Things You'll Need
Stiff-bristle vinyl brush
Acid washing a tile shower safely removes grout haze and other hard-to-clean deposits, such as hard-water stains, from the grout and tile's surface. Grout haze forms on a tile's surface when the installer does not wash the excess grout, a Portland cement-based filler, off the tile's surface before the grout starts to dry. The acid wash eats the Portland cement film left on the tile. When properly used, acid wash will not etch a tile or damage grout.
Place a drop cloth on the bathroom floor near the shower. Turn on the bathroom exhaust fan or open the bathroom's window.
Fill a 5-gallon bucket with water and place a sponge in the bucket. Set the bucket of water on the floor outside the shower door.
Remove the shower's floor drain cover and water valve assembly, using the correct screwdriver to loosen the fixture's mounting screws. Set the removed pieces outside the shower.
Put on safety glasses and rubber gloves.
Combine the acid wash solution and water in a 1-gallon bucket, using the acid wash manufacturer's mixing ratio. Set the bucket in the shower.
Dip a stiff-bristle vinyl brush in the acid wash solution, soaking the bristles in the acid wash.
Press the brush against a shower tile wall and scrub the tile with the brush, using circular motions. Work from the top of the shower wall toward the floor. Repeatedly dip the brush in the acid solution. Do not let the acid wash solution dry on the tile.
Wash the acid wash solution off the tile wall with the sponge in the bucket of water. Rinse the sponge in the water after every pass across the shower tile.
Wash the tile on each additional shower wall with the acid wash solution, using the same method. Clean the acid solution off each wall's shower tile with the sponge. Work on one wall at a time.
Set the bucket of acid wash solution on the drop cloth covering the bathroom floor.
Scrub the shower floor tile with the acid wash solution, using the same method used on the tile-covered walls. Wash the acid wash from the shower floor with the sponge.
Empty the water in the 5-gallon bucket outside. Fill the 5-gallon bucket with clean water. Wash the shower tile a second time with the sponge and clean water. Replace the water valve assembly and drain cover.
Dispose of the acid wash solution, using the manufacturer's instructions. Often the manufacturer recommends diluting the acid solution in water and adding baking soda, then dumping the weakened solution down the shower drain.
Never dump the excess acid wash solution on the ground. Clean accidental acid wash spills immediately.