Removing Concrete Stains & Concrete Stain Removal
Concrete is a hard and durable building material. It is also porous and susceptible to staining. Painting or sealing a concrete surface is a good way to prevent staining. Unpainted or unsealed concrete can quickly become unsightly due to oil, grease, trees, birds or other agents. Often these stains can be removed easily.
The tannins found in tree sap, leaves and nut husks have been used as a natural stain for wood and yarn for years. They can also stain concrete. Oil and grease are common culprits.
Each type of stain has its own challenges. Much of your success will depend on the severity of the stain. You may have to clean the area several times to get results. It also helps to act as quickly as possible after the stain occurs.
Clean large amounts of a fresh spill by covering the area with cat litter. The litter will absorb most of the material. Dispose of the used litter properly.
To remove remaining material or if the stain is old, it is advisable to always look for a cleaner specially formulated for cleaning concrete. If you are in a pinch, try one of these:
- Household bleach – Dilute as the directions indicate for cleaning. Let the solution sit on the stained area for several minutes, then scrub and rinse.
- Laundry or dishwashing detergent – Sprinkle dry detergent over the area. Let it sit for a few minutes and then scrub with hot water.
- Tri-sodium phosphate (TSP) – Dilute one cup in one gallon of hot water. Pour it on the area and let it sit for 15-20 minutes. Scrub with a stiff brush. Rinse off with hose and repeat if needed. TSP is also available in a phosphate-free version.
Always wear eye and skin protection when using cleaning chemicals.
Muriatic acid is not a stain remover or cleaner. The acid actually etches away the concrete itself, and sometimes the stain as well. You will need to scrub and rinse this chemical also. Follow the directions carefully and WEAR EYE AND SKIN PROTECTION. Since you will be removing the actual concrete, use muriatic acid only if you seal the driveway with masonry sealer afterwards. Remember that you will be altering the level of the surface if you remove a lot of material.
To avoid damaging concrete:
- If you use a pressure washer, make sure you have the right nozzle. A jet that is too concentrated can damage concrete.
- Use a nylon scrub brush, not wire.