How to Remove Stains From Concrete

Concrete stains caused by oils, adhesives, rust and pigmented substances are stubborn. Act fast. The best way to fight a stain is to remove the material before it soaks into porous concrete surfaces. Use absorbent materials like terrycloth and paper towels or spill absorbers to soak up potential stains. Sawdust and cat litter can also be effective.

Sweep up and remove any dirt or debris around the area with a concrete brush or broom. These materials can hold moisture, inhibit cleaners and even trigger chemical reactions that worsen stains during stain removal.

After you clean up as much of the spill as you can and remove any debris, cover the stain with absorbent material. Let it sit for 24 hours. Then, sweep it all up. The absorber will soak up most of the staining material before it seeps deeper into the concrete, making clean ups less demanding.

Pro Tip: Never let water sit on a stain. Sitting water carries stains deeper into concrete surfaces. Stop this process before it starts.

Match the cleaner to the stain. Chemical cleaners are designed to target specific types of stains. Choose the right one for the job to set yourself up for faster, more effective stain removals. Follow all mixing, application and safety directions, and wear the appropriate personal protection equipment (PPE).

To clean oils from concrete, use detergents, degreasers or solvents. Recent advancements have also made microorganism-based cleaners more readily available.

Paint thinners, strippers and specialized detergents are widely used to remove paint from concrete. Trisodium phosphate (or TSP) can be used for more demanding paint stains. Use TSP with caution as it is toxic and requires proper personal protective equipment.

Remove adhesives and glues, including carpet glue, with sharp scrapers and hot water. Adhesive removers also work well and are most effective when used after scraping and treating with hot water.

Loosen most mastics with hot water mixed with vinegar and citrus-based cleaners. Let the cleaner soak up to an hour until the mastic loosens. Use a scraper or hammer and chisel to remove the mastic.

Effectively remove rust stains on concrete with common dish soaps, mixtures of lemon juice and vinegar, calcium, lime and rust removers as well as water displacing lubricants, like WD-40®. Allow these to soak into the rust stain for at least 10 minutes before scrubbing.

Pro Tip: Always test your cleaner on a small, out-of-sight portion of the surface before larger application. Variations in conditions and the concrete surface can leave you with an even more unsightly stain if not properly tested.

Concrete stains are persistent. Older, deeper stains can be particularly difficult, even returning after removal as buried pigments resurface. These returning spots will spoil look of finished concrete.

Always clean your treated surface thoroughly after stain removal. Rinse with water, squeegee and wet-dry mop after each process. This removes debris and makes it easier to identify missed or deeper, residual stains. If outdoors, use a pressure washer. Repeat your removal and cleaning process until residual stains are completely treated.

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