tannin blocking primer

How to Remove Tannin Stains from Wood Siding & Decks Short version: If you correctly diagnose whether you’re seeing true tannin bleed or an iron–tannin reaction, and you pair that with oxalic acid, proper neutralization/rinsing, and patient drying (48–72 hours, ≤15% MC) before priming, you’ll stop the stains and keep them from coming back. Below […]