commerce for its production, and it is certain that it exists, quite widely distributed, in many cases as a constituent of the juice of plants not recognized as containing it. When an India rubber tree is tapped, which is effected by making incisions in the bark, the sap of the tree exudes. It is a milky substance and is collected in various ways; it may be in vessels of 10 RUBBER BAND STAMP MAKING clay, in shells, or in other receptacles by the india rubber hunters. If this substance is examined it is found to be of ver}' remarkable and characteristic constitution, resembling in its physical features ordinary milk. It is composed of from fifty to ninety per cent, of Avater, in which is suspended in microscopic globules, like the cream in milk, the desired caoutchouc or india rubber. If the juice is left to stand in vessels, like milk in a creamery, the globules rise to the surface, and a cream of india rubber can be skimmed off from the surface. If the juice is evaporated over a fire, the water escapes and the india rubber remains. By dipping an article repeatedly in the juice and drying it, a thick or thin coating of india rubber can be developed. Before the modern methods for the manipulation of the gum had been developed, and before the inven- tion of vulcanization, this method was adopted for the manufacture of shoes. The original "india rubbers " for protection of the feet in wet weather were made in this manner. A clay last was used, upon which the india rubber was deposited as described. The clay last was then broken out and removed. Great quantities of overshoes were thus made in South America, and many were exported to Europe. When caoutchouc has once been removed from this watery emulsion, which for all practical pur- poses is a solution, it cannot be restored to the former state of liquidity; it remains solid. It will AND THE MAN LP ULA TION OF R UBBER. 1 1 absorb a considerable quantity of water, but will not enter again into the quasi solution or combina- tion. This property of permanent coagulation, which interferes to a degree with its easy manipula- tion, was early discovered. In the last century quantities of the natural milk were exported to Europe to be used in what may be termed the nat- ural process of manufacture, because once solidified it could not be redissolved, and because the manu- facturers of those days had not the present methods of dealing with the apparently intractable gum. The natives of South America before the advent of Europeans, were familiar with the treatment of the juice by evaporation just described and used to make bottles, shoes and syringes of it for their own use. The name Siplionia applied to several species of rubber tree, and seringa (caoutchouc) and seringari (caoutchouc gatherer) in SjDanish recall the old Indian syringes and tubes. The gum is now collected for export in many parts of the world. South and Central America are, as they have always been, the greatest produ- cers. Some is collected in Africa, Java and India. The best comes from Para. However carefully treated a great difference is found in the product from different countries. The Brazilian india rub- ber, known as Para, from the port of shipment, ranks as the best in the market. Its history as far as recorded, does not go back of the last century. Le Oondamine, who explored the 12 RUBBER HAND STAMP MAKING Amazon River, sent from South America in 1736 to the Institute de France, in Paris, the first sample of india rubber ever seen in Europe. He accompanied the sample with a communication. He said that the Indians of that country used the gum in making seveml domestic objects of utility, such as vessels, bottles, boots, waterproof clothing, etc. He stated that it was attacked and to a certain extent dis- solved by warm nut oil. In 1751 and 17G8 other samples were received through MM. Fresnau and Maequer, who sent them to the Academy of Sci- ences, Paris, from Cayenne in Guiana. Although from this period numerous experiments were tried with the new substance little of impor- tance was done with it for many years. Its first use was to rub out pencil marks, whence it derived its name of '' india rubber. ^^ As late as 1820 this con- tinued to be its principal use. An interesting reminiscence of its early history is given by Joseph Priestley, the great English chemist of the last century, celebrated as the discoverer of oxygen. In 1770 he mentioned the use of the gum for erasing pencil marks, and speaks of its cost being three shillings, about seventy cents, for " a cubical piece of about half an inch.^^ As we have seen, its solubility was early studied. In 1761 Herissant added turpentine, ether and "huile de Dippel " to the list of solvents. In 1793 its solubility was utilized in France by Besson, who made waterproof cloth. In 1797 Johnson intro- AND THE MANIPULATION OF RUBBER. 18 duced for the same manufacture a solution in mixed turpentine and alcohol. The year IS'^O is the beginning of the period of its modern use on a more extended scale. Nadier developed the methods of cutting it into sheets and threads and of weaving the latter. Mackintosh in 1823 began the manufacture of waterproof cloth, using the solution of the gum in coal tar naptha, which was caused to deposit by evaporation a layer of the gum upon a piece of cloth which was covered by a second one. This protected the wearer from the gummy and sticky coating of raw india rubber. At the best the original Mackintoshes must have been very disagreeable articles for wear. In 1825 india rubber shoes of raw india rubber were imported from South America and formed for a while an important article of commerce. In 1839 Charles Goodyear, of Massachusetts, in- vented the art of vulcanizing, or combining india rubber with sulphur. It was patented on June 15, 1844, and covers only the manufacture of soft rub- ber. Vulcanite or hard rubber (whalebone rubber) is disputed as to its origin, its invention being assigned by some to Nelson Goodyear and by others to Austin G. Day, of Connecticut. Goodyear how- ever succeeded in obtaining a patent on May 6, 1851. Day obtained a patent on August 10, 1858. Vulcanization is the most important invention ever made in connection with india rubber and may fairly rank as one of the greatest discoveries of the 14 RUBBER HAND STAMP MAKING present century. It is claimed by the English, an inventor named Handcock being cited as the rival of Charles Goodyear. The latter inventor had as an associate Nathaniel Hayward, who is probably entitled to some of the credit. By vulcanization India rubber loses susceptibility to heat and cold, becomes non-adherent, and insol- uble in almost all substances. It is converted from a comparatively useless substance into one of wide applicability. The subject of india rubber is so interesting in its theoretical as well as practical bearings that it seems impossible that those who are workers in it should not feel an interest in its natural history. For such readers the chapter on the natural history and collection of india rubber has been written. As it is a product of widely separated lands on both hemispheres, and as it is yielded by an immense number of plants, it is impossible in the limits of a chapter to give a full outline of its natural history. The chapter in question is, therefore, with this apology, inserted where it belongs, near the begin- ning of the book. Those who are entirely practical may pass it over. There is no doubt that the few minutes necessary for its perusal will be bestowed upon it by some. CHAPTER IT. THE NATURAL HISTORY Ai^D COLLECTIOi^ OF INDIA RUBBER. African India rubber is mostly exported from the west coast. The belt of country producing it extends nearly across the continent. Those who are familiar with the India rubber plants of our conser- vatories are apt to think of the gum as the product of trees, but in Africa it is largely yielded by climb- ing plants of very numerous varieties, belonging generally to the Landolphia species. It is collected by the natives by careless or desultory methods, probably less advanced than the ways followed by the South Americans. Possibly its marked inferior- ity may be partly attributed to this. It is also sup- posed by many that, were the gathering restricted to the vine producing the best gum, better results would follow. As it is now all gums are mixed indiscriminately. African gum is of very inferior quality. The African india rubber vines grow often in dark moist ravines, where no valuable product other than themselves could be cultivated. They are entirely wild, The vines when cut exude an abun- 16 RUBBER HAND STAMP MAKING dance of sap, which differs from the South Amer- icau product in its quickness of coaguhition. As it escapes from the wound it at once solidifies and pre- vents the further escape of juice. The negroes are said to employ the following highly original method of collecting it. They make long gashes in the bark. As fast as the milky juice comes out they wipe it off with their fingers and wipe these in turn on their arms, shoulders, and body. In this way they form a thick covering of inspissated juice or caoutchouc over the upper part of their body. This from time to time is removed by peeling. It is then said to be cut up and boiled in water. This is one account. According to others the natives remove a large piece of bark, so that the juice runs out and is collected in holes in the earth or on leaves. Wooden vessels are said to be used else- where. Sometimes the juice is said to be collected upon the arms, the dried caoutchouc coming off in the shape of tubes. A clew to the inferiority of African India rubber is afforded by the statement that too deep a cut liberates a gum which deterior- ates the regular product if it mixes with it. The drying of the gum is thought to have much to do with its quality and it is highly probable that this affects the African product. Some samj^les seem to be partly decomposed they are so highly offensive in odor. The South American rubber is often dried in thin layers, one over the other, by a smoky fire, which may have an antiseptic effect upon the newly AND THE MANIPULATION OF RUBBER. 17 coagulated caoutchouc. No such process as far as known is used in Africa. The African india rubber appears under different names in commerce. T'rom the Congo region lumps of no particular shape called '' knuckles " ; from Sierra Leone smooth lumps, '^negro-heads/' and " balls " made up of small scrap ; from the Portu- guese ports 'thimbles/' ''nuts/' and '' negro- heads; " from the gaboon ''tongues; '' and from Liberia "balls are received." It is all character- ized by great adhesiveness and low elasticity. From Assam, Java, Penang, and Rangoon there is considerable gum exported. It is supposed to be the product of trees of the ficus species, in all these places, as it is known to be in Java and Assam. In the latter place rigid restrictions are imposed as far as possible upon the gathering. In the case^ of wild trees scattered through the forest the carrying out of these restrictions is not practicable. The trees are cut with knives in long incisions through the bark and the juice is collected in holes dug in the ground, or often in leaves wrapped up into a conical form, somewhat as grocers form their wrap- ping paper into cornucopia shape for holding sugar, etc. It has seemed reasonably certain that the india rubber producing plants might be cultivated with profit, and it is as certainly to be feared that without such cultivation they will become extinct. Efforts have been made in the direction of raising 18 RUBBER HAND STAMP MAKING them artificially but without much success. In Assam numerous experiments have been made to propagate the india rubber heaving Jicks tree. A o-ood instance of the ill effects of carelessness in the original gathering of the crop is afforded by the Bornese collectors. The source of Borneo india rubber is a variety of creepers. These are cut down and divided into short sections from a few inches to a yard in length. The sap oozes out from the ends. To accelerate its escape the pieces are sometimes heated at one end. It is coagulated by salt water. Sometimes a salt called ?iipa salt, ob- tained by burning a certain plant (nipafriiticans), is used for the purpose. In either case it is coagulated Tree Felled for Collection of India Rubber. into rough balls and masses. These masses are heavily charged with the salt water, often contain- ing as much as fifty per cent., and rarely much less than twenty per cent. Central America and Panama are great producers of the gum. In Panama the custom of felling tlie AND THE MANIPULATION OF BUBBER. 19 trees is often adopted. In this case grooves are cut around the prostrate trunk, and under each groove as the trunk lies on the ground a vessel is placed to collect the sap. Its coagulation is often effected by leaving it for a couple of weeks standing at rest in a hole, excavated on the surface of the ground, and covered over with leaves. The caoutchouc sepa- rates under these conditions. A quicker method, but one yielding an inferior product, is obtained by adding to the fresh juice some bruised leaves of a plant (ipomcea bona nox) which acts something like acid upon milk, in separating the desired solid matter or caoutchouc. A jelly like accretion satu- rated with blackish water is thus obtained. By working it together a blackish liquid is caused to escape, and comparatively pure gum is gradually obtained. As much as one hundred pounds of india rubber may be obtained from a single tree where this destructive system is employed. Fur- ther north, where a better counsel has prevailed, the trees are only tapped, and the india rubber hunter is satisfied if from a tree eighteen inches in diam- eter he obtains twenty gallons of sap, giving fifty pounds of gum. Even where tapping is done the tree is often destroyed by carelessness or ignor- ance. Two systems are followed in Xicaragua. The oper- ator ascends by a ladder if he has one, or in any case climbs as high as he well can and begins to make a long incision. Sometimes he carries one long straight 20 RUBBER II AND STAMP MAKING cut clear down to the ground. This is made the starting point for a number of side cuts, short, and running diagonally into it. This is also one of the Brazilian methods. The Nicaraguan sometimes also makes two spiral incisions, one right-handed and the other left-handed, crossing each other as they descend so as to divide the surface of the tree into roughly outlined diamonds. In either case the juice flows down to an iron spout, placed at the bottom of the tree, which spout leads to an iron pail. The milk is gathered and passed through a sieve, and coagulated in barrels by the ipomcea plant as before mentioned. This gives three grades of rubber. The bulk is obtained from the barrels and is called oitQwmeros; the small lump which forms in the spout is rolled into a ball and called cabezza; the dried strips pulled oat of the cuts is of very good quality and is called hola or hurucha. From Brazil is exported the famous Para india rubber. This is of very high quality, and is greatly esteemed by all manufacturers. No process can make a poor gum give a really good product. The system of gatliering it varies. Sometimes the tree is cut into by gashes from an axe, such gashes ex- tending in a row all around the trunk. Under each gash a small clay cup is luted fast with some fresh mixed clay. These collect from a tablespoonful of juice upward, which is collected, and the cups are removed on the same day. The next day a second row of cuts is made below the others, and the same AND THE MANIPULATION OF RUBBER. 