Tests and Properties of Tropical Woods

In contrast to the relatively limited number of domestic wood species, it is conservatively estimated that in the forests of Central and South America alone, there are over 10,000 tree species. Most tests of tropical woods have been directed to making practical use of particular species. However, the great diversity of tropical woods also provides a chance to increase our basic knowledge of the relationships between structure, density, moisture content, and the properties of wood. Two frequency diagrams show the proportionate distribution among specific gravity classes of 48 tropical woods and 168 domestic woods; most of the domestic species are found in the 0.30 to 0.60 specific gravity class, while many of the tropical woods fall into the 0.40 to 0.80 class. In both modulus of rupture and modulus of elasticity, tropical woods generally exceed values predicted by equations developed for unseasoned domestic woods. This is also true of the shrinkage-specific gravity relationship; at higher specific gravities, shrinkage, values for tropical woods are only about 3/5 as great as those predicted by equations used for domestic wood. Part of this difference may be due to a lower fiber saturation point in most of the tropical woods, though this hypothesis requires further testing. A “species profile” method of presenting a visual comparison of any wood under consideration with a wood of known use is illustrated. Some specific uses for tropical woods discussed are ship and boat decking, pattern making, and impact tool handles.

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