f\, /;/77* INFORMATION LEAFLET FOREIGN WOODS Forest Products Laboratory,— Forest Service U. S. Department of Agriculture 1950 U ,,0^^0^^ ^r NOV 3 LIMBA >* (Afar a, Frake*, Korina-) fcTt-ANT/- Terminalia superba Engl* et Diels ^-\ \ AN T * • Family: Combretaceae 7' qf ' fl l ib" JQCUMENTS DEPT. By : S. DEPOSITORY ELOISE GERRY, Forest Products Technologist" Division of Silvicultural Relations Terminalia superba Engl, et Diels is a West African species which is known by various common names. The specific name superba suggests the handsome appearance of the tree which is widely distributed from , French Guinea to the Cameroons, the Belgian Congo and Angola (l^, 19 )« It prefers the humid forests without a dry season. The name Terminalia refers to the leaves, which occur in tufts at the ends of the branches (19) Some of the common or trade names are (ljj) : White afara (United Kingdom and Nigeria) Limba clair or light limba Limba noir or dark limba— Limbo Chtne limbo Frake* Noyer du Mayombe Ofram - Gold Coast Korina— Belgium, Belgian Congo and Angola) ) France and French West AfricaN -Maintained at Madison, Wis., in cooperation with the University of Wisconsin. ^Trademarked name. (See Veneers and Plywood i+3(3) :26-27, Mar. I9U9. ■^Underlined numbers in parentheses refer to the list of numbered references at the end of this leaflet. --Black or dark afara is a name generally applied to Idigbo ( Terminalia ivorensis) because of its dark bark , its wood being pale yellow (15)» Report No. R177S Agriculture-Madison \ THE TREE Limba grows rapidly but is not very long lived (19.). It may attain a height of 150 feet or more and usually has an extremely straight clear, cylindrical stem, with a buttressed base which often extends 8 feet or more above the ground. Diameters, above the buttresses, may range from 3 to 5 feet. The tree may occur in nearly pure stands. Branches are produced in whorls; the tops of the trees may be flattish. The bark is ashy gray, scaly and fissured in older trees. Plantations made in West Africa appear to be succeeding and yields from managed forests are promising (6, 1^, 19 ) . At 20 years trees may have clean, straight boles 50 to 60 feet in height with a girth of about 5 feet. The trees coppice from stumps, are adaptable and reproduce naturally (20). They prefer good light for best growth (heliophile) and tend to be shallow rooted (^, IS) . The numerous small yellowish or whitish green flowers are in simple, axillary racemes. The fruits are abundant and in the form of samaras, each about 3/^-i n ch long, with a lateral spread of wing of 1-1/2 to 2 inches (20). THE WOOD Color Usually both heartwood and sapwood are light gray-white to pale creamy- brown in color, similar to light oak. Sometimes, however, the heartwood contains irregular grayish markings, with streaks that may be almost black; this wood may bring an extra price. The cause of these markings is not fully understood (19_, 2 !2) . For some purposes, the varied dark wood has been specially valued, and for others the light color is its chief asset (H) . The name limba clair (or limba blanc) is given to logs in which about two- thirds or more of the diameter is light in color, with heart color less than 10 centimeters in diameter (19). Limba noir (limba-bariole, or walnut of Mayombe) is the name applied to timbers in which the dark heartwood is large enough to show on the sides of the squared logs (15., 19) The name limbo demi-noir is given to irregularly veined material, with color on two- thirds of the diameter of the log (19). Weight Limba is reported to weigh about 35 pounds per cubic foot at 15 percent moisture content (15). Reports list specific gravity (oven dry weight and green volume) as 075b to 0.51 (6, 8), optimum O.5O-O.60 (18) , green, 0.75 (12). Report No. R1778 -2- Grain, Texture and Figure Limba is rated as generally straight-grained, although wavy grain may occur, producing a desired figure (15.)