How to Remove Black Stains on Concrete

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Use water and ammonia or methylene chloride to remove black stains from concrete.
Use water and ammonia or methylene chloride to remove black stains from concrete. (Image: Jupiterimages/Photos.com/Getty Images)

Black stains on concrete consist of layers of dirt and oil, chemicals, ink or other substances. The combination of substances become darker as layers of dirt accumulate on top of the stain. When removing a black stain from concrete, it is important to completely remove the stain’s multiple layers to keep new dirt and debris from reattaching to the stain’s top layer. A water-based solution is capable of removing a black stain from concrete without the expense of using a commercial solution.

Things You'll Need

  • Broom
  • Dust pan
  • Trash bag or can
  • Ammonia
  • Warm water
  • Bucket
  • Latex gloves
  • Soft bristle scrub brush or sponge
  • Old towel or shop towel
  • Mineral spirits
  • Cornstarch, corn meal or cat litter
  • Methylene chloride
  • Trisodium phosphate

Ammonia Solution

Sweep the concrete with a broom to remove any loose dust and dirt. Sweep the debris onto a dust pan and dispose of it in a trash bag or can.

Mix 1 cup of ammonia and 1/2 gallon of warm water in a bucket. Wear latex gloves to keep your hands dry. Stir the mixture with a soft-bristled scrub brush or sponge.

Apply the mixture to the black stain and let it stand for 5 minutes. Scrub the black stain vigorously with the brush or sponge to remove the top layer of the stain. Re-apply the mixture to the stain and continue scrubbing until the stain is gone.

Wet an old towel or shop towel with warm water from a sink. Wipe the area where the stain was thoroughly with the damp towel. Let the concrete air dry.

Mineral Spirits

Complete step 1 of the previous section.

Cover the black stain with mineral spirits, found at hardware, paint supply and home improvement stores, then cover the stain with cornstarch, corn meal or cat litter.

Let the mineral spirits and cornstarch, corn meal or cat litter mixture stand overnight. Sweep the mixture with a broom onto a dust pan and dispose of the debris in a trash bag or can.

Wet an old towel or shop towel with warm water from a sink. Wipe the area where the stain was thoroughly with the damp towel. Let the concrete air dry.

Methylene Chloride

Complete step 1 in the previous sections.

Cover the black stain with methylene chloride, found at hardware, chemical supply and home improvement stores. Let the methylene chloride stand on the stain for 2 minutes.

Scrub the stain vigorously to remove the top layer of the stain. Re-apply methylene chloride and continue scrubbing until the black stain is gone.

Wet an old towel or shop towel with warm water from a sink. Wipe the area where the stain was thoroughly with the damp towel. Let the concrete air dry.

Tips & Warnings

  • If ammonia is not available, use trisodium phosphate (TSP), found at hardware, chemical supply and home improvement stores, instead.

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