Fabrication and characterization of multi-functional plywood with flame-retardant, mold-resistant, and dimensionally stable properties via a one-step soaking process

The fabrication of flame-retardant, mold-resistant, and dimensionally stable wood using a one-step soaking process remains an imperative yet challenging goal. In this study, we developed a stable ternary composite solution system containing flame retardants (ammonium polyphosphate, boric acid, and borax), biocides (4,5-dichloro-2-n-octyl-4-isothiazolin-3-one and 2-octyl-4-isothiazolin-3-one), and a dimensional stabilizer (N-methylol acrylamide), which was employed for the soaking treatment of wood veneer for 2 h, followed by oven curing at 80 °C for 12 h. The limiting oxygen index of the optimal wood veneer reached 34.4 %, while shrinkage and expansion ratios were 2 % and 3 %, respectively. The optimal wood veneer exhibited 100 % anti-mold efficacy against Aspergillus niger , even after leaching tests. Plywood manufactured from the modified veneer retained the enhanced flame retardancy, mold resistance, and dimensional stability. The synergistic effects of the ternary system and the efficiency of the one-step approach highlight its potential for producing durable, high-performance wood products for demanding applications. This method offers an eco-friendly solution to enhance wood safety and longevity in construction and furniture industries. • This study presented a one-step soaking method for producing multifunctional wood. • NMA combined with a flame retardant and organic fungicide showed good stability. • The network structure formed by NMA facilitated the bulking of wood cell walls. • NMA exhibited a synergistic effect with flame retardant and organic fungicide.