Tannin Wood Staining
Tanning wood staining: Brownish discoloration that will come through prime/finish coats unless properly primed.
Wood 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 1 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 top coats without proper priming. Select a top quality exterior paint in the color and sheen of your choice.