ENVIRONMENTALLY FRIENDLY TEMPORARY ANTI-MOULD TREATMENT OF PACKAGING MATERIAL BEFORE DRYING

According to FAO - ISPM No 15, in international trade wood packaging material on the basis of sawn timber requires to be heat-treated to avoid spreading of harmful organisms. "Heat-treatment" means a minimum core temperature of the wood of 56° C for a minimum of 30 minutes. ISPM No 15 does not define moisture content and therefore does not include rules for the drying process. Practitioners report that fresh sapwood, after having undergone a pure heat treatment without any kind of drying, shows a great affinity to fungi (mould and blue stain). Even though the infestation does not affect the strength properties of the wood, it must be considered as an optical and a sanitary problem. An environmentally friendly, cheap and easy to use technique for temporary anti-mould protection of heat-treated wood is needed to bridge the time span between sawing, heat treatment and air or kiln drying. Results derived from laboratory experiments have shown that the heat-treatment affects the elution of the lipid components within pine sapwood. While searching for alternatives to conventional preservation methods, different environmentally compliant agents (particularly aqueous solutions containing sodium- and potassium carbonate) were found to inhibit the germination of mould and blue stain fungi spores on wood packaging material surfaces in a temporary manner. Besides their effectiveness, the usage of these agents to achieving the temporary protection (e.g. for a couple of weeks) is economically feasible and easily applicable in industrial practice. However, drying (either naturally or technically) is indispensable to avoid fungal hazard on the long run. A combination of temporary treatment immediately after sawing followed by a drying-process (long lasting protection) seems to be the most effective method to protect ISPM No 15 treated wood packaging material against mould