Using muriatic acid to clean masonry surfaces is an effective and dangerous venture. Follow these steps to ensure the safety and effectiveness of your project.
Step 1: Scrub the surface clean with a stainless steel scouring pad or scrape clean with a sharp chisel. Use trisodium phosphate (TSP) to clean the area. Rinse thoroughly with water. Always use muriatic acid as the last resort.
Step 2: Only use muriatic acid in a well-ventilated area. An abundant supply of water, a respirator, goggle-type eye protection, chemical resistant gloves, rubber boots, pants and a long-sleeved shirt are non-negotiable accessories.
Step 3: Keep water and baking soda or garden lime nearby at all times. Acid spills can be neutralized by sprinkling with baking soda or lime and flushing the area with a large amount of water. If any acid comes in contact with skin, flush immediately with water.
Step 4: Thoroughly wet the area to be cleaned with hot water. Hot water increases the surface temperature and soaks into surface pours; improving the effectiveness of the acid wash and mitigating potential damage to the masonry.
Step 5: Use a 10:1 water to muriatic acid solution for most applications. Fill a plastic bucket with a gallon of water and slowly add 13 ounces or less of muriatic acid. Always add the acid to the water. Adding water to acid can cause an explosive reaction.
Step 6: Carefully brush or spray the acid solution onto the affected masonry. A plastic spray bottle or pump type garden sprayer work well for this.
Step 7: Allow the solution to set for a minute or two before using a stiff, natural bristle brush to scrub away residue. Flush the area with water as you scrub to reduce splashing. Repeat the process if necessary. Work in small sections until the masonry is clean.
Step 8: Rinse the surface thoroughly with a neutralizing solution of 1 cup ammonia to 1 gallon water. Flush with water and allow to dry.
Step 9: Neutralize remaining acid outside before disposing of it. Pour 3 cups of lime into the bottom of a 5-gallon bucket. Use a wooden stick to stir in 1 gallon of water. At arm’s length, with a respirator on, slowly add acid to the bucket. Stir gently until the solution stops fizzing. Add more acid and more lime until all acid is neutralized.