How To Clean Soot Off Brick: Professional Advice and Guidance

Brick and other stone surfaces can be highly porous and absorptive. Their irregular texture makes them prone to smoke damage and stuck-on soot residue that's tough to clean, and you'll often need specialized cleaning agents to produce the best results.

The process of cleaning soot can be time-consuming and, if you're not careful in your approach, may even cause irreversible damage from hard scrubbing, as raw brick can be delicate.

In this guide, we're sharing professional methods for cleaning soot from brick and other stone surfaces without causing unsightly damage.

How Does Soot Settle on Brick?

Soot can end up on brick or stone in a few common ways, such as:

• Brick fireplace and chimneys: Incomplete combustion of wood or other fuels produces soot, which can be deposited on interior and exterior fireplace brick.
• Outdoor fires: Soot from barbecues, bonfires or outdoor fire pits can settle on nearby brick surfaces.
• Candle burning: Burning candles indoors can produce soot and create a soot stain on nearby brick - especially if placed too close to the wall.
• Kitchen activities: In homes or restaurants with a brick wall, brick oven or wood stove, cooking activities can produce soot that settles on those same surfaces.
• Factories and power plants: Emissions from industrial processes, especially those that burn fossil fuels, can release particulate matter, including soot, into the air. This soot can travel and settle on buildings, including brick surfaces, particularly in urban or industrial areas.

The following methods can help remove soot particles to make the brick look new once again.

Steps for Cleaning Soot Off of Brick

Before beginning any cleaning process, it's essential to pre-test the cleaning solution in a small, inconspicuous area on the brick or stone. You can use a Q-tip or cotton ball to apply the solution and a hair dryer to quickly dry the area, allowing you to assess the cleaning results.

It's important to note that the cleaned area may look different once fully dry, so using a hair dryer to speed dry the test spot will help you evaluate whether the cleaning method is working effectively.

If the pre-test shows positive results, you can proceed with cleaning the rest of the area. If the alkaline method doesn't work, you may need to switch to an acidic method. The choice between these methods depends on the burned materials involved and their pH levels.

Method #1: Alkaline Cleaning

Some cleaners may cause etching on stone surfaces, which is why it's important to use a solution designed to cut through soot particles without causing damage.

1. Remove any loose soot with a HEPA vacuum and dusting brush.
2. Using a pump-up sprayer and an alkaline stone cleaner, like StoneTech® KlenzAll Cleaner, spray a 3' x 3' area.
3. Pro tip: Start at the bottom and work your way up. That way, soot will not drip downward and create new stains as you clean.
4. Using a nylon scrub brush, gently agitate the sprayed area.
5. Rinse with clean water.

Method #2: Acid Wash

Before choosing an acid wash approach, note that this soot removal method eliminates a microscopic layer of the brick/masonry facing, making it more susceptible to moisture.

WARNING: Never use muriatic acid on stone or masonry, as it will etch most stone/brick/masonry surfaces. Avoid uneven or prolonged contact because etching, uneven cleaning or streaking can result.

1. Prepare a diluted solution of your acid-based cleaner, such as StoneTech® Restore Acidic Cleaner.
2. Using a pump-up sprayer, spray a small area (no larger than 3' x 3') and immediately follow with light agitation using a nylon scrub brush.
3. Rinse well with clean water.

Advising Clients on Soot Prevention

Once you've removed the stubborn stains from interior or exterior brick and stone surfaces, there are a few recommendations or tips you can provide to clients - depending on their situation -- to prevent future soot buildup in the home or business:

• Use high-quality fuel: Advise clients to use well-seasoned hardwoods or high-quality manufactured logs in fireplaces and wood stoves, as poor-quality fuel tends to produce more soot.
• Install a chimney cap: Recommend installing a chimney cap to prevent debris and moisture from entering, which can contribute to soot buildup.
• Check for drafts: Suggest checking for proper drafting in the chimney, as poor drafts are a common cause of incomplete combustion in chimneys.
• Fireplace doors: Suggest installing glass fireplace doors to help contain soot and prevent it from escaping into the room and onto nearby brick surfaces.
• Fireplace inserts: Recommend using a fireplace insert, which can improve burning efficiency and reduce soot production.

As for light cleaning, home or business owners can often remove soot fairly easily if it's caught early enough. At-home maintenance cleaning and tips to share include:

• Mild detergent solution: For superficial soot, advise using a mixture of mild detergent and water with a soft-bristled brush to gently scrub the bricks.
• Baking soda paste: Suggest making a paste of baking soda and water as a non-toxic cleaning solution for minor soot stains.

Brush Up on Your Soot-Cleaning Skills

Superficial soot on brick is easy enough to clean with the right products and techniques. On the other hand, more severe cases of damage, such as during a fire and smoke restoration project, require a soot-cleaning acumen that extends beyond scrubbing to include working with claims adjusters and more.

For upcoming classes and to sign up, visit our restoration and abatement classes page. Our two-day IICRC Fire & Smoke Restoration Technician (FSRT) seminar is designed to help cleaners and restorers learn the ins and outs of restoring fire-damaged structures.