How to Clean Brick: The Complete Guide to Restoring Its Natural Charm

Few building materials bring the warmth, character, and timeless appeal that genuine brick offers. Whether it frames an exposed accent wall in your living room or creates a welcoming exterior facade, brick does more than support a home—it adds soul.

Over time, though, natural elements, soot, moisture, and dust take their toll. Weathered brick can quickly shift from rustic to tired. The secret to bringing it back to life lies in knowing how to treat it gently. Aggressive scrubbing or using the wrong chemicals can strip the mortar or permanently pit the clay face.

Here is your step-by-step guide to identifying what is dirtying your brick and choosing the right method to restore its natural beauty.

First Step: Identify What You Are Dealing With

Before grabbing a bucket and sponge, take a close look at the surface. Different stains require entirely different solutions:

• Green or black patches: Usually moss, algae, or mildew caused by trapped moisture and shade.
• Chalky white haze: Often efflorescence (mineral salts drawn out of the masonry by water).
• Hard, grey lumps: Leftover mortar or dried cement remnants from construction work.
• Dark, greasy smudges: Everyday soot, dirt, or pollution buildup.

Choosing your cleaning agent based on the specific problem ensures you get brilliant results without unnecessary surface wear.

1. How to Remove Mold and Mildew from Brick

Mold and mildew thrive on damp, shady brickwork. A straightforward bleach mixture will kill organic growth at its roots without eroding the brick.

• Mix your cleaning solution: In a clean bucket, combine equal parts household bleach and warm water.
• Prep your tools: Pour the diluted mixture into a standard garden pump sprayer for even, easy application.
• Rinse the wall first: Spray the section with fresh water using a garden hose to remove loose dust and keep the brick from absorbing the bleach too deeply.
• Apply from the top down: Pump and spray your bleach solution evenly across the brick, working downward so runoff cleans as it goes.
• Let it work: Allow the solution to sit on the surface for a few minutes. Keep an eye on it—do not let the chemical dry onto the brick.
• Test and scrub: Gently brush a small, inconspicuous patch using a stiff, acid-resistant nylon brush (avoid metal wire brushes, which leave rust marks). If the mildew lifts easily, scrub the remaining area.
• Rinse thoroughly: Wash away every trace of the bleach solution with a clean water rinse, then let the wall dry completely in the open air.

Safety tip: Always wear rubber gloves, eye protection, and old clothes when working with bleach.

2. Removing Stubborn Cement and Mortar Residue

Hardened cement splatters or dried mortar tags require an acid-based cleaner, such as diluted muriatic acid or specialized masonry restorer.

• Safety first: Work in a well-ventilated area, wear heavy rubber gloves, safety goggles, and a protective respirator.
• Dilute carefully: Fill a plastic bucket roughly two-thirds full with fresh water, then slowly add one-third volume of acid. Crucial rule: Always add acid to water, never water to acid, to prevent dangerous chemical splashing.
• Saturate the brick: Soak the problem area thoroughly with plain water before applying acid. Wet brick prevents the acid from burning into the clay core.
• Apply and gently scrub: Using an acid-resistant brush, work the diluted solution into the mortar splatters. You may hear a soft fizzing sound as the acid reacts with the alkaline cement.
• Time it carefully: Let the mixture sit for 10 to 15 minutes, but mist it lightly with water if it starts drying out. Never let acid dry on masonry.
• Rinse deeply: Flood the wall with plenty of clean water to neutralize and rinse away the acid residue.

3. Deep Cleaning with a Pressure Washer

For expansive exterior brick walls, patio pavers, or loose reclaim bricks covered in ground-in grime, a pressure washer saves hours of elbow grease.

• Gather your supplies: You will need a pressure washer (set to a low PSI, ideally between 500 and 1000 PSI to avoid gouging soft brick), a garden hose, an all-purpose exterior cleaner, and a stiff utility brush.
• Pre-soak the surface: Wet down the brickwork with plain water using the low-pressure nozzle.
• Apply your cleaner: Spray your mild cleaning detergent or diluted bleach solution across the surface and let it penetrate the grime for 5 to 10 minutes.
• Scrub heavy spots: Use your utility brush to agitate stubborn oil stains, soot, or heavy dirt pockets.
• Rinse under moderate pressure: Keep the pressure washer nozzle at least 12 inches away from the wall. Move in smooth, sweeping motions across the brick face, taking care not to point the high-pressure stream directly into aged mortar joints.

Keeping Your Brick Looking Fresh

Once your brick is clean, a little routine maintenance goes a long way. Periodically sweep off outdoor walls to stop organic debris from taking root, ensure your gutters are not overflowing onto the facade, and consider applying a breathable silane-siloxane sealer to repel future moisture and stains without trapping vapor inside.