Lumber-cored plywood was prepared with paraserianthes falcataria as a core wood, which was impregnated with disodium octaborate tetrahydrate (DOT, Timbor^®), and its preservative effectiveness was estimated in the laboratory test. Pressure treatments with 0.12-0.5% DOT provided P.falcataria with high permeability, and mean liquid uptake of this timber species ranged from 607 to 651kg/m³.
DOT penetration into the overall cross section at the central part was observed for all specimen tested. treatment. Retention of DOT, expressed as boric acid equivalent (BAE), in the central part of a specimen, however, was 60 to 70% of the retention at the end of the specimen. Laboratory decay test showed that the retention of DOT over 2kg/m³ BAE in core wood was required to inhibit attack by a brown-rot fungus, Fomitopsis palustris, and over 1kg/m³ BAE against a whiterot fungus, Trametes versicolor. Brush-treatment of face veneers or glue-line treatment was also effective in protecting lumber-cored plywood from decay fungi.

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