RicoRock® Acrylic Stains are semi-transparent acrylic stains that are specially formulated to bond to RicoRock precast products and other concrete surfaces. Thousands of artificial rock waterfalls have been colored using these products in the past 10 years. These are waterbased non-toxic stains that instantly give new concrete a weathered rock appearance. No special training or equipment is needed. Antique is a coffee colored brownish black and is used to make the rock look aged. The other colors must be dry but the rock surface should be wet when applying antique. Leave the color in the crevices and heavy textured areas but sponge off the excess color quickly or you will darken the entire rock area. Keeping the sponge clean is important; otherwise the color in the sponge is smeared over any surface it touches and it will leave a permanent shadowing.