How & can I change acid stain color on my concrete mantle?

by Cindy Craig
(Walla Walla, WA)

Q. I had my fireplace mantle made of concrete, acid stained and sealed with an acrylic (water base?) by a contractor. I am very unhappy with the moderately dark greenish gray & doesn't go with the rest of fireplace. I would like to change the color to dark brown or possibly black. The contractor said he would fix it but has not followed through with his word. I have done a variety of home improvements..simple to hard and would like to do this myself. Can I do this and how? Thank You for your help!

A. There are two ways you can do this. The first is to use a tinted (brown or black) solvent based acrylic concrete sealer and re-seal over the existing sealed concrete. This will change the color but it will also make it a solid color and you won't have the stained effect. Sherwin Williams can tint their solvent based concrete sealer to almost any color you want.

The other way is to lightly grind the surface using a 4" grinder and diamond pads. This will be dusty even if you use a vacuum but is the best and fastest way to remove the existing sealer. After the sealer has been removed you can stain the concrete again either with acid stain or I would recommend a water based concrete stain.