Progress of discoloration in green, freshly cut veneer sheets of black alder (Alnus glutinosa L.) wood

Abstract

Black alder wood has a great potential for more wide-spread use in the woodworking industry. This study describes the colour changes that appeared the first few hours after cutting thin veneer sheets from fresh, unseasoned black alder wood. CIELab coordinates were recorded for 50 spots at time intervals from 0 to 140 minutes exposure of the fresh-cut surfaces. The most pronounced change was increased lightness developing from 20 to 60 minutes after cutting. A model for total colour change as function of exposure time was developed. Redness of veneer sheets increased only slightly, i.e. the expected transfer to orange discoloration of the surface did not occur. The reason for this was probably that part of the free water in the wood was squeezed out during veneer production. The findings of this study give useful information about the colour change that appeared directly after veneer cutting, advising to avoid excess water on wood surface and ensuring quick surface drying.