Acid Stain 

      Concete acid stain is a water-based chemical that contains acid that penetrates the pores of concrete creating a chemical reaction that produces a very natural look with the concrete being permanently altered.  Acid stain is best for new concrete or an older well preserved surface.   The stain will react differently with different areas of the surface which gives a beautiful look, but any irregular surface issues, including past stains, oil or other chemicals will create a different look on those surfaces.