TANNIN WOOD STAINING
Brownish discoloration that will come through primer/finish coats unless properly primed.
TANNIN STAINING CAUSES
Tannin escaping moisture and primers that don't block staining. The brownish stains are likely to come from redwood, cedar, mahogany and knots without priming. Severe staining may require more than one primer coat. Staining is more visible on light colors.
TANNIN STAINING SOLUTIONS
Locate and correct moisture sources. Wash with a commercial grade bleach solution, rinse thoroughly and allow to dry 48 hours minimum. Severe staining needs 2 coats or more of a stain-blocking primer. Cedar and redwood always require a stain-blocking primer.
PRIMERS & EXTERIOR FINISHES
Priming is critical. Stain will bleed through multiple topcoats without proper priming. Select a top quality exterior paint in the color and sheen of your choice.