* The texture varies from close to rather coarse hut even (6) . Mechanical Properties In large logs the heartwood may be brittle, and as a rule the dark colored wood tends to be more brittle than the light. Complete strength tests have not been carried out<2. but the timber rates as not very strong, not as strong as oak (£, 1J5., 19) • 0* 1 © plank from Nigeria was tested in England (1) with the results given in the accompanying table. A very small number of tests on a few boards were made at the U. S. Forest Products Laboratory in 19^8. Wood with specific gravities of 0.515 *° O.6U5 gave values corresponding roughly with those for black cherry, black tupelo, red maple, and American elm. Seasoning Kiln drying is reported to be easily accomplished with little tendency for the development of defects. A schedule about like that for ash can be used—. The wood shows stability when manufactured. Care is required if the wood is air seasoned to prevent decay and discoloration (15). Shrinkage is reported to be rather small (1^) but greater in the dark colored portions. Durability Limba is not resistant to decay, insects, or termites (19) and the heart- wood of large trees is frequently found to be unsound, or even hollow, when felled (lU) • The sapwood stains readily in a manner similar to the bluing of softwoods. Logs are attacked by pinhole borers in both sapwood and heartwood. Powder-post beetles may attack sapwood (15). Preservative treatments are reported to prevent damage by fungi and insects (6). Working Characteristics The timber has been found to work easily with hand and machine tools? it turns well. If the grain is uneven it may "pick up" in planing, but this is said to be overcome by using a low cutting angle ( 15) . Limba veneers without trouble. The wood finishes well when a filler is used. It glues readily and does not "bleed" (5) but care is required in nailing and screwing, for the wood has a tendency to split (15)» 2Tests by the Forest Products Research Laboratories in England were made on a related species, Terminalia ivorensis (Idigbo), and are published in the periodical "Wood" (BritishJ~for July 1938 for purposes of comparison with other Gold Coast woods. §A. suggested schedule would be similar to No. 3 given in Technical Note 175» U. S. Forest Products Laboratory, Madison, Wis. Report No. R1778 -3- Summary of Results of the Mechanical Tests on Afara Wood ( Terminal ia sup orb a ) from Nigeria (l) A. — Transverse bending test (central loading) J Maximum Minimum Mean Maximum calculated longitudinal shear Lb./sq. in. 367*5 187. 5 286.5 Modulus of rupture Lb./sq. in. 10,230 5,225 7,9b8 Fibre stress at elastic limit. Lb./sq. in. 7.850 ^,138 .6,229 Modulus of elasticity Lb./sq. in. 1,3^5,000 1,192,000 1,272,000 Elastic resilience Inch-lb. /cu. in. 22.3^ 0.679 1«70 B. — Compression test along the grain (2U in. length specimen): Crushing strength Lb./sq. in. 6,000 5,260 5,620 Fibre strength at elastic limit Lb./sq. in. 5,1+75 U.125 *+,6l0 Modulus of elasticity Lb./sq. in. 1,233,000 1,213,000 1,223,000 Elastic resilience Inch-lb. /cu. in. 10*28 5*9^ 7*U6 C. — Compression test along the grain (8 in. length specimen): Crushing strength Lb./sq. in. 5,888 5,^75 5»738 Fibre strength at elastic limit Lb./sq. in. U.625 ^,500 U.567 Modulus of elasticity Lb./sq. in. 1,285,000 1,100,000 1,198,000 Elastic resilience Inch-lb. /cu. in. 7'*+5 6*^9 6«87 D. — Compression test across the grain: Load at elastic limit Lb. ^,700 U.200 ^,H00 Fibre stress at elastic limit. Lb./sq. in. 1,175 1,050 1,098 E. — Shearing tests along the grain: Radial — Maximum load supported Lb. *J-,710 k,^kO H,640 Shearing strength Lb./sq. in. 1,178 1,135 1,160 Tangential — Maximum load supported Lb. 6,1^0 6,050 6,100 Shearing strength Lb./sq. in. 1,535 1,513 lf525 Specific gravity 0*515 O'k^k 0*Hg6 Weight per cubic foot Lb. 32*2 28»U 30. k Moisture Percent 11*37 9*85 10 * 29 Report No. R177S ~^~ Uses The use of limba is increasing. It is used as solid wood and also as veneer and plywood, and is especially popular for blond furniture, school and shop fittings, radio and television cabinets, parquetry, and joinery. It has been used in construction but is too useful in other fields at present to be so used (k, 1^) . Limba is said to have been used in South Africa and in Germany for propellers and patterns, and has been given preliminary tests for pulp making (16) where rather high chemical consumption and dark stock were noted. However, this use is considered possible in the future, for it has been found to yield sufficiently strong kraft pulp (19) . Supplies Supplies are normally abundant. The wood is imported in logs up to 30 inches in diameter or planks up to 30 inches wide and lengths up to 20 feet (^, 1^_). Ports of export include Borne., Kouilou, Matadi, and Landana. Minute Structure Growth rings are usually distinct