Rust Stain Removal from Brick and Concrete

There are two types of acids commonly used to clean concrete and brickwork of rust:

Oxalic Acid

Oxalic Acid Material Safety Data Sheet – Read this before using!

Oxalic acid is a strong organic acid can be found in wood bleaches (powder), certain household cleaning agents such as ZUD, and products specifically formulated for rust.

WARNING: Oxalic acid is toxic – keep your pets and other people away from the area you’re cleaning, wear rubber gloves and goggles and have the garden hose ready to wash it off of anyone or anything that accidentally gets exposed to it.

Instructions:

1. Saturate the area to be cleaned with the oxalic acid solution. If the product you’re using is a powder, wet the area to be cleaned, apply the powder, and then saturate it with water taking care not to rinse away the powder.
2. Let it sit for 5-10 minutes.
3. Scrub the stained areas with a stiff brush.
4. Apply more oxalic acid solution and allow it to sit for another 5-10 minutes.
5. Scrub the area again.
6. Continue to repeat this process until the rust stains are gone, then rinse well.

Muriatic Acid (Diluted Hydrochloric Acid)

Hydrochloric Acid Material Safety Data Sheet – Read this before using!

Hydrochloric acid works by eating away the surface material, thus removing the rust along with some brick or concrete. It does remove concrete stains better than oxalic acid, but is very corrosive and toxic to humans, animals and plants. Use this only as a last resort.

WARNING: This stuff is deadly and can blind, burn, and even kill you if you’re careless. Even the mist produced during use can damage your lungs. If you use it put your pets inside, keep all people away from the area, wear goggles, gloves, a painters mask, and clothing that covers 100% of your skin. If you dilute it with water, ALWAYS pour the acid into the water, never the other way around. If you pour water into muriatic or hydrochloric acid, a chemical reaction can take place that causes the water to instantly boil and splatter the acid all over the place. Have your garden hose ready to go at a moments notice to clean away acid from anything it gets onto that it shouldn’t, and rinse your concrete or brickwork immediately once the rust stain has diminished. Be very careful!

Use hydrochloric acid only if you’ve tried oxalic acid first. If you’re uncomfortable shouldering the danger involved, hire a professional to do it for you.

Instructions:

1. Cordon off the area to be cleaned to make sure nobody will wander up and be exposed to the acid or it’s mist.
2. Put your pets inside.
3. Wear clothing that covers your entire body and leaves no skin exposed. Put on goggles, a painters mask, and heavy rubber gloves.
4. Get your garden hose ready to go at a moments notice so you can flood anyone or anything that gets accidentally exposed to the acid.
5. If you choose to dilute the acid with water, pour the acid slowly and carefully into COLD water – not the other way around. Pouring water into the acid will cause it to splatter acid all over you and the surrounding area! Be VERY careful.
6. Cover the rust stain with the solution and wait. Do not scrub.
7. The instant the stain is removed, you should neutralize the acid or it will continue to eat into your brick or concrete. Cover the area with an alkaline powder such as lime to neutralize any remaining acid, then flood the area with water from your hose until all of the acid has been rinsed away.

*If you or anyone else comes into contact with the acid, flush the contact area immediately with water. Continue doing do for at least 15 minutes straight and seek immediate medical attention. If it comes into contact with clothing, remove the effected clothing immediately and wash thoroughly before reuse.

*If you accidentally spill hydrochloric acid, it can be neutralized with an alkaline material such as lime – saturate the area and then cover it with an absorbent material such as sand or earth and place it in a chemical waste container .

*Do not re-use any containers that have been used to contain hydrochloric acid.

If you enjoyed reading this article, might as well read how to remove rust from Tile Grout.

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