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

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

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If you left some hard water sitting on your concrete, or maybe some metal objects, chances are that you now have some rust on your concrete garage, patio, or driveway.

If you are looking for an effective way to remove that rust from the concrete, you might consider using muriatic acid. Today, we want to figure out what this substance is, how it removes rust from concrete, what its pros and cons are, and how to use it.

What Is Muriatic Acid and Will It Remove Rust Stains From Concrete?

Muriatic acid is an extremely powerful acid, one that is also commonly known as hydrochloric acid or HCl. It may also be referred to as spirits of salt, with muriatic loosely translating to “pertaining to salt”. This type of acid is commonly available in building and home supply stores, as it does have many uses.

It can be used for leather processing, descaling, household cleaning, steel pickling, pH control in water, table salt purification, and sometimes even as a food additive too. One thing to take note of is that muriatic acid is usually not pure hydrochloric acid, but rather a diluted version, usually around 29% HCI, with the rest being water.

Something that we will cover further below has to do with safety concerns, as this substance is quite dangerous. However, when it comes down to it, the answer to the question of the day is that yes, muriatic acid will remove rust stains from concrete.

Is Using Muriatic Acid the Best Way to Remove Rust From Concrete?

This acid certainly makes for one of the best options as far as the ability to remove rust from concrete goes. It’s a very powerful acid that has the ability to very quickly dissolve rust on virtually any surface including concrete.

It is also ideal because it will penetrate deep down into the porous concrete to remove any and all rust present. What can also be said about muriatic acid is that it’s very affordable, so you won’t have to pay much money for it.

That said, this substance does come with some drawbacks that may make you think twice about using it, mainly in relation to safety and concrete staining, both of which we will cover below.

There are also other great concrete rust removers out there, including lemon juice, vinegar, baking soda, CLR, WD-40, dedicated rust removers, oxalic acid, and trisodium phosphate.

Pros of Using Muriatic Acid for Removing Rust From Concrete

Let’s take a look at the pros of using muriatic acid to remove rust from concrete.

1. It’s Cheap

One of the biggest benefits when using this substance for rust removal is that it is much cheaper than many other acids and professional rust removers. You can buy a whole bottle of muriatic acid for just a few dollars.

2. It’s Fast

Another reason many people prefer using this acid for rust removal is that it is a very powerful acid and therefore works very fast at dissolving rust from a variety of surfaces. It only takes around ten minutes of soaking on the concrete for the rust to be totally dissolved.

3. It’s Effective

Moreover, muriatic acid is not only very fast-acting in this sense, but also very effective. By this, we mean that this substance has the ability to penetrate deep down into the rust and into the porous concrete, therefore removing all rust. Remember, concrete isn’t very smooth, so you need something with the power to penetrate the surface.

Cons of Using Muriatic Acid for Removing Rust From Concrete

Now that we know why muriatic acid is a good option for removing rust from concrete, let’s take a look at some of the drawbacks it has.

1. It Can Melt Containers

When diluting muriatic acid, because it is so strong, be sure to use acid-resistant containers such as glass. If we are talking about normal low-grade plastic, this substance can actually melt it.

2. It’s Very Hazardous

What you also need to know about muriatic or hydrochloric acid is that it is very dangerous. It’s super corrosive and can cause severe chemical burns on your skin. It can also burn or severely damage your eyes and other mucus membranes. Additionally, it’s very hazardous to inhale and should therefore only be used with a fume hood or in a well-ventilated area. Although effective for rust removal, it’s not safe in the least.

3. It May Stain Concrete

You should always do a spot test first, as this substance may in itself stain or discolor the very same concrete that you are trying to rid of rust stains.

How to Remove Rust From Concrete with Muriatic Acid

Let’s go through a quick step-by-step process on how to remove rust from concrete using muriatic acid.

Step 1: Dilute the Acid

Muriatic acid is very strong and should not be used as is. You first need to get an acid-resistant container and mix one part acid with ten parts water.

Step 2: Do a Spot Test

To make sure that your acid solution does not damage the concrete, do a small spot test in an area that is out of sight. If the concrete is not stained once you wash the acid away after a few minutes, you can proceed.

Step 3: Apply the Acid

Generously apply the solution to the affected area and let it soak for ten minutes, but no longer, or else it may stain the concrete.

Step 4: Scrub

After the muriatic acid has soaked for eight or nine minutes, get a stiff bristle brush and scrub the affected area until the rust has been loosened.

Step 5: Rinse

Use cold water to rinse the acid away. You may need to repeat this process for very heavy buildups.

Mistakes to Avoid, Tips & Tricks

Let’s quickly go through some tips to help make this process as easy, fast, and safe as possible for you:

  • Always wear acid-resistant rubber gloves and proper eye protection when working with this acid.
  • Always wear a fume hood or a respirator when working with this acid, or be sure to work in a well-ventilated area.
  • Make sure that you have a plan for where the acid will go when you rinse it away. You don’t want to leave it on your driveway or sidewalk.


Although muriatic acid is quite dangerous to use, it is effective at removing rust from concrete. Just be sure to take the proper precautions when using it.