To clean a garage floor, begin by removing debris from the surface with a scraper or shovel, scrub the floor with a degreasing cleaner and a brush, remove excess solution with a wet-dry vacuum, scrub the floor with a muriatic acid solution and a brush, and rinse the floor thoroughly with a hose. Multiple applications of the muriatic solution may be necessary to completely clean the floor. After it dries, the floor should be white and rough as sandpaper.
The muriatic acid solution consists of 12 ounces of acid dissolved in 1 gallon of water. Scrub an approximately 10-foot by 10-foot area thoroughly for about five to 10 minutes before moving to a new section of floor. When working with muriatic acid, wear rubber gloves, rubber boots, protective eyewear and a respirator, and keep the area well ventilated.
To remove oil and grease stains from a garage floor, cover the area with cat litter or sawdust and let it sit for at least a day. Sweep away the material, cover the spot with dry dishwasher detergent and let it sit for about 45 minutes. Pour boiling water on the area and scrub with a stiff-bristled brush or broom. Rinse the area thoroughly with a hose.
To remove rust stains from a cement surface, dissolve 1 ounce of trisodium phosphate in 1 gallon of hot water. Pour the solution onto the spot and let it sit for 10 to 15 minutes. Rinse the area thoroughly with a hose.