A common question we hear is how to clean stains from brickwork. Since it’s spring and you’re ready to work, we’re sharing tips on how to identify and clean stains on your exterior brick. It’s important to correctly identify the type of stain you are dealing with for two reasons. First, you want to ensure you are using the correct technique and cleaner for that stain and secondly, you may be able to prevent future stains.
You might be anxious to get started with sprucing up your outdoor space – but please remember, sometimes less is more. Harsh acids and power equipment can be dangerous and overkill for your stain issues. The last thing you want to do is damage your exterior or have unsafe chemicals around the house that you really do not need.
NAME THAT STAIN!
Mold, Mildew and Organic Growth
Mold and mildew stains are typically black or green and often occur on the northern walls of a home where there is little sun exposure. Use a solution of 3 parts water to 1 part household bleach. Sometimes, certain exterior walls are constantly in a damp condition, which encourages moss, algae or other organic growth. Try household bleach, ammonium sulfate or even weed killer to combat this – carefully following user directions.
General Soiling or Mud
Use a solution of 1/2 cup laundry detergent and 1/2 cup TSP (trisodium phosphate) in a gallon of warm water (TSP is available at paint and DIY stores). Baking soda will remove mud stains as well.
Hard water has high mineral content, which can settle on the surface of brick; when hard water evaporates, it leaves behind that stubborn white haze or droplet marks. Simply mix 1 cup of white vinegar with 1 gallon of water. Then, dip a stiff-bristled brush into the solution, scrub the stains and rinse the bricks with clean water. Plus, you can simply replace leaky faucets and connectors that spray every time you use the outdoor tap.
Efflorescence occurs when natural salt deposits are released by moisture leaching through brick and evaporating at the surface, leaving white, hazy salt stains. Saturating the stains with water can create more efflorescence, so we recommend dry cleaning. For really tough stains, vinegar can be an effective stain remover because it breaks down and dissolves the mineral deposits. Brush the efflorescence stains with a dry stiff-bristled brush to loosen and remove them.
Use an environmentally friendly paint stripper available at your local hardware store.
Smoke or Soot
Before cleaning, vacuum any dry soot before applying any solution. Use a chlorine-based cleanser and scrub with a bristle brush.
If normal household cleaning agents don’t do the trick, apply a solution of water and oxalic acid crystals (2 – 3 oz. per quart water). Rinse with a solution of 1 ½ oz. washing soda (sodium carbonate) per gallon water. Sodium Carbonate is available at swimming pool supply stores.
Oil, Tar, Grease and Crayon
Try using a spot remover or tar remover available at your local hardware store or automotive store. For heavy tar stains, you can mix the remover with kerosene to remove the tar, then water to remove the kerosene. For small oil stains, you can try a poultice using naphtha or triochloroethylene is quite effective.*
A FEW KEY REMINDERS
– When using any of these solutions allow some time for the chemicals to dwell.
– Scrub with a stiff bristle brush (never use a wire brush).
– Always pre‐test in an inconspicuous section of your wall first.
– Rinse all solutions and treatments thoroughly with water when finished.
– Before jumping to proprietary brick cleaners, try the common chemicals and household detergents you might already have available at home.
– Please be aware however, that some products referenced are poisonous or otherwise hazardous, so please use caution, read all label directions, and protect your eyes and skin from exposure.
If the methods about are ineffective, there are also proprietary cleaners available for virtually every type of stain, one such company is Prosoco. Keep in mind that these cleaners are specifically formulated for a given problem and are usually more aggressive than the solutions above. Generally speaking, these commercial cleaners are intended for use by building professionals.
Please feel free to contact us if you have questions about cleaning brick here: https://generalshale.com/contact/
* The Brick Industry Association https://www.gobrick.com/Technical-Notes