Penetration of liquid urea-formaldehyde adhesive into beech wood

The main objective of this research was to evaluate the penetration of a liquid urea-formaldehyde adhesive (UF) into beech (Fagus sylvatica L.) wood as 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 of 4 to 13%. Adhesive penetration was greater with samples that were cured in a conventional press when compared with high-frequency pressing. Penetration in the tangential direction was greater than in the radial direction. The application of mechanical pressure to the bondline greatly increased penetration, whereas extended open assembly times did little to increase penetration.