What are tannins in paint?

Tannin staining. Tannin Staining is the brownish or tan discoloration on a painted surface due to migration of tannins from the substrate through the paint film. Typically, this occurs on ‘tannin rich timbers, such as redwood, cedar and mahogany, or over painted knots in certain other types of timber.Click to see full answer. Keeping this in view, what is tannin blocking?Tannin Stain Inhibitors. 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.Likewise, what is wood tannin? Tannin. Tannin is responsible for the astringency, colour, and some of the flavour in tea. Tannins occur normally in the roots, wood, bark, leaves, and fruit of many plants, particularly in the bark of oak species and in sumac and myrobalan. They also occur in galls, pathological growths resulting from insect attacks. Also question is, how do you stop tannins from bleeding? Seal the stains with an alkyd/oil primer or a coating designed to trap these tannins. Note: Even with proper preparation and recommended products, tannin bleed can still occur, especially on new wood, with either latex or oil topcoats. To wash off the tannin stain, use SuperDeck® Revive® Deck and Siding Brightener.Why do stains bleed through paint?The quick fix is a sealer so the tannin or stain can’t penetrate through. Other stain blockers that also work are oil based primer/paints, spray shellac, polyurethane or even wax. By applying any of these products, the stain or bleed through will be sealed and won’t penetrate through your next coat of paint.