Artificial weathering of surfaces from laminated phenol-formaldehyde resin impregnated compressed wood: impact of top veneer type and overlay application

Panels from laminated phenol-formaldehyde resin (PF) impregnated and compressed wood (Compreg) with top veneers from European species of beech, maple and white birch were prepared, each without or coated with resin pre-impregnated overlay papers. To clarify the outdoor resistance of Compreg surfaces, long-term artificial weathering experiments were performed. Weather-related color changes, gloss retention and microscopic and surface topographical surface alterations were examined. It has been observed that the application of PF impregnated paper overlays and combinations of them with melamine formaldehyde resin (MF) treated films significantly improved the weather resistance of Compreg surfaces. The extent of UV and moisture-induced surface damages of Compreg has been shown to also be dependent on the veneer types used as surface top layer. Highest surface and color stabilization against weather was achieved providing Compreg with top veneers from maple combined with PF overlays or applying both MF and PF impregnated overlay films as surface finish.