How To: Clean Brick
Say goodbye to grime on brick walls, fireplaces, and pavers with these safe, effective cleaning techniques.
The naturally distressed patina of brick adds to its desirability indoors and out, but too much dirt accumulation can reduce the beautifully weathered blocks—not to mention the mortar between them—to unattractively mottled masonry. Whether an exposed brick wall in your kitchen is covered in grease or your brick exterior is a mess of moss, you can undo the dinge and discoloration with the formulas and techniques shared here. You’ll have to prep the surface before going at the grime, but once you finish the task your brick will be restored to its former glory and you’ll once again be proud of the prominent place it has in your home.
How to Clean Brick Indoors
Take decorative accents off the walls and cover floors and furnishings in the vicinity with tarp or old newspaper to protect them from cleaning solvent splatter.
Remove loose dust and dirt from the brick surface using a vacuum cleaner with a brush attachment.
Dry brick readily absorbs cleaning solvents, causing it to fade or become discolored with unsightly white or greenish scum. To avoid this, enlist a spray bottle filled with water to saturate the dry brick before applying any cleaners.
Next up, continue with one of the following two methods: scrubbing the brick with dish soap and salt or scouring stains with boric acid.
- Dish soap and salt. The degreasing properties of dish soap, coupled with the abrasive qualities of salt, make for a powerful duo in combating stubborn dirt, grease, tar, and smoke stains on interior brick walls and fireplaces. Combine a cup each of dish soap and salt to form a gritty but spreadable paste. Use a clean dry rag to spread the paste in an even layer over a three-by-three-foot section of the brick surface. Then, working from the top to the bottom of the section, gently scrub the brick and mortar with a bristle brush (steer clear of wire brushes). Let the paste dwell on the brick for ten minutes, then remove the paste from the brick section with a clean rag saturated with warm water. Use a vacuum cleaner to siphon any lingering salt particles from the brick.
- Boric acid. The antifungal and antiseptic properties of boric acid help it expel stubborn stains that dish soap may leave behind. After donning rubber gloves and safety glasses, dilute a tablespoon of boric acid powder in a gallon of warm water in a large bucket. Dip a brush into the boric acid solution, then work the saturated brush into a three-by-three-foot section of the brick surface, using vigorous circular motions to scrub both the bricks and the mortar. Rinse away the boric acid solution from the brick section with a clean rag dipped in warm water.
How to Clean Brick Outdoors
Check the weather forecast: The optimal temperature to clean brick is 50 degrees or higher, preferably in cloudy conditions when cleaning solvents are less susceptible to drying quickly and leaving residue stains.
If needed, use a tarp to mask nearby metal, wood, and glass surfaces and cover lighting fixtures, windows, and plants near the brick to protect them from cleaning solvents.
Spray the dry brick down thoroughly with water from the garden hose.
When the brick dries, continue with one of the two following exterior solutions: bleach or muriatic acid.
- Bleach. Unsightly mold, mildew, and moss on exterior brick walls and pavers are no match for the stain-fighting and brightening properties of chlorine bleach. While wearing rubber gloves, combine a tablespoon of bleach with a gallon of warm water in a bucket. Apply the bleach solution with a sponge to a three-by-three-foot section of the brick. Then, enlist a bristle brush to scrub both the brick and mortar from the top down. If at any time the bleach solution begins to dry on the brick, spray a small amount of water over the brick with a hose to keep it moist. Finally, hose down the brick section with water to rinse away the bleach solution.
- Muriatic acid. When it comes to muriatic acid, an industrial-strength solvent, a little goes a long way to obliterate rust, soil, and mortar stains. Wearing full safety gear—rubber gloves, safety glasses, and a respirator—fill a large bucket with a gallon of warm water, then add one-and-a-half cups of muriatic acid. (Note: Always pour acid into water, not the reverse.) Dip a brush into the acid, then work the solution into a three-by-three-foot section of the brick surface using a bristle brush and a gentle scrubbing action. Let the acid dwell on the brick for a few minutes, then rinse it off completely with a hose and plain water.
Now that your brick surfaces are spic-and-span again, keep them that way by lightly spraying or hosing them down with water at least once a year, when they start to show signs of age.