Paint can ruin the appearance of a concrete wall, patio or driveway. Paint is meant to be permanent, yet removing it off a concrete surface is possible. Be prepared to put in a lot of time and elbow grease to take the paint off concrete. Small areas of unwanted paint are easier to remove, while a larger area will take a lot more work.
Prepare the area around the painted concrete. Cover all nearby windows with plastic sheeting. Remove outdoor furniture, potted plants, toys, or barbecue pits from the area. If the concrete is indoors, make sure you have adequate ventilation by opening doors and windows. Sweep the concrete removing any dirt or loose flakes of paint.
Soften the paint on the concrete with vegetable oil. Pour a generous amount of vegetable oil on the paint. Use a scrub brush and spread it around the paint. Allow the vegetable oil to soak into the painted concrete for 48 hours to soften it up. Make sure to block off the area with caution tape, so no one slips on the oil.
Use a high-pressure power washer that is at least 3,000 psi to spray off the paint. A pressure washer should only be used on outdoor painted concrete. Attach the hose to the sprayer as directed in the instructions. Make sure the on/off switch on the sprayer is in the off position before you turn on the hose faucet. Use the lowest setting on the power washer to chip away and weaken the paint first. Turn up to a higher setting if needed. Make side-to-side sweeps over the paint until you see the paint chipping off. Go back and spray areas of paint several times until it is clean.
Use a store bought paint stripper to remove any left over paint. Paint strippers contain chemicals that may be toxic to humans, animals and the environment. Wear protective clothing such as gloves, eye covering, and a face mask. If you are concerned about the environment and toxicity, look for a paint stripper that is soy-based. Whichever paint stripper you use, follow the directions carefully provided by the manufacturer.
Sprinkle dry trisodium phosphate (TSP) on the concrete as your last step in removing the residual paint. Use a scrub brush and a little water and scrub vigorously. Rinse the area with water.
Grind or sand blast the paint off the concrete as a last resort. Rent a cement grinder or sand blaster from a home supply store. Wear protective clothing and follow the instructions that come with the grinder or sand blaster. Be aware that cement grinding can leave swirls or circles on the concrete, and a sandblaster may leave holes in the concrete.
Use caution when removing paint off of concrete. A high-pressure power washer may weaken and destroy the concrete while removing the paint. Check the stability of the concrete before you use any harsh methods or chemicals to remove the paint. If the concrete is crumbly, and you do not wish to cause more damage, simply use a scrub brush to remove the paint with the vegetable oil, TSP, or soapy water. Make sure all heat sources such as furnaces and pilot lights are turned off before using any chemicals.