How to Remove Rust Stains from Concrete

  • June 27, 2019
  • / By Dale Keese
Rusty Concrete Wall

When you lay down new concrete or want to take protective measures against old concrete surfaces, you need to ensure the area is clean and ready for a new layer of sealer. Concrete sealer is important for you to prevent moisture from getting into the surface and also protect it from other hardships of weather. Before you put in a layer of sealer, however, you will need to clean out all rust stains from the concrete so it does not solidify under the sealer and become hard to remove later. Here are some common ways of removing rust stains on concrete.

Concrete wall with rust stain

Removing Rust with Acids

Most rust stains require some kind of acidic cleaner to remove or at least loosen the rust. The acid helps to lift the stain and scrub it away. Most acids remove rust (a form of oxide) by converting it into an oxide that can be dissolved in water. The following are some do-it-yourself (DIY) treatments you can use to remove rust stains from the concrete.

Lemon Juice to Remove Rust Stain from Concrete

For lighter stains, simple lemon juice is as good as any cleaner. The near concentrated form of citric acid is great for removing stains. Squeeze the juice of lemon all over the stain you want to remove. It would be more convenient to simply use store bought lemon concentrate instead of squeezing lemon by lemon on to the concerned surface. Let the citric concentrate sit for a bit and soak in the rust. After about 10 minutes, scrub the area off with a wire brush. Rinse it out to see how much of the area has been cleared out. If needed, repeat the process.

Lemon rust stain remover

White Vinegar Rust Removal

If you are dealing with slightly tougher stains, white vinegar instead of lemon juice may work better. Pour the simple white vinegar on top of the stained area and let it set. Once the vinegar has set, use a brush to scrub the stain out. You can also mix the vinegar with salt to increase the potency of the acid.

Carbonated Drinks Removing Stains from Concrete

Carbonated drinks can remove stains

Carbonated drinks like Coca-Cola, Pepsi, and others like it have an average pH of 3.4, which means they are leaning towards acidic. The carbon mixed with the acid makes simple carbonated drinks quite effective as rust removers as they can dissolve metal oxides. Pour the drink over the rusted area and let it sit for a bit. Then either scrub the area out or use a power hose to rinse the area since the sugar in the product may make it sticky.

Hydrochloric Acid Rust Stain Remover

If the stain is extremely tough and you have not had any luck with DIY home-based remedies , you can try hydrochloric acid but this requires the utmost care. Do not handle the acid without proper tools, such as a mask and gloves. You may also want to dilute the acid slightly. This process requires you to act quickly as if it’s left too long, the acid can stain the concrete surface blue. Always add acid to the water and not the other way round.

Let the water and acid solution sit on the stain for about 10 minutes, scrub immediately and then use a hose to wash the area out.  This potent rust remover should now have the stain removed.

Alkaline Stain Removers

While bases do not necessarily remove rust stains, there are some mild bases that have other useful elements that serve as cleaning agents.

Baking Soda

Baking soda rust stain remover

Baking soda is a mild base but is also an abrasive element. Baking soda is known to bubble and fizz when it reacts with certain elements. This is why it is used in cakes and baking so the crust can rise and be fluffy. The chemical reaction triggered by baking soda cuts the bond between the rust and the metal, making it easier to remove the oxidized portions.

For this DIY project, you will need to mix the baking soda with water to make a paste so it sticks to the surface. It is important to get the consistency right. The paste needs to be thick enough so it does not become runny but also not too grainy.

Laundry Detergent

Laundry detergent can also be an effective way to clean light rust stains from concrete. Make a paste out of laundry detergent and water and apply it to the area. If the detergent contains baking soda, even better. Make a paste thick enough that it does not run but it should not be so crusty that it dries off too fast. Keep the DIY paste on the stain for about an hour before scrubbing it off with a stiff brush.

Why Is Your Concrete Getting Rust Stains?

If you are noticing rust stains on your concrete more often than they should appear, check the source of your water. Often when water is derived from an underground well, the iron content in the water can be high. This iron-rich water is what could be staining not only your concrete but any surface it may be touching, including your clothes. 

Wall needing rust removal

Use a concrete sealer to prevent the damage to the surface. You should also avoid placing any metal furniture or objects directly on the concrete. You may want to check all your pipes for any possible leaks that may be exposing your concrete surface to excess water. Constant exposure to moisture can do a whole lot of damage to concrete surfaces. The sooner you catch the leak, the better.

Something you need to keep in mind while laying the concrete is that the bars supporting the concrete are non-corroding. When water seeps through the concrete, the metal begins to corrode, causing the rust to emerge from within the concrete. If the metal is non-corrosive, this problem can be nipped in the bud.

Final Thoughts

Having rust stains on your concrete floor can look extremely unappealing. But getting rid of the stain is not hard, provided you act fast and smartly. Most stains can be tackled with home remedies. If nothing else, there are more than enough industrial cleaners available in the market to remove such stains.

However, always be careful to wear protective tools, like gloves and masks, when dealing with acid-based cleaners like hydrochloric acid. So follow these simple DIY remedies toget the stain out and have your concrete look as good as new!