21 process is repeated. This is continued until from a point as high as a man can reach, down to the ground the tree is full of cuts. Sometimes a gutter of clay is found partly around the trunk with crashes above it. In other cases a vine is secured Tree Tapped for India Rubber. around the tree and a collecting gutter is worked with it for a basis. « v, f The iuice is coagulated in a smoky fire. A dot- tomless jar is placed over the fire and some palm nuts are mixed with the fuel. The mould, which ,s often a canoe paddle, is smeared with clay to pre- vent adhesion and is then heated. A cup of ]uice is poured over it, and after the excess has dropped off it is moved about rapidly over the smoke and '22 nUBBER HAND STAMP MAKING hot air which ascends from the mouth of the jar. This series of operations is repeated until the coat- ing is quite thick; it may be as much as five inches. After solidifying over night it is cut open and the paddle or mould is removed. After a few days dry- Indian Drying and Smoking India Rubber. ing it is sent to market. With all the heating, during which it sweats profusely, it still retains fifteen per cent, of water. India rubber sap may be coagulated by an aqueous solution of alum. The process has been tried in Brazil, and is used to a considerable extent in AND THE MANIPULATION OF BUB BEE. 23 Pernambuco. It was proposed by an investigator named Strauss, and the process is still called by his name. One objection is that it gives a very wet product, and apparently one of inferior value to the smoked gum. The feeling that India rubber suffers in the gath- ering has been so much felt that it has been re- cently suggested that if possible the uncoagulated juice should be exported to Europe there to be worked up from the beginning. CHAPTER III. PROPERTIES OF UKVULCANIZED AND VULCANIZED IKDIA RUBBER. There are two broad divisions to which all varie- ties of india rubber can be assigned — nnvulcanized and vulcanized rubber. Speaking with a certain amount of license it may be said that more proper- ties characterize the former than the latter. The vulcanized article is very slightly affected by ordi- nary changes of temperature, cannot to any consid- erable extent be changed by heat short of absolute destruction or decomposition, cannot be united or moulded except in simple forms, is highly elastic, and is insoluble in almost every solvent for ordinary caoutchouc. Unvulcanized caoutchouc possesses very interest- ing and peculiar properties. The first part of the present chapter is devoted to this substance. Those who have never seen the crude gum as imported are familiar with the article almost pure in the form of sheet rubber and black rubber articles generally. These are of nearly pnre caoutchouc, though recently the tendency is to vulcanize them to a considerable degree. AND THE MANIPULATION OF RUBBER. 25 A piece . of pure gum containing no combined sulphur, iodine, or other vulcanizing constituent will be found to exhibit a very striking peculiarity. Two freshly cut surfaces when placed m contact will adhere. This is not in consequence of any viscous or sticky coating. When India rubber is cut the surface is perfectly dry and non-adherent except to itself. . The writer once had this property of adhesion brought strongly to his attention. In some analyt- ical investigations of coal gas he had proposed to use finely divided India rubber as an absorbent of sulphur. This constituent it absorbs from gas, and it seemed that a basis for a quantitative determina- tion of sulphur might be found in such property. Accordingly some raw India rubber was procured and with some trouble was cut up into little pieces which were put into a bottle. A day or two after- wards the pieces united wherever they were m con- tact, and an irregular cavernous lump was the result This involved no melting or softening or chano-e of shape. Each little piece was there intact and distinct but firmly attached to its neighbors^ The analogy of this action is seen m lead. Two fresh surfaces brought together, preferably with a twisting or wrenching pressure, adhere quite firmly. The adherence of India rubber and of lead each to itself is often exhibited by physical lecturers as an illustration of cohesion. The cohesion of mdia rubber is however far more perfect than that ot 26 RUBBER HAND STAMP MAKING lead^ probably because of its comi^aratively great resistance to oxidation, and because^ owing to its elasticity larger areas can be brought in contact. Comparatively great though this resistance to oxi- dation is, oxygen, especially in the allotropic modi- fication known as ozone, may act quite powerfully on the gum. Sunlight also can affect it injuri- ously. A more familiar illustration of the uniting of two pieces of the same material is seen in the welding of iron. The blacksmith heats two pieces of iron until they are nearly white hot and are pasty in consistency. On placing them in contact and ham- mering to force them together they unite so firmly as to be practically one. It is necessary that the surfaces of clean metal should be brought together. If the pressure induced by the hammering is insuf- ficient to bring this about, a flux is added which dissolves the oxide and causes the metal to come in contact with metal and to weld. The analogy with india rubber in its cohesive action is evident. Sur- faces long exposed or which are dusty do not cohere. The relegation of ice is similar in effect. The cohesion of india rubber is important and should be thoroughly appreciated. It is not saying too much to assert that the entire treatment of the raw gum depends upon this interesting property. The great lumps of gum are torn to pieces and washed free from gravel and dirt without going to powder, because owing to their elasticity they yield AND THE MANIPULATION OF BUBBER. 27 and as fast as torn apart the pieces tend to reunite. Again india rubber is mixed with pigments and vul- canizing reagents by a method practically one of grinding or masticating, but the material while it changes its shape, and by the admixture of the va- rious ingredients becomes less strong or easier torn, still remains intact, as it welds together or coheres as fast as disintegrated. As regards its chemical constitution the sap of a Para rubber tree has been analyzed with the follow- ing general results: (Faraday). Caoutchouc 80.70 Albuminous, extractive, and saline matter, etc 12.93 Water 56.37 100.00 Its specific gravity is 1.012. Caoutchouc itself or raw india rubber is a mixture of several hydrocarbons of the following composi- tion in general: Carbon. 87.5 Hydrogen 12.5 100.0 Its specific gravity is from .912 to .942. The hydrocarbons composing it are isomeric or polymeric with tur23entine. This fact brings it well within the range of familiar vegetable products. As will be seen the products of its distillation fall among the same polymers and isomers. 28 BUBBER HAND STAMP MAKING AVhen pure it is nearly colorless^ the dark color being due to impurities. In thin sheets it is almost or quite transparent. It burns readily, and with a very luminous, smoky flame, as might have been anticipated from its composition. The action of heat and cold on it is dependent on the degree of the temperature. At ordinary temperature it is elastic and firm. It can be stretched and will re- turn almost to its original size when released from tension. Yet the return to its shape is so liable to be incomplete, especially after long sustained stretching, that jDure unvulcanized India rubber is considered imperfectly elastic. Any elasticity it possesses is principally elasticity of shape as distinguished from elasticity of volume. In other words when pressed or stretched it may change shape to a great extent but hardly change its volume at all. A cube of 2^ inches under a weight of 200 tons lost 1-10 of its volume only. This is largely due to the fact that it represents an approximately solid body, or one destitute of consid- erable physical pores. Solids and liquids are very slightly compressible. Whatever degree of com- pressibility caoutchouc possesses is due principally to its minute pores. If the temperature is reduced to the freezing point of water a piece of raw india rubber becomes rigid and stiff. On application of heat it returns to its former pliable condition. The same return to flexibility may be brought about by stretching it ABB THE MANIPULATION OF RUBBER. 29 mechanically. This may be rather a fallacy. Stretching India rubber warms it, so that in tins mechanically imparted rise of temperature we may find at least a probable cause of the softening. If the temperature is raised several effects are produced, according to circumstances A piece which has been stretched and held stretched has its tension increased by a degree of heat considerably less than that of boiling water. Some oiler the theory that it contains air enclosed in its pores which, expanding, produces this effect. As the boiling point is reached the material softens and becomes somewhat plastic, so that it can be moulded into shape to a considerable extent and stretched to threads of great fineness. Its elasticity also disap- pears as the heat is maintained. These effects m- crease in extent up to a heat of 348 f S^''\^± The return to its original state .s not immediate liowover. Some time is required before the reduc- tion of temperature will have full effect. If now a still higher degree of heat is app led, •in^^tn^k^unani.ui.<).u..Ku' Masticating Machine. To prepare pure gum for the manufacture of sheet rubber and as a starting point for many other preparations, the india rubber is "^ masticated '' in AND THE MANIPULATION OF HUBBER. 89 special apparatus. The machine consists of a fixed cylinder within which is a corrugated roller set eccentrically and rotated by power. The perfectly dry sheets in the masticator are pressed and rolled and ground and produce a mass of even consistency. Here the welding or cohering action again appears in its fullest development. The perfect dryness of the mass enables it to keep reuniting as fast as divided. The action is assisted by the heat gener- ated, which is not inconsiderable. Sometimes the caoutchouc is warmed before introduction, and sometimes the roller is heated by passing steam through it. Masticating Machine. The masticating machine the French pictur- esquely term the wolf (loup) or devil {diable). It is given from sixty to one hundred turns a minute, and a machine large enough to treat fifty pounds of 40 BUBBEB HAND STAMP MAKING gum in a charge, requires five horse-power to drive it. In it the sheeted gum is ultimately brought to tlie state of a perfectly homogeneous dark brown translucent mass. The masticated rubber is peculiarly amenable to mechanical and chemical treatment. It can be shaped by heat and pressure, and it is the most soluble form and is used for making cement and solution, and is moulded into blocks for the manu- facture of sheet and thread rubber. In the process neutral body pigments, such as oxide of zinc, or sol- uble transparent ones, such as alkanine may be intro- duced; easily decomposed matter cannot be incorpo- rated on account of the heat. In all these machines S2:)ecial provision is made to prevent any oil from getting into the gum. There is no greater enemy to india rubber than oil or fats of any description. The flanges in the mas- ticator that roll just inside the bearing are for this purpose. Sheet rubber is made from the blocks of masti- cated gum by slicing. A machine is used for the purpose which carries a knife which works back and forth in the directioji of its length at high speed, making two thousand cuts a minute. The knife is kept wet by a stream of water, and about sixty cuts are made per inch. In many articles made from this sheet the marks of the cuts can be seen as a fine ribbing. The appearance is familiar to manv readers. AND THE MANIPULATION OF BUBBER, 4l The sheet is often cut from rectunguhir blocks, but cylindrical blocks are also used. The latter are rotated in front of the knife edge and a long, con- tinuous sheet can thus be obtained. The sheet rubber can be cut iiito threads on web- bing and braid. Ever3^one has noticed that these threads are usually square. The method of prepa- ration accounts for it. Vulcanized sheet is now almost universally used for threads. Round threads however can be made by forcing softened or partly dissolved gum through a die. It is from unvulcanized masticated sheet that toy balloons, tobacco pouches, etc., are made. It is the starting point for India rubber bands. For the usual form of the latter article the sheet is cemented into a long tube which is afterwards cut transversely, giving bands of any desired width. To make any of these articles satisfactory vulcanization is imper- ative. Unvulcanized rubber for many years was used, but it is "now completely displaced by the vulcanized product. Sheet rubber is made as above; is vulcanized by some of the absorption processes described in the chapter on vulcaniza-tion. We now come to the second product: regularly mixed and cured rubber. Its starting point is the washed India rubber from the washer and sheeter. We have seen that the ^^ure gum or caoutchouc is very sensitive to changes of temperature. At the freezing point of water it is hard and rigid, and at 42 RUBBER HAND STAMP MAKING the boiling point is like putty in consistency. There are several substances wliich can be made to combine with the gum and which remove from it this susceptibility to change of temperature. The process of effecting this combination is called vul- canization, and the product is called vulcanized india rubber. Sulphur is the agent most generally employed. In the factory the normal vulcanization is carried out in two steps, mixing and curing. The washed sheet india rubber which has not been masticated and which must be perfectly dry is the starting Making i^Iixed Ritbber. point, andtlie mixing rolls sliown in the cuts are the mechanism for carrying out the first step. These are a pair of powerful rollers which are geared so as to work like ordinary rolls, except that one revolves AND THE MANIPULATION OF RUBBER. 43 about three times as fast as the other. They are heated by steam, which is introduced inside of them. The sheet is first passed through them a few times to secure its softness, and then the opera- tive begins to sprinkle sulphur upon it as it enters the rolls. This is continued, the rubber passing and repassing until perfect incorporation is secured. About ten per cent, of sulphur is added, and a work- man can take care of thirty pounds at a time. This material is incompletely vulcanized. It is in its present condition very amenable to heat and is ready for any moulding process. Generally it is rolled out or ^^ calendered" into sheets of different thickness from which articles are made in moulds by curing. These sheets are of especial interest to the reader as they are the material from which most small arti- cles are made, including rubber stamps. This rolling of the mixed india rubber into sheets of definite thickness is done by special calendering rolls. The product is termed '' mixed sheet." In the mixing rolls the incorporation of other material is often brought about. Zinc white, lead sulphide, antimony sulphide, chalk, clay, talc, barium sulphate, plaster of paris, zinc sulphide, lead sulphate, white lead, oxides of lead, magnesia, silica, form a list of ordinary mixing ingredients. These lower the cost of the finished material and are often serious adulterants. For some cases the addi- tion if not carried too far is not injurious, or even 44 RUBBER HAND STAMP MAKING may be beneficial. A proper admixture renders the gum more easily moulded and treated in the shap- ing processes. Mixing Rolls. The next step in the vulcanizing process is the heating of the mass, which step is called ^'curing." Up to a temperature in the neighborhood of that of boiling water the mixed rubber can be heated with- out change except as it is softened. But if the heat is increased it begins to get a little more elastic and less doughy, and eventually becomes ^^ cured '^ or vulcanized. The temperature for vulcanization is about 284° F. (140° C). The word '' about " is used advisedly, for it is not only a question of heat but of time of exposure. After vulcanizing, including the curing, india rubber cannot be moulded to any great extent. In the manufacturing process, there- fore, it is before curing placed in the moulds. AND THE MANIPULATION OF RUBBER. 