DETECTION OF REACTION WOOD (TENSION WOOD) IN WOOD-BASED PANELS MADE FROM POPLAR

Results of trials to differentiate between reaction and normal wood by colour reaction with zinc iodine complex in wood-based panels made fr om poplar lead to the following conclusions: 1. Tension wood is easily detectable in micro sections of impreg (presswood) as it reacts with zinc chloride iodine complex developing a blue colour using both the H ERZBERG and MERCK method. 2. In particleboards and fibreboards the dif ferentiation between tension wood and normal wood is difficult, as no significant colour differences between tension wood and normal wood we re observed. In general, however, tension wood was darker in colour af ter reaction with zinc chloride iodine complex. 3. After pulping and d efibration of particle- and fibreboards the tension wood in the fibres reacts with zinc chloride iodine complex to develop a blue colour. Us ing this method tension wood can be differentiated from normal wood, a s normal wood doesn't seem to react with zinc chloride iodine complex. 4. In general, tension wood is easily detectable in wood-based panels , which still retain the original biostructure of wood. However, it is difficult to detect tension wood in wood-based panels where the biost ructure of wood has been partially or completely destroyed. In this ca se, tension wood can only be detected after isolation of the fibres th rough pulping.