SUMMARYThis study details information about physical, chemical and mechanical properties, drying, preservation and workability of wood from Cordia alliodora, Dipteryx panamensis, Enterolobium cyclocarpum, Hieronyma alchorneoides, Samanea saman and Vochysia ferruginea trees, growing in forest plantations in Costa Rica. Variation of the general properties in relation to height showed that heartwood percentage decreases, bark percentage increases and pith percentage is not affected. Dipteryx panamensis showed both the highest values for specific gravity and the highest mechanic resistance. Both chemical properties and extractives presence were different among species. Heartwood was not possible to preserve in any of the species, though sapwood was. Penetration varied from partial irregular or vascular in the species. The highest durability was for Hieronyma alchorneoides and Vochysia ferruginea, species classified as of high durability. Finally, all species had good performance in the workability tests. The previous results indicate that these species, used for trading reforestation in Costa Rica, have acceptable characteristics to be commercialized and used in wooden products.Key words: tropical species, Central America, wood variation, commercial wood. RESUMENEl presente estudio detalla información de las propiedades físicas, químicas, mecánicas, de secado, preservación y trabajabilidad de la madera de Cordia alliodora, Dipteryx panamensis, Enterolobium cyclocarpum, Hieronyma alchorneoides, Samanea saman y Vochysia ferruginea proveniente de plantaciones forestales en Costa Rica. La variación de las propiedades con respecto a la altura mostró que el porcentaje de duramen disminuyó, el porcentaje de corteza aumentó y el porcentaje de médula no se vio afectado por la altura del árbol. Dipteryx panamensis presentó los valores de peso específico más altos, por lo tanto, también presentó los valores de resistencia mecánica más altos. No fue posible preservar el duramen en ninguna especie, pero la albura sí y su penetración varió de parcial irregular o vascular en las especies. La mayor durabilidad se presentó en Hieronyma alchorneoides y Vochysia ferruginea, especies clasificadas como de alta durabilidad. Finalmente, todas las especies presentaron buen comportamiento en las pruebas de trabajabilidad. Los resultados anteriores indican que estas especies, utilizadas en la reforestación comercial de Costa Rica, poseen características aceptables para ser utilizadas en la comercialización y uso en productos de madera.

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Evaluación de la composición química, secado al aire, preservación y trabajabilidad de ocho especies de rápido crecimiento en plantación de Costa Rica AbstrAct Costa Rica has successfully planted various forestry species for wood production. However, the use of their wood is limited, due to poor knowledge about their chemical properties, air-dry, preserved and workability performance. The present study details information of these properties for the species: Alnus acuminata (Aa), Acacia mangium (Am), Bombacopsis quinata (Bq), Cupressus lusitanica (Cl), Swietenia macrophylla (Sm), Terminalia amazonia (Ta), Terminalia oblonga (To) and Vochysia guatemalensis (Vg). Among the results obtained, it was found that the wood of these species is in general slightly acidic, except Bq, which presented tendency to be basic. Different species show considerable variability in the content of holocellulose, lignin and extractable micronutrients. Regarding micronutrients, and in relation to other species it was found a high percentage in Vg. The use of boron as a preservative, may be applied in the 8 plantation species. The presence of heartwood in some species made it not possible to be preserved by the vacuum-pressure method, but the sapwood was possible to preserve in all species. The drying rate increased with increasing board thickness and drying time was different among species. The fastest drying rate was found in Ta and Am, followed by Sm, To, Aa and Cl with intermediate values and Vg with the slowest air-drying rate. Am, Bq, Cl, Sm and To present from excellent to good planing, sanding , drilling and molding, but Ta, Bq, Aa and Vg, especially Aa and Vg, in the workability operations were catalogued as poor or very poor quality.

This study evaluated wood color change (ΔE*) and the surface quality in 10 tropical wood species painted with three finishes (composed of wax and polyurethane). Two weathering conditions were tested: natural weathering (NW) and artificial weathering (AW). The results showed that the application of these finishes, decreased the luminosity (L*), increased the redness (a*) and the yellowness (b*) parameters in all species. ΔE*, after weathering exposure, was affected significantly by L*, a*, and b, whereas for finished or pretreated wood, L* and b* are the main parameters affecting ΔE* in the 10 tropical species studied. ΔE* values found in different finishes and pretreatments are cataloged as total change of color. Other important results were that tropical light colored timber with natural pretreatment produced higher ΔE* than dark colored timber. The stains and fungal development were observed in polyurethane finishes in NW, but not in AW. The irregular and mosaic flaws were not observed in any kind of finish or pretreatment of surface. The values of the quality index created, which considered long and short lines and switch flaws, were lowest in NW and in waxy finish, while the highest value was obtained with the polyurethane finish.

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