45 heated, shaped by pressure, and by exposure to a higher heat in a steam oven called a vulcanizer, is at once cured. To prevent adherence to the moulds they are dusted over with ground soapstone, and the rubber itself is often thus coated. The methods of vulcanization and curing, which may be of special use to the reader, are given in the chapters devoted to that subject (chapter XI.), and in the one devoted to rubber stamps. Hard rubber, termed ebonite when black, and vul- canite when of other colors, is simply vulcanized rubber contaiiiing a large percentage of sulphur added in the mixing process. The manufacture of coated tissues is effected in several ways. The following is a typical process. A mixture of one part washed and sheeted india rubber with one part zinc white, one fourth part sulphur, and about one third part naptha is mixed into a dough-like mass and is spread upon the cloth by machinery. The latter is simple. It consists of a bare board arranged to move under a scraping bar. The cloth is placed on the board and carried under the bar. The coating mixture is fed on one side of the bar upon the surface of the cloth. As it passes under, a regulated amount, according to the set of the bar, adheres. It is then dried by steam heat and recoated, until ordinarily six coats, each about one one-hundreth of an inch in thickness, have been given. Three coats are given in each direction with 46 RUBBER HAND STAMP MAKING. intermediate drying. The fabric is then cured by heat in vulcanizers. Sometimes the sulphur is omitted, from the mix- ture and cold curing, as described, later, is adopted. When the goods are made up the seams are secured with rubber cement, a thick solution of masticated gum. Such seams have to be vulcanized. Sometimes two such fabrics before curing or vul- canization, are placed face to face and allowed to adhere and are then cured or vulcanized. Enough has been said in this outline of the man- ufacturer's treatment of india rubber to show that the first treatment requires machinery. Very little can be done with mortar and pestle, although in making up solution these simple instrumentalities are available. As a starting point for making small articles masticated sheet rubber and mixed sheet rubber are the staple materials. The preceding steps are best accomplished in the factory. CHAPTER V. INDIA RUBBER STAMP MAKING. We have seen that India rubber cannot be cast in moulds. Except in special cases deposition from solution is not available. It has to be shaped by a combination of heat and pressure. When gently heated it softens and can be pressed in a mould. As it cools it retains the shape thus given and is moulded. This applies to all unvulcanized india rubber. If mixed rubber is moulded and heated to a higher temperature without removal from the mould the curing process is brought about and the rubber may be not only moulded but cured and the product is moulded vulcanized india rubber. The mixed sheet whose manufacture is described in chapter IV. (page 42) is the starting point in rub- ber stamp making. It is made for this purpose by the manufacturers. When the material is examined it looks like ordi- nary white india rubber, being firm in texture and quite strong. On heating to 280° F. to 290° F.^ (137° 0. to 143° C.) it begins to become ''cured/' and if in a thin sheet one to ten minutes are suffi- cient for the process. As the heat is applied the in- 48 RUBBER HAND STAMP MAKING dia rubber first softens and becomes much like putty. It can now be pressed through the smallest orifice and will fill np the finest details of anything it is pressed against. It is at this point that pressure must be applied to drive it into the interstices of the mould. As the heat continues it begins to lose its doughy or putty-like consistency. This marks the 'reaction of the vulcanizing materials. They gradually com- bine with and change the nature of the caoutchouc. The rubber while still quite soft is elastic. If pressed by the point of a knife it yields, but springs back to its shape when released from pressure. The india rubber is vulcanized. On removal from the mould it will be found to reproduce its smallest detail. The color and ap- pearance have not changed much, but its nature and properties are now those of vulcanized rubber. It is unaffected by heat or cold within ordinary ranges of temperature, and if the india rubber is of good quality and made by a proper formula it will last for years. The first thing to be described is the mould, which includes the arrangements for pressing the sheet of india rubber while heated. A small press is needed for this purpose. It may be of the sim- plest description, and as an example of a home- made but perfectly efficient one the illustration may be referred to. The base of the press is a piece of iron, if heat is to be directly employed. Where a AND THE MANIPULATION OF RUBBEB. 49 chamber vulcanizer is used both base and platen may be of wood. But from every point of view iron is the best. It lasts forever, admits of direct heat- ing, and does not split, warp, or char. Through two holes drilled near its opposite sides two or- dinary bolts are thrust. It is best to use flat headed bolts, and to countersink a recess for the Simple Vulcanizing Press for RrBBER Stamps. heads in order to keep the bottom level. Tlie beads may need to be filed off so as to reduce their thick- ness, in order to secure this object. The bolts may be soldered in place. One thing should be care- 50 RUBBER HAND STAMP MAKING fully watched for — the holts should be set true so as to rise vertically from the plane of the base. The platen is best made of iron, cut of the shape shown. This is an excellent disposition of the screw-bolt slots, as by swinging the right end of the platen back it can be taken off without removing the nuts and lifting it over the ends of the screws. Besides the two nuts fitting the thread of the screws it is well to have half a dozen extra ones larger than the others,, which will slip easily over the bolts, so as to act as washers. The object of these is to adapt the press to objects of different thickness. The thread upon an ordinary bolt does not extend clear to the head, but by slipping on some loose nuts the plates can be forced together if desired. This press can be simplified. Both base and platen can be made of wood, the platen being sim- ply bored for the bolts, and the latter driven tightly through the holes in the base so as to retain their place. Even this can be improved on as regards simplicity. Two blocks of wood screwed together by two or more long wood screws may be made to do efficient work. One trouble is apparent with all these devices, and that is the want of ^parallelism of the opposed planes. The base and platen may be true and parallel or they may not. Perhaps the simplest way of securing this is the best. It consists in placing across the base two distance pieces, which may be slips of wood. These must have perfectly AND THE MANIPULATION OF EUBBEli. 51 parallel faces. As the press is screwed up they will be gripped between the platen and base and will not only ensure their parallelism bnt will keep them at an exact distance apart. Such distance pieces are shown in the same cut. Pieces of printers' ^^ furniture/' spaces^ or ^^ quads/' may be used for this purpose. They should not be fastened in place if there is need to adapt the press to more than one thickness of material and matrix. The above described apparatus is a vulcanizing press. A further improvement in it may be effected by the use of spring pressure. Two strong spiral springs may be dropped over the bolts, the nuts being screwed on above them, or a powerful spring of flat brass or steel ribband bent into the shape of a shallow letter V may intervene between nuts and platen, the centre of the bend bearing against the centre of the platen. As regards the strength oi the springs there is this to be said. The distance pieces will prevent a spring that would ordinarily be too powerful from doing any harm. Such distance pieces should be used, as the springs must be based upon giving a pressure of many pounds per square inch of surface to be acted on. They should have a range of an eighth of an inch or more. The greater the range the more evenly will they work. The next cut shows an excellent little screw press, that is made for the purpose of pressing vulcanizing flasks. This is so simple that it will suggest to the 5'2 nUBBER HAND STAMP MAKING mechanical reader how he can make a single-screw press, which is by far the most convenient to use. In the stationery stores very small model cast iron copying presses designed for nse as paper weights are sold. They are excellent for a limited amount of small sized work. Vulcanizing Flask Clamp. A large sized gas heated press, such as made for the purpose of manufacturing rubber stamps, is shown in the next cut, p. 53. Its construction is obvious. It is termed by the trade a vulcanizer. Its manipulation will be given furtlier on. Type are generally the object to be copied. These are best set up with high quads and spaces. Naturally rather a large type is chosen, with extra wide spaces between the letters. Some advise rub- bing the type faces full of hard soap, afterwards brushing off the face, leaving the hollows filled. Sometimes wax is recommended for the same pur- AND THi£ MANIPULATION OF RUBBER. 53 pose. This prevents the plaster of the matrix en- tering so deeply into the cavities of the letters. The type forming the model to be reproduced, is locked in a frame. Two pieces of printers' furni- Gas-heated Stamp Vulcanizer. ture or other wooden strips screwed together by wood screws at their ends will answer for a locking frame for small inscriptions. The model to be copied need not be type, but any desired relief may be used, such as an electrotype, a stereotype, an engraving or another rubber stamp. In any case it is to be placed upon a flat surface, best an ^'imposing stone" or piece of marble, with 54 RUBBER HAND STAMP MAKING the inscription upwards. On each side of it dis- tance pieces reaching about one-eighth inch above its upper surface are to be placed. The next shaping appliance is the matrix or mould, or reverse of ^ the model which is to be copied. This in the case of rubber stamps is prop- erly called the matrix. Those who have witnessed the stereotyping of a large daily newspaper have seen the matrices of the type made of paper and paste, the whole mixture being termed ^' flong." Such a matrix is required for rubber type, but paper is rather too susceptible to heat although good work can be done with it. It also does not enter as deeply into the cavities of the type as is desirable. As a rule a fine quality of plaster of paris is to be recommended. What is sold as dental plaster is the best, but common plaster can be used. It is mixed with water or with a solution of gum arable or dextrine in water. For the latter enough gum should be added to make the mixing solution as thick as thin syrup. A piece of iron, perfectly flat and true, is now to be taken, large enough to more than cover the inscription to be copied. Upon its surface a putty made of the plaster and the liquid used in mixing is to be spread. This should be rather stiff. The surface of the iron should not be too smooth as it is desirable that the plaster should adhere well on setting. The plaster should be smoothly spread to a depth of three-sixteenths or a quarter of an inch. AND THE MANIPULATION OF RUBBER. 55 It is best applied with a palette knife or trowel, although a table knife will answer perfectly. If its surface does not become smooth it can be made so by applying a little of the solution with the knife or trowel. Before this has been done the model must be oiled. Olive oil or other clear oil is applied to all parts of the type faces, and the excess is then wiped off and cleared out of the interstices with a piece of blotting paper. Next the plate with the plaster is inverted and is pressed steadily down upon the model until it strikes the distance pieces. It is left to set. In about ten minutes it can be raised, when it will be found to give a beautiful impression true to the smallest detail of each letter. It has been said that water may be used as the mixing fluid. If this is done it is well to strengthen the mould by saturating it with an alcoholic solu- tion of shellac, after it has dried thoroughly, best for a few hours in an oven. This operates to strengthen the small projections that are liable to crumble or to break off in use. The dealers in rubber stamp supplies sell a lever press for conducting the operation of producing the matrix. The type is locked in a special chase, which is carried on a bed that travels under and out from under the platen of the press upon rollers. From each corner of the chase in which the type model is locked, a pin rises which is encircled by a CAi RUBBER HAND STAMP MAKING spiral spring. A square frame of flat iron with holes at the corners for the pins to pass through, rests upon these springs well above the type. The pins pass through holes in its corners. The matrix plate with its coating of plaster is placed upon this frame, which supports it above and not touching the type. The whole is now rolled under the press and the lever pulled to produce the im- pression. As the pressure is released the frame with the matrix is raised from the type by the action of the springs. This can be done immedi- ately, and before the plaster has set. It is almost impossible to raise it by hand with the requisite steadiness. The same chase with corner pins and springs can be used in a screw press, the one press answering for making the matrix and for moulding and curing the stamps. The plaster matrix can also be made by casting from a thinner mixture of plaster and water. After the type has been set up, or the model has been selected and placed face up and horizontal, a little ridge or projection must be made all around it. Paper can be pasted around it, and wound with thread for this purpose. It is oiled and wiped off as before. The plaster is now mixed Avith water to the consistency of cream, and is poured upon the model until it lies even with the projecting ledges or paper border. In an hour or less it can be removed. If water is used the mould should before use be treated with shellac solution as already described. The plaster may also be mixed AND THE MANIPULATION OF RUBBER. ^57 with gum arable solution, or with three to ten per cent, of powdered marshmallow root. This in- creases Its toughness. What is known as the oxychloride of zinc cement appears to the author to be far preferable to com- mon plaster of paris. It is a trifle more expensive, but it costs so little that it is well worth trying. It is made by mixing oxide of zinc with a solution of zinc chloride. No particular strength of solution or proportions are prescribed; the zinc chloride solu- tion should be a strong one, and the mixture should be of about the consistency of soft putty. Zinc chloride may be bought as a solid substance or in strong solution. The latter answers for the mixing directly. It may also be simply made by dissolving metallic zinc in strong hydrochloric acid. The manipulation is exactly the same as with plaster of paris. The manufacture of papier mache and of other matrices is given in a special chapter. For all ordi- nary purposes the plaster or cement matrices are ample. The stamp is made from tlie mixed uncured sheet rubber, whose preparation in the factory, including the operation of calendering it into sheets, has already been described. The best advice the reader can be given is not to attempt to make it except as a matter of interest and experiment. It can be purchased especially prepared for stamps from the dealers in India rubber. 58 nUBBER HAND STAMP MAKING A piece is cut from the sheet large enough to cover the face of the matrix. It shouki have a perfectly smooth surface, without cloth wrapper marks sometimes found impressed on it. The sheet as received from the maker is about one-eighth of an inch thick. It is thrown into a box of powdered soapstone or talc to secure a coating of the same on both sides. A little is dusted over the matrix and the excess is blown off. The matrix is now placed upon the base of the press, and heat is applied. To carry out the process most simply the press if of metal may be placed upon a support over a gas burner or kerosene lamp, or even on a kitchen range or stove. It will in a few minutes become warm. The sheet of india rubber is now dusted off and is placed in the press upon the matrix. The platen of the press is screwed down upon it. As the india rubber becomes hot it begins to soften and flow. By the action of the screw of the press it must be forced down from time to time as it softens. This drives the putty-like material into all the interstices of the mould. The excess escapes from the sides of the tympan in cases where the latter is of restricted area. The press theoretically should be heated to the vulcanizing temperature, which is 284° F. (140^ C). In practice the heat is not determined with a thermometer. The operator learns by experience how much heat to apply. The regulation type of gas heated press or stamp vulcan- izer is shown in the illustration on page 53. AND THE MANIPULATION OF RUBBER. 