COLOR AND CHEMICAL CHARACTERISTICS OF MOON RINGS IN OAKWOOD

The moon ring defect of oak wood is thought to occur during the transf ormation of sapwood to heartwood. This false sapwood can cause serious losses to the wood industry. Several oak samples containing this defe ct were studied, each separated into: sapwood, outer heartwood, moon r ing and inner heartwood. Colour analyses were carried out by the CIELA B colour system, and phenolic and mineral components were also measure d. The analyses show that moon rings are more red in colour, and conta in higher concentrations of ellagic acid, than sapwood. Potassium conc entrations are lower in the moon rings compared with other zones. Hier archical and discriminant analyses of all the parameters studied confi rm the differences observed between sapwood and moon rings. The result s support the hypothesis that moon rings may be produced due to heartw ood formation being interrupted by traumas, such as severe frost.