Relationship between wood colour of seven tropical hardwood species and formaldehyde emission of plywood

Abstract

There are many factors that affect the formaldehyde emission from plywood such as wood species and moisture content. As for wood species, colour appearance was found to affect significantly the formaldehyde emission. Therefore, the effects of tropical wood species with different colour on the formaldehyde emission of manufactured plywood were studied and determined by the perforator and desiccator method. Veneer of seven wood species, namely Mempisang, Kedondong, Penarahan, Keledang, Rengas, Melembu and Ludai were chosen as samples. 3-ply plywood were manufactured using urea formaldehyde as binders. The formaldehyde emission of the produced plywood was tested using perforator method (EN 120) and desiccator method (MS 1787: Part 15). Colour of the wood veneers were measured using Brightness & Colour Meter through CIE L*a*b* system. Relationship between the wood colour and formaldehyde emission were determined. The results revealed that the formaldehyde emission increased as the lightness (L*) of the wood samples increased. This may be due to higher extractive content in darker coloured wood (low lightness) that acts as formaldehyde scavenger.