and often conspicuous on the end surface; they are usually undulating. The boundaries are marked by a band of darker tissue at the end of the growth zone. Sometimes a narrow, discontinuous band of soft tissue is present, visible under a magnifying glass. The pores are rather large, individually distinct to the naked eye. They are very few to few in number and rather evenly distributed, usually much smaller at the end of the growth ring. They tend to show as oblique lines; although mostly solitary, occasionally they appear in radial groups of 2, 3. or even h» On longitudinal surfaces the pores or vessels are conspicuous as deep scratches, occasionally sparkling. Tyloses .-— Br ight , iridescent tyloses are sometimes abundant. Parenchyma is moderately abundant, not very distinct to the naked eye. It is discontinuous but borders the pores and extends laterally, often linking them in wavy lines. Crystals are often present in the vertical parenchyma (19). Rays are very fine, not visible to the naked eye and inconspicuous even on radial surfaces. They are usually uniseriate (19). Fiber length is reported as 1.20 millimeters (average), and diameter 27.5 microns (l6) . Ash Although rich in ash, the proportion of silica is small (19) • Report No. R177S -5- List of References 1. Anon. 1923» Results of Examination of Nigerian Timbers-Afara "Bull. Imperial Institute 21(3) •M-^-UkZ 2. k. 1928. Nos Bois Coloniaux: Limbo. Asso. Colonies - Sciences et Comite National des Bois Coloniaux, hk Rue Blanche Paris. ( s ee Record, Tropical Woods 18:26-28, Yale University, School of Forestry, New Haven, Conn.) 1948. In California Lumber Merchant, May 1, p. k2 (U. S. Plywood Lmporters) 19^9* Prom the Belgian Congo to the American Home ("Korina")* Wood Working Digest 51(5): 171, May. Illus. 5. Brush, W. D. and Sparhawk, W. N. 19 ^3 • West African Timbers for use in North America. Unpublished material in U. S. Forest Service files. U. S. Department of Agriculture. 6. Chalk, L. , Davy, J. B. , Desch, H. E. , and Hoyle, A. C. 1933- Forest trees and timbers of the British Empire. II. Twenty West African Timber Trees, pp. 30~35 (illus.) Clarenden Press, Oxford, England (115 references). 7. Comite* National des Bois Tropicaux (l6 Rue de la Paix, Paris, 2 e ) 1931 (a) No. 1. Etude physique et me'canique des Bois Coloniaux. 132 pp. 1933 Ob) Premier complement. 25 pp. I9HU (c) Deuxie'me complement. 8. 9. 1949. Nos Bois Tropicaux - Limbo, pp. 22-23. 1949. Limbo. Bois et Forets des Tropiques No. 9 - l er Trimestre, pp. 63-66. 10. Cooper, G-. P. and Record, S. J. 1931* The Evergreen Forests of Liberia. Yale University, School of Forestry, New Haven, Conn. Bull. No. 31. 1 1 . Duche sne , Fl . 19^7» La Section Economique der Muse'e du Congo Beige. Annales du Musee du Congo Beige Tervuren Series in 8°. Sciences, Historiques et Economiques Vol. 1, pp. 161-162, Oct. Illus. Report No. RI778 -6- 12. He din, L. 1929» Sur quelques essences forestie'res exploiters au Cameroun. Rev. Bot. Appl. et d Agr. Tropicale 9»89:39~51 Jan. Paris (Tropical Woods 20 pp. U3-50). 13. Hutchison and Dalziel, J. M. 1927-1931. Flora of West Tropical Africa. Vol. 1, pt. 1, p. 226 (See Trop. Woods 18:27, 1929. T. superba Engl, et Diels = T. altissima Chev. ) See (3J5). Ik. Irvine, F. R. 1930. Plants of the Gold Coast. Oxford. 15» Jay, B. Alwyn 1950. Timbers of West Africa, 3rd ed. , pp. 8-10, Timber Development Asso. Ltd., 75 Cannon St., London E.C. h, 16. LeCacheux, Paul 19*+6« L'Utilizatidn des Essences Tropicales dans L' Industrie des Pates et Papiers. pp. I5I-I56 (Fiber lengths). 17. Meniaud, J. 1931* Nos Bois Coloniaux. Paris. 18. Meyer, Hans 1933. Book of Wood Names (Buch der Holznamen) N. & H.Schafer, Hannover, Germany. 19. Nc-rmand, D. 19^7. Le Limbo (Frake*) Revue du Bois 2(5): 3-6. Illus. May. (Transl. by E. Gerry) 20. Record, S. J. 1929. Walnut Woods — True and Palse. (Noyer du Mayombe or Congo walnut) Tropical Woods 18:4-29 (26-28). 21. Record, S. J. and Hess, R. W. 19^3* Timbers of the New World, p. 130, Yale University Press, New Haven, Conn. 22. Scott, M. H. I9U3. Some West African Substitutes for Well- Known Timbers. Jour. South African Forestry Assoc. No. 10:29-39. April. 23. Stone, H. and Cox, H. A. 1922. Timbers of Nigeria. Crown Agents for the Colonies, London. 2U. Unwin, A. H. 1930. West African Forests and Forestry. London. 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