Manufacturers of chemical stains recommend that all acid stain residues be neutralized and completely removed prior to further treatment of the concrete.
A solution of baking soda (sodium bicarbonate) and water (approx. 1 lb. of baking soda per five gallons of water) can be used to neutralize the stain. The solution should be applied until it stops fizzing. After neutralization is complete, the surface should be rinsed thoroughly with clean water several times to remove all remaining residue.
NOTE: Runoff may stain adjacent areas or harm plants. Runoff should be collected by wet vacuuming or absorbed with an inert material. All stain residue, runoff liquid, rinse water, and absorbent materials used during application must be collected and disposed of in accordance with local, state, and federal regulations.
After rinsing is complete, a pH test should be performed on the surface to verify that no residual acid is present. If the color indicates a pH of 7 or higher, no residual acid is present. If color indicates a pH lower than 7, further neutralization is required.
Once pH is 7 or higher, allow the concrete to dry another 3-7 days before applying Liqui-Hard.