Cleaning & Sealing Flagstone Pool Decks: Acid Wash vs. Sealer

Acid wash flagstone only to remove mortar haze or mineral deposits—it etches stone, doesn't enhance color. For routine cleaning (dirt, mildew), use mild bleach and low-pressure wash. To enrich color and protect, apply a penetrating, oil-based masonry sealer with high solids (like Rez-Seal) in matte finish. Test first—sealers darken stone and can create slippery surfaces; add non-slip additive (Shark's Skin or silica sand) if needed.

Sealing reduces water absorption, freeze-thaw damage, and mold. Reapply every 2–3 years. Well-sealed stone in full sun gets hot—consider foot traffic patterns.