How to Clean Bricks

Washing Bricks with Soap and Salt

Vacuum or brush away any loose dirt. If your brick is dusty or dirty, use a scrub brush to scrub at any surface-level dirt or dust. If you have a vacuum cleaner handy, turn it on and use the brush attachment to blow away residual debris. If you don't brush away all of the dirt, don't worry. You'll be able to scrub away the rest as you wash the brick. Avoid wire brushes, which can leave metal scratches on the brick and cause rust or corrosion over time.

Spray the entire surface of the brick with water. Dry bricks absorb soap, which can cause them to crumble or discolor over time. To prevent this from happening, fill a spray bottle with water and mist the entire surface of the brick. If you're cleaning multiple bricks and are outdoors, you can hose the bricks down as an alternative. This will cause the brick to absorb the water first and keep it from becoming saturated with soap.

Create a paste mixture from dish soap and salt. Pour 1 c (8.3 imp fl oz; 8.0 fl oz) of dish soap and 1 c (8.3 imp fl oz; 8.0 fl oz) of salt in a bucket and mix thoroughly. The paste mixture should have a gritty, yet spreadable texture. If you're cleaning many bricks, you can mix a larger batch of the paste mixture using a 1:1 ratio of soap and salt. Do not mix other cleaning solvents with the paste mixture, as some combinations (like bleach and ammonia) can result in dangerous chemical interactions.

Apply the paste to the brick with a washcloth and let it sit for 10 minutes. Dip a washcloth in the paste mixture and spread it evenly over the surface of the brick. Leave the mixture to sit for about 10 minutes so it can soften the dirt and debris before scrubbing it off. The paste layer can be as thin or thick as you want, with its thickness depending on how dirty the brick is.

Scrub the brick's surface thoroughly with a brush. After 10 minutes, use a scrub brush to clean away the dirt in circular motions. For stubborn areas, use applied pressure to lift the dirt or stains from the brick. Again, avoid using wire brushes to clean bricks. If you cannot scrub off all of the dirt by scrubbing, you may need to use acid or a pressure washer to clean the brick.

Rinse the paste off of the brick with warm water. Leaving the paste mixture on the brick can cause corrosion over time. Once you've scrubbed off the dirt, dip a clean rag in warm water and wipe away any soap or dirt residue. After washing the paste off, dry the brick off with a towel or leave the brick to air dry in a warm area. If you're washing multiple bricks outside, you can hose them off instead.

Cleaning Deep Stains with Boric Acid

Lay down a drop cloth in a well-ventilated area. Boric acid is corrosive and can cause skin or respiratory irritation. Find a well-ventilated area, preferably outdoors, and spread out a drop cloth over anything that could become damaged by the acid. If you need to clean the brick indoors, choose a spot near open doors or windows.

Put on a pair of goggles and thick, rubber gloves. While handling boric acid, make sure to cover your eyes and any skin that will directly handle the cleaning agents. Wear goggles to protect your eyes and rubber gloves to protect your hands and forearms. Wear long-sleeved clothes, if possible, to protect as much of your skin as possible. If you have long hair, pull it back tightly in a bun or ponytail while cleaning with acid.

Spray the brick with water. Dry bricks can become saturated with acid and crumble or corrode over time. To avoid this, fill a spray bottle with water and spritz the brick's surface before applying the acid. If you don't have a spray bottle, dip a washcloth in water and wipe the surface of the brick. You can also hose the bricks down instead if you're cleaning multiple outside (like a brick wall, for instance).

Fill a bucket halfway with water, then add the boric acid. The concentrated acid's strength will determine how much acid you'll need for a diluted cleaning solution. Pour the water first instead of the boric acid to prevent burns from the acid splashing up while adding water. You can buy boric acid online or from most home improvement stores. Boric acid generally comes in dry, highly concentrated packages before they're mixed with water, so handle it carefully and check the directions for how much to add.

Scrub the brick after about 5 minutes. Let the acid soften the dirt or debris for about 5 minutes. Then, dip a plastic bristle brush in the acid and gently scrub the brick in circular motions, focusing on particularly dirty or stained areas. Avoid using wire brushes to scrub the brick, as the metallic residue can corrode it over time.

Wash the acid off with a washcloth. After scrubbing away the dirt, dip a second washcloth in water. Wipe away any acid or dirt residue with the washcloth until the brick is clean, then dry it off with a cloth or leave it to air dry. If you're cleaning the brick outdoors, you can also wash the acid off with a hose instead. Leave any remaining boric acid in the bucket and contact your local authorities for disposal instructions. You may need to dilute it with water before flushing it away ot deliver it to a disposal center.

Pressure Washing Bricks

Purchase or rent a pressure washer for deep stains. Pressure washers are useful for spraying away stubborn patches of dirt or stains. You can purchase pressure washers online or buy them from many home improvement stores. If you don't own a pressure washer, you can buy or rent one from some home improvement stores.

Spray the brick's surface with a pressure washer about 12–18 inches (30–46 cm) away. Standing about 12–18 inches (30–46 cm) away from the brick's surface, turn on the power washer and spray the surface of the brick. Work from the bottom of the brick upward to make sure you coat the entire surface. Spraying the brick before adding a cleaner will prevent it from absorbing any cleaners and corroding.

Apply a mild cleaner or dish soap to the surface of the brick. Dip a washcloth in dish soap or a mild home cleaner mixed with water, as directed by the packaging. Wipe the solution over the surface of the brick in gentle, circular motions, coating the entire brick in the cleaning solution. For deeper set stains, you can apply a mixture of boric acid and water instead. Make sure to wear goggles, gloves, and long-sleeved clothes and work in a well-ventilated location.

Rinse the brick after letting the cleaner sit for 5-10 minutes. Leave the cleaning solution on the brick to soften the dirt or stains for around 5-10 minutes. Then, stand about 12–18 inches (30–46 cm) away from the brick and rinse away the cleaner with the pressure washer from the bottom up. To prevent the cleaner from corroding the brick, make sure you rinse off the entire surface of the brick. If you're working on multiple bricks, you can rinse all of them at once from the bottom up.