Ovalbumin has unusually good wood adhesive strength and water resistance

The interest in non-formaldehyde adhesives has reinvigorated studies using proteins from plant and animal sources, with an emphasis on plant-based sources, especially the oilseed plants such as soybean. Although animal-based sources have received much less attention, and ovalbumin from egg whites has not been studied at all, it provides a surprising low viscosity and high wet strength as a wood adhesive. Of the animal and plant proteins used in the past, egg protein has been used for centuries as a binder in tempera, for book illumination, and for gilding, but not as a water-resistant wood adhesive. The isolated ovalbumin is the best, but dried egg whites and whole egg have good adhesive strength. The parameters for ovalbumin wood bonding are examined with thin veneers using ASTM D 7998 and plywood tests using D 906. Sodium metabisulfite, sodium periodate, urea, and polyamidoamine-epichlorohydrin (PAE) improve the wet bond strength, but the surfactants CTAB and SDS at low concentrations do not. Although the high protein content of the ovalbumin is important for good strength, the low viscosity of the protein adhesive provides further insight into protein-protein interactions.