Weathering of wood modified with the N-methylol compound 1,3-dimethylol-4,5-dihydroxyethyleneurea

Infrared spectroscopy suggested that treatment of wood veneers with DMDHEU to high WPG (48%) stabilised lignin to some extent. Tensile strength losses of DMDHEU treated veneers during weathering were lower than those of untreated veneers. DMDHEU treatment, however, had a deleterious effect on the tensile strength of the veneers, possibly associated with the presence of magnesium chloride catalyst in the treatment solution. Scanning electron microscopy revealed that DMDHEU treatment was highly effective at preventing the degradation of the wood cell wall during weathering. Tracheids in unmodified veneers became distorted within 48 h of weathering exposure, whereas cells in modified veneers, especially those reacted to higher weight percent gains, retained their shape even after 144 h weathering.