Monday, March 11, 2013
Ask a Pro
I'm a contractor and I'm about to start doing concrete countertops. I'm considering using your products by recommendation. Will the cement mix change the colors of the concrete stain as I've heard?
It is true that acid stain is different colors on different slabs of concrete. Applying 1 color to 10 different slabs means 10 different versions of that color. That's the beauty of acid stain, but also why a test must be done for every piece of concrete every time. Especially when it comes to countertops, because the colors are formulated for standard grey concrete that's made from a batch plant and poured from a truck, for foundation slabs, flatwork like driveways, etc. When you do a countertop, the concrete and the mix it is, completely changes the entire ballgame. The stain is reacting chemically with what is present in the concrete mix. Which is why different mixes and batches of concrete create different versions of the stain colors. Changing the concrete mix changes the color reaction and final outcome. A major player especially in countertops and overlays is the portland cement used. As the colors are formulated for a natural grey then using grey does help to an extent, however using a white portland would lighten the colors considerably. Darker browns would be lighter, blacks almost impossible as they would be turned into greys and/or browns.
The best advice I can give for countertops, is to make some sample boards of some different mixes to do some color tests and see how the different portlands and mixes and stains react together. Then you'll find some amazing combinations. You'll also learn which colors to use with which portlands/mixes to achieve the desired result. Regardless though, I would still make a sample board with every project pour to do color samples on, for the customer to approve, before staining the actual countertops. Because again, every batch you pour will still have different mineral content and random dispersion when you pour it.
I hope this helps