Will CLR Remove Rust from Concrete? (Yes & Here’s How)

Will CLR Remove Rust from Concrete? (Yes & Here’s How)

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If you have a nice concrete driveway or patio that you left some iron-rich metal sitting on for far too long, chances are that there are some rust stains present. Removing rust stains from concrete can be challenging unless you use the right cleaning agent.

Today, we want to talk about one specific cleaner, CLR, what it is, and whether or not it can remove rust from concrete.

What Is CLR and Will It Remove Rust Stains from Concrete?

CLR is a very popular cleaning product in North America, one that stands for Calcium Lime Rust. It consists of various ingredients and compounds including water, lactic acid, gluconic acid, lauramine oxide, propylene glycol, glycolic acid, sulfamic acid, citric acid, and several others.

The exact formulation will depend on the exact version of CLR being used. The acids contained in CLR have the power to dissolve calcium and rust without damaging the surrounding surfaces.

As the name of this product implies, it is designed to remove calcium, rust, and lime stains from a variety of surfaces, and yes, this includes concrete. If you have some minor to moderate rust stains on your concrete driveway or patio, it will work to remove rust stains.

Is Using CLR the Best Way to Remove Rust from Concrete?

Whether or not using CLR is the best way to remove rust from concrete is questionable. Now, keep in mind that there are actually quite a few different ways of removing rust from concrete, and CLR is just one of them.

Generally speaking, using a special concrete rust remover that is dedicated to this exact task will work best. There are also other less expensive and more eco-friendly methods than CLR, including baking soda and laundry detergent, vinegar and lemon juice, and others.

There are also other, more powerful options to consider, including hydrochloric acid and trisodium phosphate. That said, CLR works just fine for moderate rust stains, so you can use it without issue.

Pros of Using CLR for Removing Rust from Concrete

Let’s quickly take a look at the benefit that you get from using CLR for removing rust from concrete.

Step 1. It’s Fairly Eco-Friendly

We wouldn’t say that CLR is the number one most eco-friendly cleaner out there, but it has come a long way in the last couple of decades. CLR is designed to be non-toxic to humans, biodegradable, and water-soluble. The chemicals used in CLR are made from vegetables, and it is a safer alternative when compared to ammonia, bleach, and phosphates.

Step 2. It’s Fairly Affordable

CLR is a good option to consider simply because it is affordable. Depending on where you buy it, you won’t spend more than $10 for an average bottle, or around $1.14 per 100 ml. It certainly doesn’t cost very much.

Step 3. It Works Quite Fast

Although CLR might be mainly natural, the ingredients it contains work fairly fast at removing rust from concrete. It’s going to take less than 10 minutes for this solution to dissolve rust from concrete.

Step 4. It’s Pretty Powerful

As we stated above, CLR is quite powerful. It has the ability to remove some fairly tough rust stains from a variety of surfaces including concrete.

Cons of Using CLR for Removing Rust from Concrete

There are also some drawbacks to using CLR for removing rust from concrete, so let’s take a quick look.

1. Safety Issues

Keep in mind that ingesting CLR can cause stomach upset, vomiting, and oral burns, with prolonged exposure to the skin causing irritation and possible chemical burns.

2. Possible Staining

CLR may actually stain concrete itself, although you won’t really know until you try. Therefore, doing a spot test in an out-of-sight area to see whether or not it stains is recommended.

3. Can’t Be Used on All Concrete

You need to realize that CLR cannot be used on all concrete. You should not use it on concrete that is coated, sealed, or stamped, as well as on concrete that is tinted or colored, or on concrete that is less than one year old.

4. Concrete Contains Calcium

What you also need to realize is that concrete contains calcium, so using CLR, which dissolves calcium, will start to damage and break down the concrete, especially with regular application.

How to Remove Rust from Concrete with CLR

Now that you know both sides of using CLR for removing rust from concrete, let’s figure out how to do it.

1. Put on Safety Gear

To help avoid irritation, putting on rubber gloves to protect your hands, and safety goggles to protect your eyes is strongly recommended.

2. Do a Spot Test

Because CLR may stain concrete, doing a spot test is recommended. Choose a small part of the concrete that is relatively out of sight and apply a small amount of CLR. Let it sit for two minutes then wash it away. If no staining occurs, move on to the next step.

3. Apply the CLR and Let it Soak

You now simply have to apply the CLR to the affected area and let it soak for a few minutes. For moderate stains, let it soak for around two to five minutes and up to ten minutes for severe stains.

4. Scrub and Rinse

If the stain is severe, use a hard-bristled brush to scrub the area, then use cold water to rinse everything away. Repeat as necessary.

Mistakes to Avoid, Tips & Tricks

Let’s quickly go over some tips to help make this process easier and safer:

  • Don’t use CLR on coated, painted, stamped, or sealed concrete.
  • Try doing a spot test on a piece of concrete that you can’t see easily.
  • Never ingest CLR or touch it with your bare hands.
  • Don’t let the CLR sit on the concrete for more than ten minutes.


As you can see, using CLR to remove rust from concrete is fast, easy, and effective.