Only use a power washer as a last resort – if you have a crumbling brick problem, this will make it worse. Simply spraying outdoor brick with a hose now and then rinses away any dirt that gets spattered on the bricks from sprinklers or rain.
For removing normal dirt and grime, simply rinse with plain water and scrub with a stiff bristled brush. The dirt will rinse easily off the brick after a little scrubbing. For stubborn stains, add ½ cup of ammonia to a bucket of water and rinse well.
Removing Green Moss or Mold from Brick
If the brick is continually moist, it will almost always start growing a variety of molds and mosses. It is fairly easy to remedy.
Tools you will need:
- Plastic spatula
- Garden hose with pressure nozzle
- High pressure hose
- Chlorine bleach
- Spray bottle
- Soft bristle nylon brush (no wire brushes)
- Eye protection, rubber gloves
How to do it:
- Once a year use a garden hose, with a pressure nozzle, to remove as much moss as possible.
- Periodically scrape off the moss or mold with a non-metallic spatula.
- Mix one cup of bleach into a gallon of water.
- Apply the solution on a small sample area first, then wait a week to see if there are any unwanted color changes in the brick.
- If there are no unwanted color changes, thoroughly soak the bricks with water.
- Using a spray bottle or hose spray attachment, spray the bleach solution on the bricks while they are wet.
- Let it sit for a week, then thoroughly soak the bricks again with water.
- Remove the moss with the scrub brush.
- If this does not get all the moss, use a power washer to blast the rest off.
- Better results are obtained when the moss is actively growing, but you should be able to remove the stuff even in cold weather. Avoid tightly focusing the spray or using so high a pressure that you damage the brick; start low and work your way up, keeping the pressure well below 3,000 psi.
- Always rinse thoroughly with clean water.
Be sure to wear rubber gloves as you scrub, and don’t forget eye protection—scrubbing and spraying can splatter the bleach mixture toward your face.
How to Clean Cement off Brick
The easiest way to clean mortar or cement off of brick is with a chisel. If the brick has not yet been used in construction, you can also knock the cement or mortar off with another, damaged, brick. If the cement is actually embedded within the brick, you may have to resurface the brick to get it off.
How to Clean Rust off Brick
The strategy for rust stain removal is to remove the rust while not causing more staining or opening the surface of the brick and making it more susceptible to weather related damage. The only acid that will effectively remove rust is Oxalic acid, not muriatic acid, which is often recommended. Either may damage the brick and leave a stain – so test it on a small area first.
A favorable alternative to harsh acids is a liquid called “Klenztone”, made expressly for this purpose.
How to Remove Oil Stains from Brick
Oil stains can be removed with a simple paste:
- Mix one pound of trisodium phosphate and one gallon of water.
- Add enough powdered chalk to thicken the paste.
- Spread a 1/2″ thick layer of paste over the stain and let it dry.
- Remove the dried paste with a wooden scraper.
- Wash the surface with clear water.
Paint Removal from Brick
Every so often, there is a vogue for painting brick facades, something that was seen in this country as early as the late 1700’s and has rarely looked good. Removing that paint can be a maddening process. Sandblasting causes lasting damage to the beauty and integrity of brick and should never be used. Chemicals may be applied to remove chalk, calcium carbonate, and rust; chemicals must be spot tested in various concentrations. Too high of a concentration can etch the surface of the brick, damage window glass, or cause discoloration. Such procedures are best left to professionals.
Keep in mind, however, that some older brick houses were meant to be painted. They are constructed of rougher bricks, or seconds, and were designed to be painted to seal them from the elements. Often they were whitewashed, or painted with fanciful colors to mimic stone work. Such houses should be periodically repainted after doing the appropriate prep work. Use a paint that is formulated for masonry, usually 100% acrylic latex.
Fresh paint stains can be removed with a commercial paint remover or a solution of two pounds trisodium phosphate, available at paint and hardware stores, to one gallon of water. Apply the mixture to the stain and allow to dry. Remove with a wooden scraper and wire brush. Rinse with water. For older paint stains, you may need to use steel wool or a wire brush. Be sure to protect unstained areas from any chemicals you use.
Are there other ways of removing oil stains from bricks?
My brick has black covering one area. It looks to me as though it starts where the water comes off the gutting on the chimney. Could it be from my black roofing? If so, how do we cleaning it? How would a commercial degreaser work? Thanks for you help.
My grandson marked up our brick fireplace with sidewalk chalk. How do I safely remove it? (Have already used a brush – it’s too thick to remove; it just went into the surface)
I have a chimney that has natural color bricks. They have a dull white powdery look to them. Is there some kind of solution I can brush on the brick to brighten the original color of the brick?
I purchased Glaze ‘N Seal clear water-based multi-purpose sealer. I applied it on a few bricks and I didn’t see a big difference.
Will the bleach spray solution be harmful to plants?
To Ted says
Yes. Any bleach solution will damage plants or even kill them, even if the solution lands on surrounding soil.
I have a question. I washed white brick and used muriatic acid. After drying, a yellow brick stain occurred. Now what do I do with it? Thank you.
In one corner of the basement is mold, which is coming from an area that is collecting rain water. The mold is flaking the paint off and some of the brick as well. How should I go about killing the mold?
Thank you for your time.