59 As some of the India rubber is sure to protrude, the progress of the work can be watched from its action. By pressing the point of a knife against it the period of vulcanization can be told. Before the material is heated it is elastic and resists the Oil Stove for Heating Vulcanizers. pressure of the knife; as heat is applied it beco^ies soft like putty; as the "heat increases it again stiffens and becomes quite elastic. At this point the press can be opened and the sheet and matrix can be taken out or the platen swung aside. On pulling or stripping the sheet from the matrix it will be found to reproduce the model in elastic India rubber to the minutest detail. As regards the minor details there is something 60 RUBBER HAND STAMP MAKING to be said. Distance pieces to gauge the thickness have been recommended for the home-made press^, page 48. Care must be taken to have these low enough to provide for enough excess of material to produce a good impression. For ordinary stamp work they should allow about one-sixteenth of an inch for the '' squeeze. ^^ It will be seen that by using the distance or gauge pieces both for making the matrix and for moulding and cnring the stamp, abso- lute parallelism of surfaces will be secured. The reader will have noticed in the description and will find at once in practice that the press has to be screwed up as the rubber softens. Where heavy iron presses are used the large mass of heated iron comprised in the platen of the press instantly heats the upper surface of the india rubber sheet and the heat immediately penetrates into it, while the heated matrix heats it from below. Thus it softens at once, and the press is directly turned down and the india rubber is driven into the mould and curing at once begins. But where small presses are used this manipulation is not so easy. For such the springs mentioned on page 51, are highly to be recommended. The matrix and india rubber can be put into the cold press, and the tympan with intervening springs can be screwed down so as to compress them. Then on .applying heat the mould- ing takes place automatically. With a hot press and good sheet a period of three to ten minutes is ample for moulding and curing. AND THE MANIPULATION OF RUBBER. 61 Instead of sprinkling with talc the matrix may be oiled and sprinkled with plumbago and afterwards polished with a brush. This is not so clean a ma- terial as talc and is not to be recommended for general use, especially as oil is a bad substance to bring in contact with rubber. The distance or gauge pieces whose use has been recommended are not necessary where presses work- ing truly parallel as regards their opposing faces are used. But where home-made apparatus is used they will be found a valuable addition. In describing the simple press it was said that it could be made of wood. It is evident that a wooden press could not be used for direct heating. Such a press must be used in a hot chamber or vulcanizer, properly so called. Originally rubber stamps were generally made in chamber vulcanizers. The next cut shows a combined matrix making, moulding and vulcanizing apparatus of very conven- ient and compact form and adapted for rapid work. As the press stands in the cut the matrix press is seen in front. A box or chase is carried under its platen by two trunnions, so as to be free to oscillate to a limited extent. The type model is secured m this box. Above this box or chase is a cross-bar with screw and platen attached, connected at will to two standards or pillars, so as to constitute the matrix press. A matrix plate swings on a hinge joint between the two presses. The hinge-pin is removable. Its i 62 RUBBER HAND STAMP MAKING ends can be seen projecting to right and left of the press columns. The hinge is at such a height that when the matrix plate is swung forward over tlie type box it will rest upon it in a nearly horizontal position. The pivoted box will adjust itself so as to come into parallelism with the plate. Matrix Making, Moulding and Vulcanizing Apparatus. "When the matrix plate is swung back it falls upon the base plate of the vulcanizing press seen in the rear. In use the composition used for the matrix is spread upon the matrix plate, which may for this AND TEE MANIPULATION OF BUBBEB. 63 purpose be removed from the apparatus It is replaced and the hinge-pin is pushed home. Th s i/done with the composition coated side facing tl« front of the apparatus as it stands m the cut. The plate is then swung forwards, the platen of the £ rix press being turned forward out o£ the way, and is pressed down upon the type or other model that ;Xin the type box. If desired tbo P-sms .^^^^^^^^ to force it home. The cross-bars of both the pi esses are arranged to swing each one on one of the pillars, so that the platens are turned to one side out of the way of the matrix plate as it is swung back '"ar'pressure is released and the platens are tnrned aside The matrix plate is swung over to the ta upon the bed-plate of the vulcanizing press. Heie it lies with the composition-matrix "'TMghted lamp, either alcohol or gas, is placed beneath the bed-plate of the vulcanizing press on which the matrix rests. This qnickly dries it and brings it to a good curing temperature The cioss bar and platen may be swung over it during the heatincr so as to be heated at the same time The mSis talced when dry and hot; ^^^^ itself talced, is placed upon he matrix he p aten is screwed down upon it, and m a minute oi two the moulding and curing is completed A vulcanizer, properly speaking, is a vessel ar ranged to heat to a definite degree any desired a,t,- 64 RUBBER HAND STAMP MAKING Rubber Stamp Vulcanizeb. cles which are to be cured. The favorite type have been the steam vulcanizers. If steam is generated from water at a constant pressure, other things AND THE MANIPULATION OF RUBBER. 65 being equal a constant temperature will be pro- duced. By raising or lowering the pressure the temperature can be made to rise or fall. A steam vulcanizer is a tightly sealed vessel which contains water and which is provided with a thermometer oi- a pressure gauge as well as a safety-valve, safety disc or safety plug. By keeping the gauge at con- stant pressure or by keeping the thermometer con- stant the temperature can be limited and kept steady. The following table gives some pressure in pounds per square inch with temperatures corre- sponding to steam of such pressures: Lbs. per square inch. Temp. Fahr. Temp. Cent. 45.512 275° 135° 52.548 284° 140° 60.442 293° 145° 67.408 300.2° 149° The illustration, p. 64, shows a vulcanizer of modern type made for rubber stamp work. In some recent vulcanizers the water and steam are excluded from the vulcanizing chamber, being contained within double walls forming a steam jacket and maintain- ing a constant heat within the chamber. These illustrate a point that has been mnch misappre- hended, namely that curing is independent of pres- sure or atmosphere. Because vulcanizers have generally been filled witli steam at high pressure many have supposed that the steam or pressure had something to do with their action. The fact is that 66 RUBBER HAND STAMP MAKING it is only the heat due to the steam at such pressure that is instrumental. Steam is a very powerful radiator and absorber of so called radiant heat. For this reason an atmosphere of steam maintains all Steam Jacket Vulcanizer. parts of the vulcanizer at an even temperature and is to that extent advantageous. Its presence and the pressure it generates are not by any means re- quired for vulcanizing. Its pressure is entirely without effect. To use a steam vulcanizer, water is introduced. AND THt: MANIPULATION OF RUBBER. 67 the article m the press or mould is placed in it, and the top is secured. Heat is then applied, best if on the small scale, from a Bunsen gas burner gas, or oil stove. Either the pressure gauge or thermometer may be watched, and the flame turned up or down to keep it at the proper temperature. Moulding caimot be executed in the ordinary closed chambers. The press must first be heated to the temperature of boiling water or thereabouts and the moulding is then effected by screwing down the mould screw, upon the sheet and matrix. It is then placed in the vulcanizer and cured. The manufacturers supply gas regulators which automatically regulate the gas supply. These are worked by the steam pressure. If any one wishes to study the practical manipulation of small steam vulcanizers he can see them in use at any dentist's office. There is no need of a steam vulcanizer for ordi- nary stamp work. The hot press system already de- scribed answers every purpose and is in use by the most advanced manufacturers for thin sheet work. But if a wooden moulding press is used then it must be heated in a vulcanizer or some kind of oven or hot chamber. A very simple and reasonably satisfactory oven or air bath can be made from a flower pot and a couple of tin plates. A plate larger in diameter than the mouth of the flower pot forms the base of tho ap- paratus. This is supported on a stand over the gas es RUBBEB BAND STAMP MAKING lamp or other source of heat. A smokeless flame or one depositing no lampblack should be used. Alco- hol or a kerosene oil stove illustrated on page 59 are excellent. On this plate a smaller plate is inverted, which latter must be so small as to be surrounded by the flower pot and to be included within it when the pot is placed over it like an extinguisher. Flower Pot Vulcanizer on Stand. A chemical or round stemmed thermometer is arranged to go through the aperture in the up- turned bottom of the pot. This may be hung from a sup23ort or it may be secured by passing through a hole in a cork or block of wood. Its bulb should AND THE MANIPULATION OF RUBBER. 69 be near the part of the chamber to be occupied by the mould or press. The press with the article to be cured is placed upon the inner plate. The temperature is main- tained at the proper point by regulating the heat, and all the conditions for excellent work are sup- plied. The disposition of the apparatus is shown in the cuts. iNlKKIoft OF FLOWtH PoT VULCANIZER. Another arrangement equally simple is given in the next cut. An iroli kettle has a layer of type metal or lead poured an inch thick cast within it upon its bottom. A thermometer passing through a hole in the cover enters a cup of glycerine that stands upon the bottom. This gives the tempera- ture. The object of having a thick or a double bottom is to prevent excessive radiation of heat from any one part. The essential condition for good opera- 70 nUBBEU HAND STAMP MAKING tion is to maintain an even temperature throughout the chamber. Fish Kettle Vulcanizer. The thermometer is not an absolute necessity. By removing the press from time to time and in- specting the overflow of india rubber the progress of the operation can be watched. An extra piece of india rubber may be placed on a piece of wood by the side of or upon the wooden portion of the press, and its condition can be taken as the crite- rion. Pressure with tlie point of a knife will tell the vulcanizing point. By the press system of curing, a heat far above the vulcanizing temperature may be made to do good work by a very short application. There is AND THE MANiPJJLATION OF BUBBEtt. 71 however danger of burning the work if left in too long. If the air-bath with thermometer or the steam vulcanizer is used, and the heat is kept down to the proper curing temperature, there is no danger of burning the india rubber even if the curing is considerably prolonged. As the flower pot has often to be lifted off for introduction or removal of the press, and as it gets quite hot, a holder of some kind is requisite. A piece of heavy blotting paper is very convenient for this purpose. The flower pot system with thermometer can be further simplified by being used on a stove or range. A china saucer inverted, or some similar support, should be placed under the pot. A part of the stove at very low heat will suffice. The kettle vul- canizer, can also be placed on a stove so as to dis- pense with gas or oil. Finally^ as the last step in simplifying the work, a stamp can be made without any special apparatus beyond a hot flat iron. The matrix may be placed on a stove where the heat is rather low, the talc- coated mixed rubber sheet placed upon it, and on this a hot flat iron. In a few minutes if the heat is sufficient the stamp will be finished. A few words may be said about the type. High spaces and quads between the letters should be used, such as will come up to the shoulder of the type, as has been said. But a very nice effect is produced by using low quads between words. This leaves 72 RUBBER HAND STAMP MAKING. each word elevated by itself, producing a good appearance. Autograph stamps are made from a model cut in wood by a wood engraver. The autograph is writ- ten in some form of copying ink upon a piece of paper, and is transferred by moistening and. pres- sure to a block of wood. With an engraver^s tool the wood is cut away from the lines, as the block is routed after the inscription has been ^^ outlined.^* The woodcut is used as a model for making a matrix. It is evident that an autograph of fair quality could be obtained from a chalk plate. But in rub- ber stamp work to get good results certain essential parts should be of the best. These parts include the mixed rubber, model and matrix. A departure from excellence in any of these tends to the produc- tion of an inferior stamp. What is known as a "healthy cure" is above all essential to the appear- ance of the product. The stamp thus made is attached to a wooden handle by common glue or by one of the rubber cements given in chapter XVI. CHAPTER VI. IKDIA RUBBER TYPE MAKIKG. India rubber type are often used to set up differ- ent inscriptions in wooden handles, or different date figures in rubber stamps. The hitter are in such cases made with slots or recesses to receive them. Rubber type are much shorter than regular type, and as a rule are larger in the body in proportion to the face of the letter. Where only a few are re- quired the following process is the simplest way of making them from mixed rubber sheet. The type which are to be copied are set up on a level base or imposing stone, and quads or spaces are put between them. High quads and spaces should be used; otherw^ise they should be pushed up until even with the shoulders of the type. After oiling the faces a matrix is produced exactly as described for stamps. Before it has set quite hard the plaster or cement is cut oft so that it will just fit within a little ''flask" or frame. The latter may be made of tin or wood and may be rectangular or circular, provided it is large enough to include within its area the full working face of the matrix. It should be about half an inch ^irpm^ js AND THE MANIPULATION OF RUBBEB. 7o goes down to its seat without expelling any india rubber more of the latter is required and is accord- ingly inserted, the plunger being taken off for the purpose. The softened gum should ooze out around the sides of the plunger. The whole is again put under pressure, and the platen is screwed down, and if all is right an excess of rubber showing itself, the whole is put in the hot chamber, the heat is raised to 284° F. (140° C), and is maintained there for half an hour. It is almost a necessity to secure the matrix plate to the bottom of the flask. This for a single opera- tion may be done by screws, or ior several operations by hooks or catches. When the curing is complete the mould is re- moved from the vulcanizer, is allowed to cool and is opened. The block of type will come out witli per- fect reproduction of the letters upon one side. If all the directions have been followed as regards dis- tance pieces, level imposing surface, etc., both faces will be exactly parallel, and any number of other blocks can be reproduced of exactly the same height, not necessarily from the same matrix, although one good matrix can be used many times. The type have now to be cut apart. This is done with a sharp knife which is kept wet. It is worked with a sawing motion, and if sharp and properly used will cut with regularity, and smoothly. T^^pe with knife marks on the sides are always unmechan- ical in appearance and seem to be " home made.^" 76 RUBBER HAND STAMP MAKING. The object of using high quads and spaces or of pushing them up, will now be evident. It secures the evenness of the general face of the block of letters, which otherwise would have a deep depres- sion between each pair of letters. If the quads and leads are properly arranged, the letters will project upwards from a smooth, plane surface. The dealers in rubber stamp maker's supplies sell special steel moulds for the purpose of making them. This does away with all necessity for making matrices, and making up a flask, etc. The general manipulation is that given above. Where many are to be made the regular mould is by all means to be recommended. Sometimes type ;ire made by cementing single letters made by the stamp process upon wooden bodies. CHAPTER VII. THE MAKING OF STAMPS AND TYPE FROM VULCAN- IZED INDIA RUBBER. Although all reference hitherto in the matters of stamps and type has been to their manufacture from uncured india rubber, a good deal can be done with vulcanized and cured" gum. The stock that is known in the trade as pure gum, such as is used lor bicycle tyres, for steam packing and the like, can be made to yield to moulding to a certain degree. It will not flow and unite as will the uncured gum, but it is evident that in certain cases its stiffness is even an advantage. Thus with it, rubber type can be made without any flask or frame. The material has stiffness enough to support itself. ^ The manipulation is of the simplest. A piece is cut out with a knife so as to be of proper thickness and size. It should be a little thicker than will ultimately be required. The two opposite surfaces should be smooth and parallel. It is talced, and placed in the press with the matrix beneath it, and subiected to pressure by the screws being turned down. It is then placed in the vulcanizing chamber and heated to about ^84 F. (140 C). 