In Brazil, fast-growth plantations of Tectona grandis L.f. are thinned prior to the final harvest (16 to 22-year cycle). Thinned trees have a small diameter, resulting in small dimension (transversal section) juvenile lumber, but with the formation of some heartwood.
Thermal modification is a suitable process to homogenize the color of sapwood and heartwood (Lopes et al., 2014a), as well as to improve the dimensional stability (Lopes et al., 2014b) and the durability of juvenile teakwood against rot-fungi (Pratiwi et al., 2019).
On the other hand, the process decreases surface wettability, mainly by reducing the number of primary sorption hydroxyl sites, which are degraded together with hemicelluloses (Hill, 2006). Wettability is a key factor regarding the quality of adhesion and finishings adherence, due to the interaction needed between these products and the wood surface (Tshabalala, 2005).
Discrepant results have been found in literature about the effect of thermal modification on surface wettability, due to the different processes and species studied (Jirouš-Rajković; Miklečić, 2019). The aim of this study was to assess the wettability of thermally modified sapwood and heartwood of teak.
Keywords: thermal modification, wettability, sapwood
Authors
Nayara Franzini Lopes
Djeison Cesar Batista
Georg-August University Göttingen, Göttingen
Rosilei Aparecida Garcia
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