Penetration of liquid urea-formaldehyde adhesive into beech wood

The main objective of this research was to evaluate the penetration of a li quid urea-formaldehyde adhesive (UF) into beech (Fagus sylvatica L.) wood a s influenced by moisture content (MC) and the method of curing. The maximum penetration of the UF adhesive was detected at 9% MC within the MC range o f 4 to 13%. Adhesive penetration was greater with samples that were cured i n a conventional press when compared with high-frequency pressing. Penetrat ion in the tangential direction was greater than in the radial direction. T he application of mechanical pressure to the bondline greatly increased pen etration, whereas extended open assembly times did little to increase penet ration.