METHOD OF MANUFACTURE OF FIREPROOF FLYWOOD Russian patent published in 2003 - IPC

FIELD: wood working industry. SUBSTANCE: non-dried rotary-cut birch veneer is impregnated in working solution of diammonium phosphate until 25-35% of dry salt is absorbed by veneer. After drying to moisture content of 8±2%, veneer is sorted out with separation of sheets with salt stains. Sheets with salt stains are dipped in washing solution of diammonium phosphate of reduced concentration of 10% and kept in solution for 3 min. As a result, content of fireproofing compound becomes equal to 22-27%. After subsequent drying, no salt stains on veneer are seen. Plywood glued from veneer said treatment also has no salt stains. EFFECT: provision of uniform distribution of fireproofing compound in veneer and prevention of formation of salt stains on surfaces of veneer. 2 cl, 1 ex