Gluability of Thermally Modified Aspen, Birch, and Poplar Rotary Cut Veneers with Suberinic Acids Adhesive

The eco-friendly lifestyle has gained traction at individual and industrial levels, especially following Europe's "Green Deal". While the woodworking industry in Latvia has made strides toward waste-free production, wood processing still produces by-products that require effective utilization. Instead of burning these residues for energy, a sustainable option is repurposing birch bark into suberinic acids adhesive, which is environmentally friendly and safe for humans. Research shows that thermally modified aspen, birch, and poplar veneers treated using the Termovuoto process at 160 degrees C/50 min, 204 degrees C/120 min, 214 degrees C/120 min, 217 degrees C/180 min, and 218 degrees C/30 min can be bonded with this adhesive and meet the EN 314-2:1993 standard for outdoor applications classified as Class 3 bonding. However, hydrothermally modified veneers treated at 160 degrees C 50 min do not bond successfully, failing to meet Class 3 requirements.