Photodegradation of heat treated hardwood veneers.

This paper outlines an investigation pertaining to color changes of hardwood veneers exposed to elevated temperature. The effects of convection and contact type heat applications on the different species were separately evaluated. The experimental analyses included two-factor, three-level randomized block designs, where the factors were the temperature and the duration of the exposure. Examined species included: Yellow-poplar (Liriodendron tulipifera L.) and red oak (Quercus rubra L.). Two way analysis of variance (ANOVA) indicated major overall effects with significant interactions between the factors for all species/heat-treatment combinations. However, pair wise comparisons (Tukey tests) revealed lack of significant differences within factors for certain levels. The gained information might be useful for adjusting drying or pressing time/temperature relations. Setting the desired colors by necessary processing operations has certain technological, economical and environmental advantages. The use of additional chemicals to create dark surfaces may be reduced or eliminated.