Dry-shake color hardeners come as powders that are hand broadcast onto the freshly placed concrete and then worked into the surface with a float or trowel.  Unlike integral pigments, which color the entire concrete matrix, hardeners color only the top surface layer. Because the color is concentrated at the surface, it tends to be more intense than integral color.

Most shake-on color hardeners are a blend of pigments, finely graded silica sand, wetting agents, and portland cement.  Coloring options come in a wider array of hues than integral liquid colors, including various shades of blue and green.  As the name implies, color hardeners also densify the concrete surface because they contain hard mineral aggregates and portland cement.  The result is a surface that’s stronger, more wear resistant, and less permeable to moisture and deicing chemicals than standard concrete.

One of the drawbacks, however, of using a color hardener is that if the slab is chipped deeper than 1/8″ it is likely that the gray concrete below will be exposed.