Stain Identification & Removal Guide

Not all stains are created equal. The wrong cleaner or technique can make stains worse or damage surfaces. This guide helps you identify what you're dealing with so you can remove it effectively.

Green or Black Stains (Algae, Mold, Mildew)

What You're Seeing

Green, black, or brownish discoloration in shaded or damp areas. Common on roofs, under eaves, or north-facing walls.

Removal Method

Soft wash with algae killer or mild bleach. Spray chemical, let sit 24-48 hours, rinse gently. Prevention: Soft wash twice yearly or apply algae-resistant sealant.

Orange or Rust-Colored Stains

What You're Seeing

Rust-colored streaks or deposits. Often along cracks or near metal fixtures.

Removal Method

Apply rust remover (F9 BARC, Pro Restore 21), wait 20-30 min, pressure wash at 2500-3000 PSI. Prevention: Replace rusty fasteners or cover with stainless steel.

Tan or White Powdery Coating (Efflorescence)

What You're Seeing

Dull, powdery, chalky coating on brick, concrete, or stone. Often on newly sealed surfaces.

Removal Method

Light efflorescence: Dry brush, then rinse. Stubborn: Use efflorescence remover or white vinegar, let sit 30 min, scrub, rinse well. DO NOT SEAL until efflorescence is gone.

Yellow or Brown Stains (Tannins)

What You're Seeing

Yellow, orange, or brown discoloration. Often appears as drips from overhead (mulch, leaves, vegetation).

Removal Method

Tannin removers or mild bleach. Spray, let sit 15-30 min, pressure wash at 2500-3000 PSI. Prevention: Apply stain-resistant sealer. Create barrier between mulch and hardscape.

Oily or Greasy Stains (Oil, Grease)

What You're Seeing

Dark patches on driveways from vehicles or equipment. Won't rinse away with water alone.

Removal Method

Fresh stains: Apply degreaser, wait 15-30 min, pressure wash at 3000+ PSI. Old stains: Multiple treatments may be needed. Prevention: Seal driveway every 2-3 years.

Call (301) 519-9274 for stain removal questions.