Will CLR Remove Rust Stains From Cement and Concrete Surfaces?

Short for Calcium Lime Rust, CLR is a household cleaning agent renowned for dissolving tough stains. It’s particularly famous for removing rust build-up in bathtubs, stainless steel, sinks, toilet bowl, and more. But can CLR remove rust stain from cement and concrete surfaces?

CLR will remove rust stain from cemented surfaces, but you should first do a spot test to check for adverse reactions. Never use CLR on colored, sealed, stamped, or sealed concrete surfaces. Since CLR is a calcium remover, there’s a risk of pulling pigment and discoloring the concrete.

As the name suggests, CLR is specially designed to remove calcium, lime, and rust stain from most susceptible surfaces. Such stains result from water build-up, and the mineral drips in water that causes unsightly stains in home appliances.

Cleaning rust from concrete with CLR.

Main Ingredients in CLR

CLR is an aqueous acidic solution that contains several acids but is classified as non-hazardous.

The main ingredients in CLR cleaning agent are:

  • Water
  • Lactic acid
  • Lauramine Oxide
  • Gluconic Acid
  • Tripropylene Glycol n-Butyl Ether
  • Colorants

Using CLR To Remove Rust Stains From Cement and Concrete Surfaces

Before using CLR to remove rust stains from a cement surface or object, it’s always advisable to conduct a spot test. Since CLR is an acidic cleaning agent, it tends to discolor concrete surfaces.

The spot test shows whether it is safe to use CLR to remove the stains on the cement surface or object.

CLR Spot Test

  1. Mix equal parts CLR and warm water in a properly ventilated area.
  2. Apply the solution to a small hidden area of the surface you intend to clean. Use a cloth, sponge, or brush to apply the CLR solution.
  3. Let the solution sit on the rust-stained concrete for two minutes.
  4. Rinse off the CLR solution with cold water after two minutes.
  5. Let the area dry completely, preferably overnight.

If the spot test shows no adverse effects on the cement and concrete surface, such as discoloration or change in texture, it’s safe to use CLR on that surface.

Cleaning Rust From Cement With CLR

  1. Mix equal parts water and CLR agent.
  2. Apply the dilute CLR solution generously on the rust-stained cement surface.
  3. Let the mixture sit for two minutes.
  4. Rinse thoroughly with clean cold water.
  5. Repeat the process if the stain persists.

It’s best if you never leave the CLR solution to sit on a rust-stained surface for more than two minutes. Due to its acid content, CLR tends to etch older tubs, sinks, and tiles.

Never use CLR as a cleaning agent on any coated, sealed, or painted surfaces since they will discolor.

Is CLR Safe?

Unlike some other rust removers, CLR is water-soluble, biodegradable, and non-toxic to human beings. All the chemicals used to constitute the CLR are derived from vegetables, and it doesn’t contain strong mineral acids, such as hydrochloric acid.

CLR is a safer alternative to the harsh cleaning agents laden with harmful products, such as bleach, phosphates, alcohol, and ammonia.

CLR Safety Precautions

While CLR doesn’t contain strong mineral acids, it’s still an aqueous acidic cleaning solution. CLR cleaning solution can irritate your skin, while prolonged exposure can lead to severe chemical burns.

Oral ingestion of CLR solution is hazardous to your health as it can cause oral burns, induce vomiting, and stomach upsets.

Related post: How to Remove Rust Stains From Concrete With a Pressure Washer


CLR, also known as Calcium, Lime, and Rust remover, is a tough cleaning agent. It strips the stains that result from calcium, lime, and rust deposits on various surfaces, including cement.

However, it’s advisable to carry out a spot test before using CLR to remove rust stains from cement and concrete surfaces. The acidic cleaner can discolor or alter the texture of a concrete surface.

It’s inadvisable to use a CLR solution on painted, sealed, and coated concrete surfaces or on concrete that’s less than a year old.

1 thought on “Will CLR Remove Rust Stains From Cement and Concrete Surfaces?”

  1. I messed up and left the CLR rust removal on my concrete floor too long and in a large area. It removed the top shiny part and left the area with a brown cast. Can I do something to restore the white concrete finish?


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