78 RUBBER HAND STAMP MAKING After it has become hot it softens a little. The press is removed from the hot chamber and is again screwed down as hard as the matrix can stand. This point is largely a matter of judgment. The heat is largely indifferent as long as it is anywhere near the above temperature. By one or two repetitions of the pressing and heating the softened India rubber can be made to take quite a deep impression from a suitable matrix. It is allowed to cool under full pressure. When removed from the press, it will retain the characters. It is evident that impressions in as high relief or as deep and clear as those yielded by uncured india rubber need not be expected. But where the other cannot be had, or where some experimental or tem- porary work only is on hand, this process will be very convenient. The material may be half an inch thick. From such india rubber type can be cut with advantage. Old rubber can be thus used. The writer has ob- tained excellent results from pieces of an old dis- carded bicycle tyre. The great point is to apply a heavy pressure to the hot material. Many other articles can be thus produced extemporaneously. At the same time it must be considered only a makeshift. One who has used the soft, easy flowing uncured gum would never be reconciled to the use of so rigid and diffi- cultly moulded a material, one too that can never be trusted to reproduce intricate moulds of consid- AND THE MANIPULATION OF RUBBER. 79 erable depth. In the slow yielding of the half melted uncured gum, so amenable to slight pressure, a quality of availability is found that is missed in the other. One is worked by main force where the other readily yields and takes the most complicated shapes. By the above process stamps of such thickness may be made that they can be used without handles. It is also useful for impressing a designation of any kind upon ready cured articles. It suggests a very useful department of manipulation of India rubber. The heating and moulding can be done also in a hot liquid bath such as described in chapter XI. I CHAPTER VIII. VARIOUS TYPE MATRICES FOR RUBBER STAMPS AND TYPES. Matrices for stamp moulds can be made by sev- eral of the methods used by stereotypers. Thus an electrotype could be taken directly from the face of the type. There would be little or no utility in doing this where the simpler processes are available. papier mache matrices. The stereotyper for daily newspaper work uses very generally the papier mache or " tiong " process of reproducing the page. This is also available for rubber stamp making. The first requirement is paste. This is made by softening twelve parts of whiting in forty parts of water, letting it soak for an hour or more. Nine parts of Avheat flour are added. This is best mixed with a little water before adding to the main mix- ture. It is then brought to the boil and seven parts of glue softened by soaking in twenty-one parts of water, are added. For each gallon of such mixture, one ounce of wliite crystallized carbolic acid is added if it is to be kept for a long time. AND THE MANIPULATION OF RUBBER. 81 The ^^ flong " is made by pasting together, one on top of the other, a sheet of fine hard tissue paper, three sheets of blotting paper (about 23 pounds to the ream), and a heavy sheet of manilla paper. The pasting must be smooth and each layer must be pressed and rubbed down, but not too hard. It is very important to secure perfect smoothness and regularity, and entire absence of air bubbles. Every printing office where the process is used has its own traditions as to the preparation of flong. As a. great deal depends on manipulation, it would be well to endeavor to inspect its practical use in a newspaper printing office before making it. Keady prepared flong can also be procured. The form of type must be very clean and there must be no paste on the tissue paper face of the flong. The type are lightly oiled, some powdered talc is dusted over the damp tissue paper face of the flong, and the mass is laid face downward on the type. With a stiff haired brush the paper is now beaten down against the type. Great care must be taken to beat vertically; a slight side action will ruin the resulting matrix. If the brown paper will not stand the beating, a cloth may be spread over it. The progress of the work can be watched by rais- ing up a corner from time to time. When suffi- ciently deep the last touch is given by the printer's planer. This is a block of hard wood. It is placed 82 BUBBER HAND STAMP MAKING upon the back of the flong and is hammered down. The operation is repeated until the entire area has been treated. For much rubber stamp work the area wouhl be so restricted that shifting would be unnecessary. The work is then put into a heated screw press, such -as the vulcanizing and matrix press, and is dried for a period varying from some minutes up to half an hour. Some blotting paper is advanta- geously pressed on top of the whole in the press while drying. The press is opened, the flong re- moved, and dried in an oven. It is kept under a piece of wire net while drying to keep it flat. The net may be of wire, .064 inch thick, with six meshes to the inch. This baking is not strictly necessary for rubber stamp work. This gives a matrix which may be used as rub- ber stamp moulds. In use it is recomended to place a piece of smooth tin foil over it. This tends to give a smoother surface to the rubber. STRUCK UP MATRICES. Didot^s polytype process may be advantageously used for producing type metal matrices. The fol- lowing is the method of applying it. The type form is firmly locked and is backed up by and secured to a solid block of wood. It is sus- pended in a sort of gallows frame with the face of the type downward and exactly level a few inches above a table, Underneath it a shall oav tray is AND THE MANIPULATION OF RUBBER. 83 placed, into which soiiTe melted type metal is poured The melted metal is carefully watched. The block and type are held by a catch so as to be released at will. Just as the type metal is ori the point of solidifying, the block is released and drops upon the metal in the tray. The type should be slthtly oiled. The force of the blow produces a matrix in the metal, and the form can at once be removed. ^ . ^ ^ , . , It is well to have accurately adjusted distance pieces for corresponding striking pieces on thetype block to impinge npon. The process is highly spoken of, especially for small forms such as those mostly required for rubber stamps. CHALK PLATES. The base for this form of matrix is a metal plate whose surface is slightly roughened with sand- paper. It is next rubbed over with white of egg, and flooded with the chalk wash made as follows: Flong paste (described under Papier Mache Ma- trices, page 80), six ounces; whiting, twenty-four ounces; water, three pints. The whiting is softened by soaking for an hour or more. The whole must be intimately mixed. It should cover the plate to tlie depth of one-thirtieth to one-twentieth of an inch. The plate is dried in a perfectly horizontal position. . . , When dry the design or writing, etc., is made with a smooth steel point, the lines being earned 84 nXJBBEK HAND STAMP MAKING. clear throiio-h the wliite Taver to the metal. The mould is now baked at a temperature well above boiling water; as high as 392° F. (200° C.) may be reached without harm. If the coating seems too tliiu, an extra coat can be given between the lines especially over the larger areas. This must be done before the baking. A pipette may be used for putting on this coat. This deepening has the bad effect of increasing the chance of the coating stripping from the metal. The matrix thus prepared is used in the press just as is the ordinary plaster matrix. It is suited for reproduction of autographs, scrip, diagrams, etc. I I CHAPTER IX. THE MAKIKG OF VARIOUS SMALL ARTICLES OF INDIA RUBBER. India rubber can be so readily shaped in moulds and the latter are so readily made of plaster of paris that any one who is interested in such things will find endless amusement in working out different designs. Before suggesting any specific articles the following are the general points to be kept iu mind. The material may be uncured mixed sheet of any thickness. As we have seen this material when heated and pressed runs together. It can be forced into any shape by comparatively slight pressure. So exactly does it reproduce the smallest line or mark, that care must be taken to have the moulds very smooth and free from defect. Powdered soap- stone is used to prevent adherence to the mould, but great care must be taken not to mix it among the pieces of the india rubber, where several are used in one article, as it will prevent their coalescing or running together. Another point is to contrive to introduce the proper quantity of rubber. The aim must be to 86 RUBBER HAND STAMP 31 A KING have a slight excess, but to avoid waste this should be as little as possible. Unless some rubber is squeezed out there is no certainty tliat the mould has been filled. Any projecting ''fins" from the overflow are cut o2 with a knife or scissors after the article is removed from the mould. Plaster of paris or dental plaster mixed with dex- trine or gum arable water or the zinc oxychloride cement, already described, is to be recommended for the moulds. They should be made, if deep, in frames or " flasks " of tin, as plaster if unsupported is liable to split open when the rubber is forced home. For many articles the hot press can be used. Such articles are mats and other thin flat pieces. The rubber stamp sheet is a good material for them. For thicker articles a thicker sheet can be used, and sheet of any gauge can be procured from the maker. Much of what has been said about India rubber type applies to the making of miscellaneous shapes. It will also be understood where wooden moulds are spoken of that plaster, or, still better, metal can be substituted, and is to be recommended for nice work as the grain of the wood is very apt to show where the India rubber comes in contact with it. Suction discs and similar small articles into which an extra thickness of India rubber enters are best cured in a vulcanizer. The flower pot arrangement is excellent for such. The time for curing may be somewhat extended on account of the greater thickness of material to be acted on. AND THE MANIPULATION OF RUBBER. 87 Suction Discs.-Fov suction discs a n'o^jd js required wliicli will produce a shallow cup wi h the dge feathered or reduced to a very slight thickness. Its outer surface should be raised in tlie centre so as to give a projection for attachment ot the hook The discs are generally made small, not over an mch in diameter, as they are not reliable for any hea y service Their principal use is to suspend ad^ertls- :; cards and light articles to the glass of show windows. The following is a method of making a simple mould. , i-i i, A hole to give the outside contour should be bored in a small piece of wood. A marble which will exactly fit the hole is next required. Some Blaster of paris is mixed with water and put into the bottom of a.e hole, and the oiled marble is pressed down until the plaster rises and fills the entire space u^der the marble. After it has set the marble i removed. The proportions should be so arranged hat Ihe plaster will have risen at the sides withm an eighth of an inch of the surface of the wood. Th' gives the exterior mould. For the cup or Sow a marble a shade too large to enter the '^tnnrV::tssary two thicknesses of mixed sheet rubber cut into disc shape so as to fat the h i: are inserted in the block, and the Wg- «ai^^ is placed on top and sci^wed down by the pie s^ TTpnt is now applied in the vulcanizer. When the Ueat IS now app .^^^^^ ^ thermometer indicates ai^^ C.) to 250° F. (121° 0.) and on evap- oration should leave no more than ten per cent, of residue at 320° F. (160° C.) Payen recommends a mixture of 95 parts bisulph- ide of carbon with 5 parts of absolute alcohol. Commercial chloroform is apt to be too impure to act as a good solvent. It is apt to contain alcohol mixed with it as a preservative, which impairs its effectiveness. Some of these solutions are better suited than others for the deposition of thin layers by evapora- tion. Turpentine gives a very sticky and unman- ageable solution, which dries very slowly. Payen's solution and the chloroform and the benzole solu- tions may be cited as especially adapted for this purpose. Careful vulcanization by the cold curing method can be applied to articles made by such deposition from evaporation. In the case of all of them some form of mastication for tlie India rubber is needed. The simple mortar grinding of the gum swelled by the solvent is the only practical treatment without special apparatus. When it is remembered that fixed oils are de- stroyers of vulcanized or unvulcanized india rubber it will be obvious how important it is to use pure solvents. Too great care cannot be taken to pre- serve the liquids pure and free from such matter. A solid hydrocarbon may be used. Thus paraffin wax, such as candles are made of, when melted acts 106 RUBBER HAND STAMP MAKING as a solvent. The resulting liquid solidifies when it cools, retaining an almost greasy feel. Boiling oil of turpentine is recommended "by some for the solution of vulcanized India rubber. Phenyle sulphide, it is stated, will soften it so as to render it workable. The latter discovery is credited to Dr. Stenhouse. It is stated that a solution or pasty mixture of one part of caoutchouc in eleven parts of tui-pentine with one half part of a hot concentrated solution of sulphur (potassium sulphide) gives on evaporation a film neither tacky nor soft, a species of vulcaniza- tion taking place. It is of much interest to note that an aqueous solution of india rubber has been proposed in which the vehicle is a solution of borax in water. This is well known to be a solvent for shellac and other resins. It has been recommended often as a vehicle for rubbing up india ink. The ink made by mixing lampblack with the shellac solution is nearly water- proof. A shellac varnish is given by the plain solu- tion. The experiments upon india rubber were pub- lished in a recent trade paper. One method of making the solution is as follows. A solution of borax two fifths saturated is made by adding to two volumes of saturated solution three volumes of water. To this is added a solution of india rubber in benzole or other hydrocarbon of such strength and in such quantity as to contain AND THE MANIPULATION OF RUBBER. 