Ultraviolet light and natural weathering vs. the compression strength of laminated wood

Abstract

Effects of protective measures were evaluated relative to the compression strength in the direction parallel to the grain of laminated veneer wood (LVL). For this purpose, laminated panels were prepared from Scots pine, Oriental beech, Castanea sativa, and sessile oak wood veneer by gluing them with Desmodur vinyl trie ketonol acetate (D-VTKA), polyvinyl-acetate (PVAc) dispersion D4 adhesive, resorcinol formaldehyde (RF), and melamine formaldehyde (MF). The samples were impregnated with a mixture of wax, linseed oil, and coated with a synthetic-based translucent varnish. The control samples (without the treatment described above), impregnated samples, and varnished samples were kept in the external environment for 1 y and in an ultraviolet (UV) environment for 240 h. The samples were tested to determine the air-dried density, retention amount, and compression strength. The results indicated that, in terms of outdoor conditions, the varnished proceeding provided better protection compared to the impregnated proceeding. The best result for compression strength was obtained on the Oriental beech samples with RF and MF glues. The ratio of the UV environment to represent the external environment was 89%.