Apply a mold remover, allow the area to soak and then scrub off the mold. I would suggest applying a sealant to the area to protect against future rain water. You can also try vinegar, however vinegar might not work on your specific type of mold.
Source: HowToCleanStuff.net – How to Remove Mold from Bricks
Source: BlackToxicMolds.com – Does Vivnegar Kill Mold
How do I remove oil-based spray paint from a brick wall?
This is the article that you need: How to Remove Spray Paint from Exterior Brick and Cement.
Someone Painted The Outside Walls says
How can I get green paint from my outside brickwork off? It doesn’t look nice at all. I’ve tried a wire bush, but no good. Thank you.
If the paint is spray paint, you can use the article: How to Remove Spray Paint from Exterior Brick and Cement. If the paint is regular wall paint, you will need to use a commercial paint remover or the trisodium phosphate recipe along with the wire brush. Apply the paint remover, let it dry, then use the wire brush to scrape off the paint.
My maize corobrik face brick had a lot of cement residue on them and the hardware store advised me to buy a cement removal chemical, which I used and now my bricks have turned green. Please help; how do I reverse or remove the green color?
The bricks on my garage wall have black stains on them. How would I try to remove this?
I just bought a house with what looks like years of built up red clay dirt from the ground and rain on the brick of the exterior. How do I get the stain out? I’ve tried powerwashing and a brick cleaning solution from Lowes. Nothing seem to work. As an alternative, would you recommend painting the brick?
Take a look at this article: How to Remove Georgia Red Clay Stains. It is written for removing laundry stains, but you can try applying the information to your situation. For example, one of the tips in that article says that ammonia works particularly well on removing these stains. Therefore, look online to see if you can safely use ammonia on brick, which you can: follow the steps in the Ammonia section of the article How to Clean Brick.
Also, there is a commercial red clay stain remover made for brick that you can get at Home Depot (I don’t see it being available on the Lowes website right now, but they might carry it too.)
We have just moved into a bungalow. Someone painted the pebble dash and paint as run onto the brick work. What can we use to get the paint off the brick work please?
Use either a commercial paint remover or trisodium phosphate solution, following the method described in the third paragraph of the Paint Removal from Brick section. Keep in mind that TSP is a hazardous chemical, and you should take precautions when working with is, such as by wearing rubber gloves. Since you only have a small amount of paint to remove, it would be better for you to use a commercial paint remover. One that works particularly well for brick is Wipe Out Porous Surface Graffiti Remover as described in the article How to Remove Spray Paint from Brick and Cement. (Yes, it does work on regular paint, not just spray paint.) Good luck!
I have an outside brick wall that is turning black from the weather. How can I clean it off?
The black color is likely either mold or mildew. If so, this is the article that you need: How to Remove Mold from Bricks.
Source: ASHI Reporter – Brick Stains: Identification & Prevention
I live in a terraced millworker’s cottage. The doorway is of local stone, a type of gritstone (silicaceous grit). In the past, someone struck their matches on the doorway, leaving very dark marks from the igniting match head. These marks could be as much as 30 years old. How can I remove them without too much damage to the stone work? Please can someone advise me?
Try using the methods in the article How to Clean a Brick Fireplace.
My hummingbird feeder drops when it is windy and leaves a black stain on the limestone brick on the front of the house. How do I get the stain off?
The black stains could be several things: water stains (darkening) from the moisture, mold stains, or sugar stains from the sugar in the hummingbird syrup. Water stains simply need time to dry out. Mold can be resolved with the general cleaning listed above using bleach, though it will likely return when more hummingbird syrup spills. Instead, you can use a commercial mold remover as described in the guide How to Remove Mold from Bricks and select a product that will also help to prevent its return, such as Concrobium Mold Control. If you think the stains are sugar stains, you can try using Nature’s Miracle Hard Floor Cleaner, which is an enzyme cleaner for hard surfaces that can be found in most per stores and some major supermarkets. Sugar stains are more likely to look a dark brown color, whereas mold will be a more black color. Good luck!
Our home has a brick exterior which was treated with a slurry. Only the bricks were treated and not the grout. We would like to repaint the exterior, but are not sure if the slurry needs to be removed first. The slurry is not thick, it actually looks like someone just painted each brick white. Suggestions on where to start?
A great place to start would be the Brick Industry Association – there is a phone number on their website you can call. In general, slurry is considered permanent because the removal process is so involved and can potentially damage the brick; the removal process usually consists of applying muriatic acid to the slurry (mortar is very alkaline so it will react with the acid) and then scraping/brushing off the slurry. Powerwashing should not remove the slurry unless it’s very fresh, and sandblasting can damage the brick so that is not advised. However, before painting the surface, it should be powerwashed to ensure the surface is very clean, which will allow the paint to adhere better. The brick must be given enough time to fully dry out before painting though (at least 2 full days). When painting brick, it is important to use a breathable paint so that the brick can continue to breathe as well. Also, don’t forget to contact your HOA if you have one to get approval first as removing paint from brick can be very difficult as well. Good luck!
Source: Brick Restoration Inc. – Decorative Wash: The Complete Guide
Source- Ask the Builder – Brick Mortar Clean Up
Source: Bob Vila – All You Need to Know About German Smear
Source: House-Painting-Info – Preparing Brick and Masonry for Painting and Repainting