107 from three and one-half to four and one-half per cent, of India rubber referred to the borax solution. It is now vigorously shaken and heated to 120°-140° F. (49°-60° 0.) and the agitation, not too violent, is continued until it cools. Ceara or Madagascar rub- ber answers best; Para is not so good for this for- mula. This may be termed the indirect or emul- sion method. For direct solution from two to three volumes of water may be added to three volumes of saturated borax solution. The India rubber is added in ex- tremely thin shavings and the solution is heated. For weak solutions the boiling point need not be reached. For strong solutions the heating should be done under pressure so as to bring up the pres- sure to one to three atmospheres. Such solutions may contain as much as eight per cent, of the gum. The mixture is liable to coagu- late or gelatinize just at the wrong time, but it may be of value as a vehicle or as a waterproofing agent. It deserves further investigation, which it is to be hoped it will duly receive. Great care is necessary in working with naptha, benzole, carbon disulphide and similar liquids. Their vapor is given off at ordinary temperatures and may travel some distance to a lamp or fire and become ignited and carry the flame back to the ves- sel. Their vapors are also anaesthetic and should be avoided as regards inhalation. CHAPTER XIII. EBONITE, VULCANITE AND GUTTA-PERCHA. Ebonite and Vulcanite. — These two well known substances are India rubber, in which the vulcaniza- tion process has been intensified. From twenty- five to fifty per cent, of sulphur is added in the mixing, and the curing is prolonged to several hours. A temperature of 275° F. (135° C.) for six to ten hours is sometimes recommended, but gener- ally a shorter period at the regular temperature, 284° F. (140° C), may be employed. The mixed sheet is made and sold extensively for dentists^ use. It is soft and flexible and very easily moulded. It is treated like the regular mixed sheet in every respect, except that plumbago brushed on the slightly oiled surface of the mould is recom- mended instead of the light colored talc, to prevent adherence. Wax where available is better than oil. Sometimes specimens are built up in sections. About an hour before full vulcanization in the fourth stage, new material can be added and will attach itself to the old. The stages of vulcaniza- tion are thus given by Bolas. AND THE MANIPULATION OF RUBBER. 109 ** Several distinct stages or steps may be traced during the curing of ebonite; and I wish to call your attention to some specimens illustrating these various stages. **Here, in the first place, is the plain mixture of sulphur and rubber, this being nearly white, and capable of becoming quite plastic or soft by the ap- plication of a gentle heat. '^ The second specimen illustrates the action of a very moderate degree of heat on the mixed material, this particular sample having been heated to 128° Centigrade for twenty minutes. It is, as you see, somewhat darkened, and has lost a little of its orig- inal softness; while a degree of heat which would have rendered the original mixture plastic, like putty, fails to make much impression upon it. '' The third specimen illustrates the effect of a more prolonged heating, this sample having been heated for an hour to 135° Centigrade. It is olive green in color, and has acquired a certain amount of elasticity, resembling that of a rather inferior quality of vulcanized caoutchouc. '' The fourth stage of curing is illustrated by this specimen, which you see is brown, and tolerably hard. Ebonite in this state refuses altogether to become plastic by heat, and a temperature of 150° maintained for half an hour or less would suffice to bring it to the fifth stage, or that of finished ebonite. *' The fifth stage, or that of properly cured 110 RUBBER HAND STAMP MAKING ebonite, is the goal to be arrived at in manufactur- ing the material. There should be no places where the curing is imperfect, a kind of defect which is likely to hap|)en when articles of unusual thickness are vulcanized, and no portion of the ebonite should be spongy or honeycombed by air bubbles. '^ The sixth, or spongy state, is generally the result of over-heating, bubbles of gas forming in the material, and converting it into a kind of porous, cinder-like mass. ^^A specimen will now be handed round, which illustrates the third, fourth, fifth and sixth stages, as already described. The specimen in question was cured on a hot plate, this liaving probably been heated to 160° or 170° Centigrade; and you will be able to trace all gradations in the curing operation, from the first setting of the plastic material to the destruction of the ebonite by overheating." Cement for uniting pieces of the partially cured material may be made by rubbing up some of the untreated scrap with benzole. At the heat of boiling water, ebonite can be bent to a certain extent, which bend it retains on cooling. When warm an impression of a coin or relief die may be made on it by heavy pressure which it will retain. On heating the image disappears. If before heating the surface is planed off and the piece is heated the image formerly in intaglio will expand into relief. By the exact process of rubber stamp making AND THE MAN IP ULA TION OF B UB BEB. Ill excellent stereotype plates may be made of eb- onite. It can be turned at high speed in a lathe and pol- ished with fine 000 emery paper followed by a cloth bob with rotten stone, etc., and water or oil. Blot- ting paper, charged with the above or with tripoli, is excellent for polishing small surfaces by hand. Ebonite is a good connecting material between softer rubber and iron, the whole being vulcanized together ; the iron should be well roughened or cut into rasp-like or file-like projections. Ebonite is properly the name for black hard rub- ber, and vulcanite for the colored products such as used by dentists and others. GUTTA-PERCHA. Gntta-percha is prepared by coagulation from the jnice or sap of several trees, among others the Isonandra gutta, of Borneo and the East Indian Archipelago. The product gutta-percha is iden- tical in composition with india rubber. It is hard at all ordinary temperatures. Its manufacture includes purification and masti- cation. It is far more amenable to treatment than is india rubber. Many materials are mixed with it as adulterants or otherwise in the factories. It is more useful in the form of sheets. These when heated to 122° F. (50° 0.) become pliable and can be moulded by pressure to any degree. At the 112 RUBBER HAND STAMP MAKING temperature of boiling water it becomes pasty and adhesive, and at 266° F. (130° 0.) it is so soft that it may be considered as melted. It is an admirable moulding material. Stereo- types and other relief or intaglio images can be made by pressing it while heated. These are often absolutely perfect reproductions of the original. Dishes for photographic purposes, etc., are easily made out of the sheet. By gentle warming they become pliable, and a greater heat makes surfaces capable of adhering by pressure. Tubes can be made by the squirting process, as used for india rubber. Wires are coated with it in a similar manner. It has several defects. It is not durable if ex- posed to the air with consequent changes of temper- ature. It is also too easily softened by heat, as of course no hot liquid can be introduced into a gutta- percha vessel. The Parkes cold curing process can be applied to it, which makes it more inditferent to heat. This is applied by dipping an instant and drying. After several repetitions the period of dip- ping is prolonged and ultimately it is left immersed some time. If left immersed at first it would dis- solve. It is soluble in most caoutchouc solvents, particu- larly in carbon disulphide. CHAPTER XIV. GLUE OR COMPOSITION STAMPS. Stamps made from a mixture of glue, glycerine, and molasses or from similar mixtures are a,n excel- lent substitute for iudia rubber stamps. Properly made they possess all the flexibility that character- izes the rubber ones, while for fatty inks such as that used by printers and lithographers, which inks tend to destroy rubber stamps, they are much better. They are adopted by the United States government for making dating stamps for use in the Post Office Department ; by publishers of directories for print- ing advertisements on the edges of their publica- tions, and in many other cases. Our description shall follow as closely as possible the process and methods used in the United States Post Office. They are there termed ^^composition blotters." The composition of which they are made is print- er's roller material. Nine and one-half pounds of fine quality glue are soaked in just enough soft water to cover it until it is thoroughly softened. It is then melted. In the Government Department a steam kettle is provided for the purpose. An ordinary glue pot will answer for smaller quantities. 114 RUBBEB HAND STAMP MAKING Wlien melted four and one-half pounds of best molas- ses and seven pounds of glycerine are added^ and the whole is thoroughly mixed. The formula varies a little according to the prevailing temperature, less molasses being added when the weather is warm, and vice versa. Experience is here the best teacher. Wlien well mixed it is poured out into tin pails whose inner walls or sides and bottom have been Model for Composition Stamp Mould. rubbed over with oil. It solidities in cooling and becomes a clear brown jelly quite free from any stickiness or superficial moistness. In use it is turned out of the pails to which, owing to the oiling, it does not adhere. It is cut off as wanted, melted by heat and cast in oiled moulds. The latter are made of type metal to which one- third its weight of lead has been added. As model ANB THE MANIPULATION OF RUBBER. 115 for the mould or matrix a brass model of the stamp is employed. This represents a sort of oval based cut-off or truncated cone, about an inch high and a little over an inch long on its base. A flanore extends outward from its base and a tube is provided to fit this flange. Its smaller end corre- sponds to the face of the stamp, and on it are en- graved in full relief an}^ permanent characters, Composition Stamp Mould. circles or border lines, etc. Through its centre one or more apertures are made. Into these, changeable steel, iron or brass type may be introduced and set fast with plaster of paris. To make the mould, the brass model with its mov- able type set as required is placed upon a flat table or plate, face upward, and surrounded by the tube, as shown in partial section in the cut, page 114. The tube is a strij) of sheet iron, which is bent around the flange and is secured in place by a wire twisted around it. The melted alloy (type, metal and lead) is 116 RUBBER HAND STAMP MAKING poured into the space thus formed until it rises a quarter of an inch above the face of the model. In a few minutes it sets and is removed and allowed to cool. This gives a cup with the inscription and* design dej^ressed or in intaglio upon its inside base. This is shown in the cut, page 115, partly in section; it will of course be understood that the mould forms a complete cup. To make the stamp the interior surface of the mould is oiled with a stiff brush. It is not material what oil is used. The composition melted by heat is then poured into the cup, and is allowed to solidify. Owing to the conical shape of the mould it is readily removed. The mould must be hot but not too much so. In the Post Office stamps the date requires to be changed frequently. Some of the figures do duty for two or three days each month. Thus the figure 8 is in the designation of three days, the eighth, eighteenth, and twenty-eighth. There are three changes involved therefore in connection with this day numeral. "When a stamp mould or matrix is cast the place of numerals that are to be changed is filled with a blank space in the part where the type would otherwise come. A number is stamped 'u\ this space when needed, by means of an ordinary steel number-punch. When the number is to be changed the old char- acter is scraped or cut out, leaving a small irregular hollow. A very small piece of soft lead, about one- AND THE MANIPULATION OF RUBBER. 117 sixteenth of an inch on each side, is dropped into the hollow. With a flat faced punch it is flattened out, and on it the new number is impressed by a steel punch. This operation is repeated a great many times before the matrix is worn out. OPEN, Composition Stamp Handle. In the cut, page 115, one number is shown as stamped into the soft lead, and at the other end of the stamp is a blank space ready for a number. The casting of a stamp is so extremely simple that no attempt is made to use movable type, as in permanent rubber dating stamps. While it is obvious that these composition stamps could be attached directly to wooden handles, a spe- 118 nUBBEtt HAND STAMP MAKING cial style of handle, shown in the cuts, is employed by the Post Office. A wooden handle carries at its end a brass base, to which is pivotted a swinging piece that is perforated by a conical oval ajDerture a little larger than the small end of the stamj). The edges of this aperture are slightly rounded. It is swung around as shown in the first figure, and the stamp, previously moistened on its sides, is forced in. If the stamp is properly made it is sur- prising how much force may be used to insert it. If the edges of the brass swinging piece ai»e not rounded there is danger of the composition being cut. The stamp in its brass frame is then swung back over the brass base, where it is secured by a catch. The stamp is now ready for use, as shown in the second figure of the cut. It is imperative that no aqueous or glycerine ink be employed for continuous work with such stamps. Common printers' ink is perfectly satisfactory, and the work may be nearly or quite as good as that ex- ecuted by an india rubber stamp. The Post Office manufactures a pad for use with printers' ink into whose manufacture the same com- position enters. The ink retainer is a piece of fine felt, one-quarter to one-half an inch thick. This is placed in the bottom of a shallow steel mould, where it enters for half its depth into a recess that it ac- curately fits. The comj^osition from old stamps, melted up, is then poured upon and around it, the mould being previously oiled. When it is full a AND THE MANIPULATION OF RUBBER, 119 piece of strong manilla paper, of the area of the felt only, is placed upon the bottom of the glue pad on its centre, which as it lies in the mould is its upper- most part. The paper adheres strongly as the glue hardens. Eventually it is turned out of the mould, and a pad, shown in the cut, is produced. The dotted lines show the limits of the felt pad. The glue composition underlies, surrounds and extends outwards from the felt portion. It is found that the elasticity of the composition makes the pad Composition Ink Pad. much pleasanter for rapid stamping. The above description gives the clew to making any stamp of this description. The matrix may be of dental plaster, or of oxychloride of zinc cement. The mould may be built up of type of any kind. The composition is so cheap that the stamp can be made quite thick. This gives it a high degree of elasticity and adaptability to uneven surfaces. It may be mounted by adherence upon a flat board or block, provided, if necessary, with handles. If the 120 RUBBER HAND STAMP MAKING. board or block is placed upon the composition while it is still warm and liquid, as it solidifies the board and composition will adhere with great tenacity. All moulds or surfaces to which it is desired that the melted composition shall not adhere must be oiled. The moulds must not be cold or the composition will not enter the fine divisions. If on the other hand they are too hot the mixture will adhere. Experience will teach the right conditions for suc- cess. Below are given other formulae for roller composi- tion. The formula already given in this chapter is that used by the United States Post Office Depart- ment. I. '* Old Home Eeceipt:" Glue 2 lbs., soaked over night, to New Orleans molasses 1 gallon. Not durable, but excellent while it lasts. II. Glue 10^ lbs., molasses 2^ gal., Venice tur- pentine 2 oz., glycerine 12 oz. ; mix as directed above. CHAPTER XV. THE HEKTOGRAPH. For obtaining multiple copies of writing, the apparatus called the Hektograph or Papyrograph has been extensively adopted. In general terms it consists of a tray filled with a jelly like composition. Any imprint made upon the surface with aniline ink can be transferred to paper by simple pressure. The tray filled with composition is called the tablet. It is thus prepared. The tray may be made of tin or even of paste- board or paper, and should be about one half an inch deep. It may be of any size, according to the work it is to do. The composition is made from the best gelatine and glycerine. One ounce by weight of gelatine is soaked over night in cold water, and in the morning the water is poured off, leaving the swelled gelatine. Six and one-half fluid ounces of glycerine are now heated to about 200 F. (93 0.) on a water bath preferably, and the gelatine is added thereto. The heating is continued for several hours. This operates to expel the water and to give a clear glycerine solution of gelatine. The composition is then poured into the tray, 1-22 RUBBER HAND STAMP 31 AKIN G which must be perfectly level in order to obtain a a surface nearly even with the edge. It is then covered so as to keep off the dust. The cover of course must not come in contact with the smooth surface. In six hours it will be ready for use. The original copy that is to be reproduced is made upon ordinary paper in aniline ink. One formula for the ink reads as follows: Aniline violet or blue (2 R B or 3 B) 1 oz., hot water 7 fluid oz. ; dissolve. After cooling add alcohol 1 fluid oz. and glycerine j{ fluid oz., a few drops of ether and a drop of carbolic acid. Keep in a corked bottle. Other formulae are given in chapter XVII. The writing is executed with an ordinary steel pen. The lines should be rather heavy so as to show a greenish color by reflected light. The surface of the pad is slightly moistened with a wet sponge and is allowed to become nearly dry. The paper is then laid upon it and smoothed down. This is best done by placing a second sheet over it and rubbing this with the hand. No air bubbles must remain between the copy and the tablet, and the paper must not be shifted. It is allowed to remain for a minute or less and is then raised by one corner and stripped from the gelatine surface. It will have left the reversed copy of its inscription perfectly reproduced upon the tablet. At once a piece of ordinary writing paper of the desired size and quality is laid upon the tablet. ANB THE MANIPULATION OF BUBBER. 