How to remove efflorescence stains from brick

Efflorescence, that white stain that appears on brick, is caused as salt and lime dissolve in the water in the brick, particularly in new bricks. Here is how to remove efflorescence stains from brick.

Moisture leaches out of the brick and leaves a powdery, white stain on the surface. Efflorescence occurs over time and the extent of the stain will depend on the quality of the brick; the ratio of sand, cement and water; the types of soil and material used to make the bricks; and the geographic area.

How to remove efflorescence

To remove efflorescence stains from brick, start by scrubbing the stained area with water using a stiff brush. Then, if some stain residue remains, use a muriatic acid product designed to remove stains from brick.

Use a 1:10 solution (1/2 gallon of acid to 5 gallons of water) to remove the stains from dark colored brick. For lighter brick, use a mixture of 1:15 (¼ gallon of acid to 3¾ gallons of water).

Before you mix the acid, make sure put on protective clothing (a cheap rain suit will do the job), safety glasses and acid-proof gloves. Apply the acid with an inexpensive five-gallon sprayer. The acid will ruin the sprayer, and you’ll have to discard it after the job.

Prepare the area before you apply the acid by making sure all windows are closed and protect landscaping by covering with drop clothes or plastic. Setting a fan up to blow air along the wall will help to dissipate the fumes. Apply the acid and wait 20 minutes. Then spray the wall with a mixture of 1 cup household ammonia to 1 gallon of water to neutralize the acid.

Finish the wall by washing it using a garden hose.

Preventing efflorescence

Once the brick is stain free, here’s how to protect it from additional stain. After the wall has dried, which could take as long as three days, use a heavy-duty paint brush and apply two coats of Behr premium protector and waterproofer.

Allow the first coat to dry thoroughly before applying the second coat. The protector and waterproofer will prevent water from penetrating the brick, but does allow water to evaporate from within the brick.

Be sure you are well protected when using the muriatic acid. Keep a box of bicarbonate of soda handy to neutralize any spills.

Tools and materials

• scrub brush
• old clothing
• vinyl-coated coveralls
• acid-resistant gloves
• 5-gallon sprayer
• muriatic acid
• household ammonia
• hose
• protector and waterproofer product
• heavy-duty brush
• fan (optional)