How to Stain a Sidewalk With Acid

Scrub your sidewalk to prepare the surface. Mix enough cleaning solution to scrub the entire sidewalk. Use 1 cup of trisodium phosphate for every 4 gallons of water. If your sidewalk is relatively small, use a scrub brush to scour away the dirt. If it is relatively large, use a push broom.

Rinse the sidewalk thoroughly and allow it to dry in the sun before staining it. Mix your acid stain according to the instructions on the packaging. Every stain is a bit different, but most brands suggest using equal parts of stain and water.

Fill a paint sprayer designed for use with acid stains with the prepared acid stain solution. Alternately, you can use a roller to apply the stain. If you use a roller, fill a clean paint tray with the acid stain solution.

Apply the stain with your sprayer or roller. If using a sprayer, set it to the finest mist setting available. Paint the stain onto the sidewalk in a thin, even coat. Allow the stain to dry according to the manufacturer's instructions. Some stains may take as many as 24 hours to completely dry.

Apply additional coats of stain until you reach the desired level of pigment saturation. Allow the sidewalk to dry completely between each coat.

Mix 1/2 pound of baking soda with 5 gallons of water. Apply this solution to the sidewalk with a cotton or microfiber mop. The baking soda will neutralize the residual acid, making the sidewalk safe to walk on. Rinse the sidewalk thoroughly and allow it to dry.

Apply a concrete floor sealer to protect the stain. You can use water-based or solvent-based sealers for this process, though solvent-based sealers are recommended for outdoor concrete surfaces. Read the label on the packaging for specific information on mixing and application instructions for your sealer.