123 smoothed down, and stripped off, when it will be found to have taken witli it a complete copy of the inscription or writing. This is repeated over The Hektograph. and over again with another sheet of paper, until the ink on the pad is exhausted. Fifty or more good copies can be thus obtained. As soon as the work is completed the remains of the ink should be washed off with a moist sponge 124 RUBBER HAND STAMP MAKING. and the tablet, after drying a little, will be ready for a second operation. Some practice is required to ascertain the proper strength of the writing and degree of wetness of the surface. When the gelatine surface becomes im- paired it can be remelted in a water bath if it is not too dark from absorption of ink. French Minister ij of Public Worh Formula. — Glue, 100 parts, glycerine 500 parts, finally powdered kaolin or barium sulphate 25 parts, water 375 parts. Use a little hydrochloric acid in the water for washing off the pad after use. Hehtograpli Sheets. — Four parts of glue are soaked in five parts of water and three parts of ammonia until soft. It is then heated and there is added to it three parts of sugar and eight parts of glycerine. The mixture is applied to blotting j^aper. This is saturated with it, and successive coats added until a smooth surface is produced on one side. This is the side for reproduction. It is used like the regular tablet except that it is claimed that sponging off the writing is not necessary. Owing to the capillary action developed by the blotting paper it is sup- posed to be self-cleaning by standing. 1 CHAPTER XVT. CEMENTS. BETORE cementing vulcanized rubber the surface Uiould be roughened or still better it may be seared S a red hot iron. For bicycle tyres this is espe- ciallv to be recommended. dnent for Cut, m Bicycle Tyres, RMer Belts, ,fc._Carbon bisulphide, 5 ounces; g""^-Pf>-*^' ; ounces; caoutchouc, 10 ounces; fish glue, 2A ounces. After it is applied and has diied the excess can be removed with a wet knife. Bad outs should first be stitched up. p,-,,,, _ Bicycle Tyre Cement to fasten Tyres to Bwis Bqu^a'parts'of pitch and g^^-PT'- -^^tit together. Sometimes two parts of pi ch aie pie scribed. This cement has extended applica- "'Zmentfor Paper Boats --f for Men^mmM^^ Crooch -Fuse together equal parts of pitch and Xpe-ha,and'tothis add about 2 parts otin- feed oil containing 5 parts of l^">'''-g*^.. ^.^^^ ^1- the heat until the ingredients are uniformly com minded. Apply warm. Waterproof Cement.-^h<>^^^, 4 oz; borax, 1 oz, 126 BUBBER HAND STAMP MAKING boil in a little water until dissolved, and concentrate by lieat to a paste. Another. — 10 parts of carbon disulpliide and one part of oil of turpentine are mixed, and as much gutta-percha is added as will readily dissolve. Cement for Mending Hard Rul)l>er. — Fuse together equal parts of gutta-percha and genuine asphaltum; apply hot to the joint, closing the latter immedi- ately with pressure. Glue to Fasten Leather, etc., to Metals. — 1 part crushed nut galls digested 6 hours with 8 parts dis- tilled water and strained. Glue is macerated in its own weight of water for 24 hour§, and then dis- solved. The warm infusion of nutgalls is spread on the leather; the glue solution upon the rough- ened surface of the warm metal; the moist leather is then pressed upon it and dried. Marine Glue, Various Formulm. — I. Dissolve 1 part of india rubber in 12 parts of benzole, and to the solution add 20 parts of powdered shellac, heat- ing the mixture cautiously over a fire. There is great danger of conflagration. Apply with a brush. II. Caoutchouc, 1 oz; genuine asphalturn, 2 oz; benzole or naptha, q. s. The caoutchouc is first dis- solved (as described in chapter XII.), and the asphaltum is gradually added. The solution should have about the consistency of molasses. Cement for Vuicanized India RuMer. — Stockholm pitch, 3 parts; American resin, 3 parts; unmixed india rubber, 6 parts; oil of turpentine, 12 parts. 1 AND THE MANIPULATION OF BUBBER. 127 Heat and mix very thoroughly. More oil of turpen- tine may be added as required. Gutta-Percha Cement for Leather. — Soak gutta- percha in boiling water. Soften in benzole after cut- ting up for a day. Heat on a water bath until the greater part of the benzole is expelled. When cool it will solidify. Use by heating. Cement for Rulher Shoes. — (1) Chloroform 280 parts. India rubber (masticated) 10 " (2) India rubber 10 " Kesin 4 " Venice turpentine 2 " Oil of turpentine 40 " For first solution dissolve by mastication. For second, melt the finely divided gum with the resin, add the Venice turpentine and finally the oil of tur- pentine. Use heat if necessary. Mix both solu- tions finally. To apply, saturate a piece of linen with the cement and apply to the spot previously coated with the cement. As it dries apply a little more as required. A finishing varnish is given in the last chapter. Parkes' cold curing process may be applied as described in chapter XI. Chattertoyi' s Compound for uniting sheets of gutta-percha in cable cores and for general work with gutta-percha coated wires. — Stockholm tar, ] part; resin, 1 part; gutta-percha, 2 parts. Waterproofing for Wooden Battery Cells. — Resin, 4 parts; gutta-percha, 1 part; boiled oil, a little. [28 RUBBEK HAND STAMP MAKING. Another Formula. — Burgundy pitch, 150 parts; old gutta-percha in fine shreds, 25 parts; ground pumice stone, 75 parts. Melt the gutta-percha and mix with the pumice stone and then add the pitch, melting all together. Apply melted and smooth oft* with a hot iron. Cement for Celluloid. — Shellac, 1 part is dissolved in spirits of ca'mphor 1 part, with 3 to 4 parts strong alcohol. It is applied warm and the parts united must not be disturbed until the cement is hard. I CHAPTER XVIl. INKS. RUBBER STAMP INK. Aniline blue soluble, IB 3 parts. Distilled water 10 " Acetic acid 10 " Alcohol 10 " Glycerine TO '' For other colors the following aniline colors may be substituted in proportions given: Methyl violet, 3 B (violet) 3 parts. Diamond fuchsin I, (red J 2 " Methyl green yellowish 4 " Vesuvin, B (brown) 5 " Nigrosin, W (blue black) 4 " For very bright red 3 parts of Eosin BBN. are used. In this case the acetic acid must be omitted. In all cases the colors should first be rubbed up with the water in a mortar, and the glycerine should be added gradually. These inks will answer for the hektograph. Hektogrcqjh Ink. — Aniline color, 1 part; water, 7 parts; glycerine, 1 part. A little alcohol may be 180 RUBBER HAND STAMP MAKING used with advantage to dissolve the aniline color. It can be expelled by heating if it proves objection- able. Aniline Ink Vehicle. — Prof. E. B. Shuttleworth, of Toronto, Ont., suggests the use of castor oil in place of vaseline and other vehicles for typewriter ink. The aniline colors may first be dissolved in alcohol, and the solution may be added to the oil. They may also be dissolved directly in the oil in which most of them are soluble. IndeliUe Stamping hiks. — I. Asphaltum, 1 part; oil of turpentine, 4 parts; dissolve and temper with printer^s ink. The ink may be omitted, and solid dry color added. II. Sodium carbonate, 22 parts; glycerine, 85 parts; dissolve and rub up in a mortar with gum arable, 20 parts. In a separate vessel dissolve silver nitrate, 11 parts; in officinal aqua ammonia, 20 parts. Mix the two solutions, and heat to the boil- ing point, 212^ F. (100° C). After it darkens, add Venice turpentine, 10 parts. After applying to the cloth, a hot iron should be applied^ or it should be exposed to the sun. III. Dr. W. Eeissig^s formula: Boiled linseed oil varnish 16 parts. Finest lamp black 6 "• Ferric chloride (sesquichloride of iron) 2 to 5 " \ AND THE MANIPULATION OF RUBBER. 131 Dilute a little for use with varnish. After this ink has been removed, no matter how completely it can be detected by dipping the paper into a solution of ammonium sulphide. IV. Aniline black in crystals 1 part. Alcohol « 30 " Glycerine 30 " Dissolve in the alcohol, and add the glycerine afterwards. Shotv Card Ink. — Pure asphaltum 16 parts, Venice turpentine 18 *' Lamp-black 4 " Oil of turpentine 64 " Dissolve the asphaltum in the turpentine, and thoroughly mix. Stencil Ink. — Shellac, 2 ounces; borax, 2 ounces; water, 25 ounces. Dissolve by heat if necessary, first the borax alone, and then adding the shellac. To the clear solution add gum arable, 2 ounces. Color with lamp-black, with Venetian red, or with ultramarine, to suit the taste. Another formula gives shellac, 4 parts, borax, 1 part, and omits the gum arable. Co2njing Ink (for use without a press by simply pressing and rubbing with the hand), by Prof. Att- field, F.R. 8. — Use ink of any kind of extra strength. 1 132 RUBBER HAND STAMP MAKING This in many cases can be made by eva^jorating common ink down to six tenths of its volume. Then mix with it two tliirds of its volume of glycer- ine^ so as to restore the original volume. White Ink. — Barium sulphate^ or '' flake white ''^ is mixed with gum arabic water of sufficient thick- ness to keep it suspended^ at least while in use. Starch or magnesium carbonate or other white pow- der may be used instead of the barium sulphate. The powder must be of impalpable fineness. Wlu'fe Ink 0)1 Blue Paper. — A solution of oxalic acid in water is used for this purpose. It may be applied with a rubber stamp or with a common pen. A quill or gold pen is the best as a steel pen is soon corroded. The ink bleaches the paper wherever it touches it, giving white lines on a blue ground. Gold Inh. — Gold leaf with honey is gi*ound up in a mortar, best an agate mortar, or on a painters' slab with a muller. It is added to water, and thor- oughly mixed and at once poured off from the first sediments, filtered out, and washed. This is done to secure the impalpably finely ground gold only. The resulting powder is mixed with a suitable vehi- cle, such as white varnish or gum arabic water. Silver Inh. — As above, using silver leaf. Zinc Label Inh. — I. Verdigris, 1 part; ammo- nium chloride, 1 part; lamp-black, i part; water, 10 parts. II. Platinum bichloride, 1 part; gum arabic, 1 part; water, 10 parts. *l \ AND THE MANIPULATION OF RUBBER. 133 Diamond Ink for Etching Glass.— Tins consists essentially of hydrofluoric acid mixed with barium sulphate to the consistency of cream. The barium sulphate is quite inoperative except as giving a body to prevent the ink from spreading. It is applied with a rubber stamp or pen and allowed to remain for ten minutes or until dry. On removal of the white powder, the design will be found etched on the glass. The following is a formula for it. Saturate hydrofluoric acid with ammonia, add an equal volume of hydrofluoric acid and thicken witii barium sulphate in fine powder. H CHAPTEE XVIII. MISCELLANEOUS. To Soften and Restore India Rubier Hose, etc. — I. Dip in petroleum and hang up for a couple of days. . Repeat process if necessary. II. The above process is applicable to all articles, but is specified for hose. It is stated that old rub- ber that has become hard may be softened by expos- ure first to vapor of carbon disulphide, followed by exposure to the vapor of kerosene. The latter vapor is found to be a general preservative for india rubber. III. Dr. Pol recommends immersion in a solution of water of ammonia, 1 part, and water 2 parts, from a few minutes to an hour. To Prevent Decay of RuMer TiiMng. — The decay of rubber tubing has been attributed to the forma- tion of sulphuric acid from the sulphur mixed with it. M. Ballard has suggested washing with water or weak alkaline solution five or six times in a year. Joints between India Rubier Tubing and Metal. — AV"here tubing is temporarily slipped over metal gas pipes and similar connections, as in the chemical lab- oratory, it is well to apjoly glycerine to the metal. THE MAmPULATION OF BUBBEB. 135 It acts as a lubricant in slipping the tubing on, and assists in its withdrawal. PmerH-«.9 F«Zca«t<«.-Wash occasionally with a soSnlf 'ammonia and rub with a rag slightly mokteiied with kerosene oil. meet of Copper upon Bniber.-ln a paper read be- fore th eceiU meeting of the British Association, Sir William Thomson stated that metallic copper, then "ed to the temperature of ^o' "'§ -f/' - lontact with the rubber, exerted a d-tnicU efl^c nnon it With a view to finding whethei this was ■ d^ t t JLpper per se, or to its power of con „c - ing heat more rapidly to the rubber, he '-^ » ^J^ batoi at iou r , platinum had be- ';Z, while tL rubber under the silver an nndei t-rt^C iiX- L ttuli nSlii c copper had sing aetln in the rubber without itself perme- ating it. 136 nUBBEH HAND STAMP MAKING Gas Tight Tubings. — Fletcher has invented a gas tight rubber tubing in which a layer of tinfoil is in- terposed between two concentric rubber tubes, all vulcanized together. Printing Colon's uj)on India Rubber. — It ma}^ some- times be desirable to have a surface of vulcanized In- dia rubber so prepared that it will take colors such as are used for calico printing. This end is simply at- tained by sprinkling the article with farina before vulcanizing. A small quantity attaches itself and forms an excellent base for color printing. Gutta-Perclia for Coating Glass. — For focusing glass in photography and for similar purposes where ground glass or a translucent material is required^ a solution of gutta-percha in chloroform is highly recommended. This is flowed over or painted on the glass and is allowed to evaporate afterwards. Burned Rubber. — A very soft pure gum sold for artists^ use is improperly termed burned rubber. It is used in crayon work for removing and lightening marks by dabbing it against the paper, cleaning the rubber from time to time. It is so soft that it picks up and removes crayon marks without the necessity of friction. Thus the rubbing out or more properly erasing operation can be localized and crayon tints can be lightened in tone without impairment or •^smutting." It is a very elegant accessory to the artists' paraphernalia. To make it^pure virgin gum, preferably the best Para, is cut into pieces and soaked for some hours in benzole. A Jong soaking is ad- AND THE MANIPULATION OF RUBBER. 137 visable. The pieces are then removed from the ben- zole and are ground in a mortar until perfectly hom- ogeneous. The mass is gathered up with a spatula and is pressed into little tin boxes. If desired it may be dried upon a water bath. This is not nec- essary as, if the box is left open, it will rapidly season itself. It should be very soft, should tend to adhere to the fingers, yet should leave them easily, and should strip cleanly from the box. A very little turpentine makes it more adhesive. It may even be softened in turpentine alone. This gives a gum that seasons more slowly and is in some respects pref- erable to the benzole made preparation. It is sold at a high price by the dealers, as the demand for it is limited. Rubber Spoufje.— This is also an artist's rubber. It is also used for cleaning kid gloves. It is made by incorporating with the masticated or washed and sheeted gum any material or materials that will give off vapor in the curing process. Damp sawdust and crystallized alum are used as giving off vapor of water or steam, or ammonium carbonate as giving off vapors of ammonia carbonic acid gas and steam. The mixed gum may be cured in moulds, which it will fill by its expansion. Shellac Varnish for Bidia Eubber.