Concrete acid stain does apply to new or old, plain or colored concrete surfaces. They are available in 10 basic colors. But they are often called acid stains, acid is not the ingredient that colors the concrete. Metallic salts in the acidic, water based solution react with the concrete to permanently colour of the surface. Siliceous aggregates such as gravel or sand, usually do not react with the stain. Surfaces containing a greater content of cement will react several with less cement yielding more serious colors. _stained_concrete_
Since each surface differs from the others, results may vary derived from one of surface to another. We always recommend testing a small area to determine how the final result will appear. Be aware that the final color will never be apparent until the sealer has become applied. With wood stain you'll probably still see the grain in the wood through the stain, acid stain is extremely similar to wood stain as we discussed all defects or finishing marks through it.
Factors that may affect the final results include:
Cement properties and amount used, Admixtures and type of aggregate used.
Concrete finishing methods, concrete age, and moisture content
Porosity and Texture from the surface
Weather conditions in the event the stain is applied