Tannin Stain Inhibitors
The advent of water-based resins for the architectural market have paved the way for new challenges associated with coating wood substrates. Wood is prone to rotting, warping, cracking, peeling and growing microorganisms. Oil and water soluble wood extracts such as tannic acids are a problem for water-based paints. Customers applying water-based paints to wood know firsthand that water brings ("bleeds") out the soluble stains to the topcoat and causes the paint to discolor and look unsightly. Tannin stain blocking additives were developed to augment resin technology in stopping the migration of these soluble stains to the surface of the paint. Blocking tannins and other common wood stains (sap, rosin, or other oleoresinous substances) can be quite daunting for water-based coatings. Tannin stain inhibitors come as white non-refractive pigments or as liquid additives which are formulated into paint where they are designed to react with soluble tannins to form insoluble complexes which do not migrate into the topcoat and cause discoloration. Tannins can be immobilized in the primer layer of a two-coat system or sealed in the wood substrate itself using appropriate sealers which can penetrate into the wood and form an impervious layer. Several technologies were developed to provide this chelation mechanism using multi-valent cations.
A low-cost tannin stain inhibiting pigment used in exterior architectural wood coatings.
A universal corrosion and tannin stain inhibiting pigment designed for architectural and protective coating systems and multi-substrate protection.