— This is made by soaking powdered shellac in ten times its weight of strong aqua ammonia (26'^ B.). At first no change beyond a coloring of the solution is percep- tible. After many days standing the bottle, which 138 IWBBEB HAND STAMP MAKING should have a glass stopper, being tightl}^ closed, the shellac disappears, having entered into solution. It may be a month before complete solution. This forms an excellent varnish for India rubber shoes and similar articles. It may be applied with a rag. It is also a good application for leather in some cases and doubtless many other uses could be made of it. It would act well as a vehicle for a dark pigment such as lamp-black. It will reju- venate a pair of India rubbers very nicely. The ammonia exercises also a good influence on the rub- ber. It has been recommended as a cement for attaching rubber to metal, but its adhesive powers are not always satisfactory. Simple Suhstitnte for Stamps. — A very simple though rough and imperfect substitute may be made by gluing with common car|)enter^s glue pieces of thick string upon a piece of wood, the string being given the form of the desired letters. Care must be taken to avoid saturating and stiffen- ing the string with the glue. India Rubber Substitutes. — One of these under the name of vulcanized oil is thus described by Bolas: ^' Vulcanized oil is, perhaps, of more interest, and many oils, such as linseed and others resembling it, i;iay be vulcanized by being heated for some time to 150° Centigrade with twelve to twenty per cent, of sulphur. The product obtained is soft, and some- what resembles very bad India rubber. By increas- i AND THE MANIPULATION OF RUBBER. 139 ing the proportion of sulphur very much indeed, say to four times the weight of the oil, and vulcanizing at a higher temperature, a hard substance, resem- bling inferior vulcanite, is obtained. ^^Soft and hard vulcanized oil have been intro- duced into commerce at various times and under many names; but these materials never seem to have made very much headway/^ Another method of treating the oil consists in mixing it with a solution of chloride of sulphur in carbon disulphide or in naptha. On standing, the volatile solvents escape, leaving a thick mass, which is the substitute. In combinations of aluminum with the fatty acids, forming aluminum soaps, and of these, alu- minum palmitate especially, a substitute for india rubber has been sought but without success. Metallized Caoutchouc. — Un vulcanized gum is mixed with powdered lead, zinc, or antimony. The mixed india rubber is then cured as in the regular process. EMEKY WHEELS AND WHETSTON^ES. Bolas thus describes their manufacture: '^ When ordinary vulcanized rubber is heated to 230° Centigrade, (446° F.) or until it melts, a per- manently viscous product is obtained, and this sub- stance, if mixed with emery and sulphur to a kind of paste, forms a material out of which the so-called agglomerated emery wheels or grinders may be 140 RUBBER HAND STAMP MAKING formed, the mixed materials being next hardened or cured by the application of a steam heat. Emery wheels and hones made on this principle were intro- duced by Deplanqne about twenty-three years ago. " Thirty-five parts of old vulcanized caoutchouc having been placed in a kind of still, heat is applied to melt it, the operation being assisted by the grad- ual addition of about ten parts of heavy coal oil; but this latter is afterward distilled off. The soft- ened caoutchouc is then incorporated with 500 parts of emery of the required degree of fineness and nine parts of sulphur. These materials having been thoroughly mixed, the hones or wheels are manufactured, and afterward cured or baked at a heat of 140° Centigrade, (284° F.) during a period of about eight hours. Grinding wheels, made in the above manner, can be worked at a speed of 2,000 revolutions per minute, and are extremely useful for the working of hardened steel or other obdurate materials.^'' Etclnng on Metals and Glass. — India rubber stamps can be used for placing the ground upon knife blades and similar articles which are to be etched. The parts untouched by the stamp are attacked by the acid. In the case of glass, diamond ink (page 133) can be put on with a stamp. The acids for metal etching might be thickened with barium sulphate also and applied in tlie same Avay. In these cases the inscription of the stamp would be etched. Where ground is put on, whether on glass or 1 AND THE MANIPULATIOy OF liUBBER. 141 ruetal, the design for the stamp will be pro- '"mcinny Ground for ^^''^..-^'in^^Ff^f^ „halt Bui-crundy pitch and beeswax melted togethei ifmfxed^thoLlghly. I* -^ ^^ ^^oter i 1 ' mutton suet. Beeswax may be used, dissolved in "her or simply melted. Yellow soap is sufticient for ordinary work. ^^^^ Etclnng Solutions SO', Bitmg m. '" . , iron, a. sulphate of copper ^'"^ '^«'""\°: ^f t ~ tion h. sulphate of copper, sulphate ot ^ilum" ^' and common salt, of each two drachms; acetic acid lioz. c. sulphuric acid, diluted with five vol- umes of water with a little sulphate of copper For other metals, except gold and platinum, nitric ■Ao\<\ diluted with five -volumes of water. i^S Ground for Glass.-MeMeA beeswax i. .enerai? recommended. It can be removed wrtl fpwis of turpentine after as much as possible has bv exposing it to the vapor ot hydrofluouo acid. ?shaUowLden tray, as large as the g -s, is r- auired. A quantity of fluorspar is placed in it and ■s mo stened vvith concentrated sulphuric acid. The gla sis placed face downward over tbe tray. I Liinorted over the mixture by resting on t he Td'g s oflbe tray or by any simple method, an tlie whole is covered with a towel. In half ,^^ h°;" ^ more the etching will be completed. The vapoi. 142 BUBBER HAND STAMP MAKING. must not be allowed to escape into any room con- taining glass or metal articles as they corrode every- thing. Great care should be taken also not to let the mixture touch the hancl^ as painful ulcers are the result. India Rubber Shoe Blacking. — Kaw india rubber is given as a constituent of several shoe blackings. Formulae are given as below for paste and liquid blackings. I. Paste blacking: bone-black, 20 parts; molasses, 15 parts; vinegar, 4 parts; sulphuric acid, 4 parts; caoutchouc oil (as given below), 3 parts. II. Liquid blacking: bone-black, 60 parts; mo- lasses, 45 parts; gum arable dissolved in water, 1 parfc; vinegar, 50 parts; sulphuric acid, 24 parts; caoutchouc oil, 9 parts. Caoutchouc oil is made by dissolving or digesting virgin rubber 55 parts in linseed oil 450 parts. ]¥aterproof Composition for Boots. — One ounce of virgin rubber cut into pieces is digested in enough oil of turpentine to form a stiff paste. In applying heat take great care lest the contents of the vessel become ignited. When homogeneous, which con- dition may be brought about by rubbing in a porce- lain mortar, as described in chapter XII., it is mixed with 5-6 ounces of boiled linseed oil. This gives an ointment almost of the consistency of butter. INDEX. PAGE Absorption of sulphur process.. loo Absorption of water by india rubber 3' Africa, ways of collecting rub- ber sap. 15-17 Analysis of sap of india rubber 27 Apparatus for stamp making. 61-63 Artists' burned rubber 136-137 95 Balloons^ . • • • - ^^\ _ temperature of Bands, india rubber 41 | '^unug, f _ _^^ ^ i'age Composition for stamps and its moulding "3-I20 Composition inking pad.... 118-119 Composition stamp handle . . 117-118 Cord, rubber 92 Corks 90-9^ Curing ^^ Curing-, how to.judge of com- pletion of 70 Curing in liquid bath 97 . • • • 99 .... 58 Curing in sulphur bath. Bicycle tyre cement Blacking, india rubber 142 Borax and water solution of rubber ^°6-io7 Brazil, ways of collecting sap. 20-21 Bromine as vulcanizer 100 Bulbs, how made 92-93 Burned rubber, artists' 136-137 125 1 Central America, ways of col- lecting rubber 1S-19 43 90 30 Calendering Cane tips Caoutchin Caoutchoucin 3° Caoutchouc, (see India Rubber.) Cements ^^S-i^S Clamp for vulcanizing press .... 52 Cohesion of rubber, its impor- tance to the manufacturer.. 26-27 Cold curing ^°°-^°^ Chair leg tips 9° Chalk plates ^3-84 Chlorine as vulcanizer i«d Chloroform as a solvent 105 Coagulationof sapby aplant... 19 Coagulation of sap by alum. . . .22-23 Coagulation of sap by fire. . - . 21-22 Coagulation of sap by salt. .... 18 Cohesion of pure rubber 25 D.-^TiNG stamps, composition. 116-117 Didot's polytype for matrices.. 82-83 Distillation products of india rubber ^9-3o Dolls, how made 92-93 Ebonite , ^°8-iii Ebonite, polishing iio-m 144 INDEX. Emery wheels and whetstones -. — 139- 140 Emulsion of caoutchouc ic Etching 140-142 Fins, removal of 86 Flask for type moulding 74 Flong matrices 80-82 Flong paste . . 80 Fluid for mixing with plaster for matrices 55 Gas heated steam vulcanizer . . . . 53 Glue, marine 126 Glue stamps 113-120 Glycerine bath for curing 97 Goodyear, Charles 13-14 Gutta-percha 111-112 Gutta-percha, moulding 111-112 Gutta-percha, vulcanizing m Hektograph, composition 121-122, 124 Hektograph, how made and used 121-124 Hektograph ink (also see inks).. 121 Hektograph sheets 124 India Rubber, absorption of water by 31 India rubber, African 15-17 India rubber, artists' burned 136-137 India rubber, availability for small articles 85 India rubber, cohesion of unvul- canized , 25 India rubber, composition of 27 India rubber, discovery of, etc. 11-13 India rubber, effects of temper- ature on 28-29 India rubber, elasticity of India rubber sap, its coagula- tion »' India rubber sheet, how made. . 40 India rubbers, original way of making 10 India rubber stamp making with- out apparatus 71 India rubber stamps, home-made mould 48-50 India rubber stamps, starting point 47 India rubber, trees producing.. 9 India rubber tree sap, analysis of 27 India rubber type 73 India rubber, vulcanized, general properties of .... 32-33 India rubber, where collected, 11 India rubber, inelastic, how made 31 India rubber, its mastication. . 38-40 India rubber, manufacture of, 35-46 India rubber, necessity of dry- ing 38 India rubber, points to be fol- lowed in moulding small arti- cles 85 India rubber, preliminary opera- tions in manufacturing 35-36 India rubber, preserving, etc. 134-135 India rubber, properties of ... . 28 India rubber sap 9-11 India rubber stamp vulcanizing 58-60 Inelastic state of India rubber.. 31 Inks, special forstamping,etc. 129-133 Iodine and haloid vulcanizers. . . 100 Isoprene 30 Leaves, skeletonized as models. 92 Liquid bath curing 97 Machine for cutting sheet and threads 40 Machine for making mixed sheet 42-43 INDEX. 145 Machine for masticating 38-40 Machine for washing and sheet- ing 37 Mackintosh 13 Mackintoshes, how made 45-46 Marshmallow not for mixture with plaster 57 Masticated rubber, its easy solu- tion 103-104 Masticating in mortar with ben- zole 103-104 Mastication of rubber 38-40 Materials mixed with india rubber 43 Matrices, various kinds of, for stamps 80-84 Matrix for stamp-making. .. 54-55 Matrix making by casting 56-57 Matrix press 56 Matrix, process of making, for stamps 54-55 Mats 91-92 Metals, welding and cohesion of 25-26 Miscellaneous 134-142 Mixed sheet 42-44 Mixed sheet for stamps 47-48 Mould, home-made for stamps. 48-50 Moulding and curing stamps. . 58-60 Moulds for composition stamps, temperature of . 120 Moulds, material for 86 Naptha and volatile solvents, danger of 107 Naptha, solvent 104-105 Nicaragua, ways of collecting sap 19-20 Nitric acid as vulcanizer 100 Oil for composition stamp moulds - 119-120 Oil for mould face 55 Oils fixed bad effect on solu- tions 105 Oxychloride of zinc cement for matrices 57 Papier mach^ matrices 80-82 Paraffin and rubber 105-106 Parkes' process 100-102 Payen's solvent 105 Pencil tips, moulds for 89-90 Phenyle sulphide as softener of vulcanized rubber 106 Plaster dental for matrices 54 Press for moulding stamps, etc. 51-52 Press, gas-heated 52-53 Press, home-made 49 Press, matrix making 55-56 Products, general division of.. 35-36 Rods, stirring for laboratory. . . 95 Rubber, origin of name 12 Rubber, see India Rubber Salt bath for curing 98 Sap of india rubber tree, analysis of 27 Sheeting and washing 37-38 Sheet rubber, how made 40 Sheet rubber, its joining 94 Shellac for strengthening matrix Shoes, blacking for 142 Shoes, india rubber, cement for. 127 Siphonia, origin of name 1 1 Solution, different views of. . . 31-32 Solution, difficulties of 103 Solvents for rubber 104-105 Spring chase for matrices 36 Springs for stamp moulds 51 Springs on moulding press. .. ,. 51 Sponge india rubber 137 Stamp making 47 146 INDEX. Stamps, rubber, substitute for. 138 Stamps, see India Rubber, Com- position and general titles. Strauss' method of coagulating sap 22-23 Suction discs, regular mould for 88-89 Suction discs, simple mould for 87-88 Sulphides, alkaline as vulcaniz- ers 100 Sulphur, absorption process 100 Sulphur bath for mixing and curing 98-100 Sulphur chloride process 100-102 Sulphur, how mixed with gum.. 43 Sulphur, its escape from vulcan- ized rubber .^3-34 Sunlight excluded from washed sheet rubber 38 Syringes made by Indians 11 Test for curing with knife 48 Thread, rubber, cut 41 Thread, rubber, moulded 92 Tissues, coated, how made. .. . 45-46 Tubes, connecting glass. 96 Tube, seamless 92 Turpentine, a solvent for vulca- nized rubber. 106 Turpentine compared with caoutchoucin 30 Turpentine, viscid nature of solution 104- T05 Type, india rubber 73 Type moulding flask 74 Type and stamps from vulca- nized rubber 77 Type, cutting apart 75 Type, points in moulding 75 Type, quads, and spaces for stamp models 71-72 Type, steel moulds for 76 United States composition stamps 113-120 Varnish shellac for india rub- ber 137-138 Vulcanite 108-111 Vulcanization, its two steps 42 Vulcanization, steps in pro- cess 47-48 Vulcanized rubber stamps and type 77 Vulcanizer 52-53 Vulcanizer, fish kettle as a. .. 69-70 Vulcanizer, flower pot 68-70 Vulcanizer, chamber 63 Vulcanizing and moulding stamps 58-60 Washing and sheeting 37-38 Water absorbed by ind ia rubber. 3 1 Waterproof composition for shoes 142 Waterproofing for battery cells 127-128 Zinc, chloride 57 ^A.E.XTHIDVnET'IO 03^ By T. O'Conor Sloane, A.M., E.M., Ph.D. HIS work gives the practical Electric Calculations in such a simple manner that they can be used by ^ any one having a knowfedge of Arithmetic. It L'cats of calculations for wiring; resistance in gene- arrangement of batteries for different work, heat- Jing effects of currents, calculations of size of fusible safety catches, electro-plating calculations, voltage of untried combinations, and distribution of M^ork in com- pound circuits, and all other practical calculations of heat, work and energy; and is supplemented by the most practi- cal series of tables ever published. In a separate chapter the deductions of the rules are given. Each rule after statement and explanation is followed by one or more fully worked out practical examples. It makes Electrical Calcu- lations intelligible to all, and may justly be said to fill a new field. It is absolutely indispensable to the working electrician, as well as to the professor, scientific teacher, student and amateur. Fully Illustrated. Price, $ 1 .OO. NORMAN W. HENLEY & CO. p. O. Box 327 1 , 150 NASSAU STREET, NEW YORK. GEO. R. BLAKELY, % Manufacturer of BANKING AND COMMERCIAL RUBBER * STAMPS «■ STENCILS, SEAL PRESSES, WAX SEALS, * * BURNING BRANDS, DOOR PLATES AND * « HOUSE NUMBERS, BAGGAGE AND * * KEYCHECKS, SOLID AND METAL- * * BODIED RUBBER TYPE, SOLID 4C- * RUBBER DATES, NUMBER- * ^ ING MACHINES, DATING * « STAMPSOFALLKINDS, ^ * CLOTHING STENCILS, PRINTING * * WHEELS, ETC. * IF IN NBED OF ANY OF THE ABOVE, PLEASE WHITE FOB, SAMPLES AND PBICES. BRADFORD, McKEAN CO., PA. PRACTICA L TRADE M ANUALS. Copley's Plain and Oruameiital Alphabets.— Examples in eveiy style, Mechanical and Analytical Construction of Letters. Designs for Titles. Ciphers. Monograms, Borders, Compasses, Flour- ishes, etc. iVe?f Edition . 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MANUFACTURERS' OUTFITS AND ALL MATERIALS. ^fe i i VULCANI2ERS, MOULDING RUBBER, i PRESSES, INKS, 1 * ^^H PEN dl PENCIL HANDLES, ^^^ STAMPS, MOULDING COMPOUND, 1 la II,, * AND EVERY REQUIREMENT SELF-INKING 1 1 FOR THE STAMPS. ^^ 1 MANUFAC- POCKET I^rii TURE OF RUB- STAMPS, ' Bi^ 1 BER STAMPS. SELF-INKING Ia 1 SEND FOR PADS. It ^ A CATALOGUE. i > AND MANUFACTURERS OF THE FOLLOWING SPECIALTIES: Steel Type for Type Writers, Steel Letters and Figures for the Hardware Trade, Brass and Iron Dies for Printing on Wood, Stencil Plates of every Description, Burning Brands, Seals of all kinds. Rubber and Metal Stamps. NUMBERING MACHINES, CHECK PROTECTORS, BAGGAGE CHECKS, KEY CHECKS, STEEL STAMPS, BRASS LABELS, RIBBON STAMPS, STEEL TYPE. BRASS TYPE, STENCIL DIES, STEEL DIES, STENCIL BRUSHES, INKS AND MATERIALS, REVOLVING STEEL STAMPING FIGURE WHEELS, RAILROAD SEALS, RUBBER TYPE, SOAP DIES AND STAMPS. IDIE SI3Sri5ZEI?,S -A-lSriD C3-E3SrEI?,-A-Xi ZEnSTGI-U.-A-'VEIiS. NEV^ YORK STENCIL WORKS, r». O. 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