2.1.4. Fabrication of engineered flooring board
The engineered floorings for the formaldehyde and VOC emission tests were manufactured using natural tannin adhesive and tannin/PVAc hybrid resin, with dimensions of 400 mm 400 mm 75 mm (length width thickness). After the resinwas spread on the plywood, 0.5 mm thick maple fancy veneer was bonded by cold- and hot-pressing. The pressure-time diagram followed three-stage schedule, consisting of preliminary coldpressing at 1 kgf/cm2 for 2 min. for assembly, main hot-pressing at 5 kgf/cm2 and 150 C for 160 s for resin curing, and final coldpressing at 1 kgf/cm2 for 2 min.