How to Remove Semi-Transparent Concrete Stains
Semi-transparent stain is a chemical concrete colorant. It seeps into the porous surface of the concrete to color it, but still allows the texture of the concrete to show through the stain. If you want to paint or recolor your concrete, you will need to remove the existing stain. A chemical concrete stripper will open the pores of the concrete surface and remove the old semi-transparent stain.
Wait until the temperature is between 50 and 80 degrees Fahrenheit. Sweep the concrete surface to remove any dirt or debris. Spray any plants growing nearby with water so the chemicals will run off them if they come into contact.
Put on acid-resistant gloves and goggles. Stir the concrete stripper with a paint stirrer and pour it into a paint tray.
Paint a thick, even layer of the stripper onto the concrete with a paintbrush. Overlap each stroke so there is no missed section.
Let the stripper sit for one to six hours, or however long the package directions recommend. The stain will visibly lift out of the concrete. If the stripper dries out during the lifting process, paint more onto the dry spot.
Use a pressure washer to remove the stripped stain and the stripper. Start at the top of the concrete surface and work down. Rinse the concrete two more times to ensure that all the stripper is gone.
Remove Stains From Concrete
Concrete floors and surfaces can stain easily because of the porous nature of the concrete. Wash the concrete with a mixture of 1 cup trisodium phosphate (TSP) per gallon of water. Cover the stain with fresh kitty litter for three days and sweep it away. Alternatively, cover the stain with dry concrete mix and clean it up with a wet mop. Apply enzymatic solution to the stain to dissolve away the staining substance. Rinse thoroughly with water. Remove rust stains using oxalic acid. Wear safety goggles and rubber gloves when working with oxalic acid. Use an old towel to blot away the excess soap. Also called sodium percarbonate, oxygenated bleach is commonly available as a deck-brightening agent. Repeat often to prevent further mold and mildew growth.