Wood Properties of Nine Acetylated Tropical Hardwoods from Fast-Grown Plantations in Costa Rica

. The treatment of acetylation on tropical woods is in fl uenced by their different levels of permeability and how these affect the weight percentage gain (WPG) in acetylated wood. The objective of this study was to identify the effect of acetylation on physical properties, hygroscopic and dimensional stability, wetting rate, and durability of nine tropical species of hardwoods used for commercial reforestations in Costa Rica. The results showed that WPG varied from 2.2% to 16.8% among species. Positive signi fi cant correlations were observed between WPG and two parameters of dimensional and hygroscopic stability, whereas a negative correlation was observed with water absorption (WA). For species with a WPG of over 10% ( Vochysia ferruginea , Vochysia guatemalensis , Cordia alliodora , and Enterolobium cyclocarpum ) wetting rate, hygroscopic stability, and resistance to biological attack showed an increase while swelling, and WA decreased. For these species, the best behaviors were obtained with an acetylation time of 2.5 h. The same properties of wood in species with a WPG under 5% were found to be less affected by the different acetylation times and showed little difference in relation to untreated wood. Finally, the analysis showed that the dimensional stability obtained was attributed to the reduction of the absorptive capacity of the acetylated wood.