With stamping mats and skins, you can achieve the look and feel of brick, slate, stone, and other materials with rough textures. However, to achieve the effect, you will need to replicate the natural colors of such materials. Contractors usually use four options to color stamped concrete. Most of the time, a dry-shake hardener or an integral color is achieved using a base color. When it comes to a variegated and a more natural look, accent or antiquing colors is used. It is achieved by using pigmented liquid or powdered release agents which are usually supplemented by tints, dyes, or stains.
– Integral Color
Advantages: It is easy to use. It comes mixed from the concrete batch plant thus providing a uniform, consistent color. It provides a permanent color as the concrete is composed entirely of it. The integral color will remain even if the slab is accidentally scratched or chipped.
Disadvantages: Compared to the look and feel that you can achieve with color hardeners, the color options are less vibrant and more subtle. This is why integral colors are mostly used with surface applied treatments, such as chemical stains and color hardeners.
– Dry-Shake Color Hardeners
Advantages: They come in an unlimited range of color options and produces brighter colors. Hardeners are usually scattered onto a fresh concrete and made to float on top of the surface. This product is less permeable because it contains cement and fine aggregate that cause the surface to densify.
Disadvantages: Because the product needs to be hand-broadcast, it is more labor intensive. Although hardeners are only applied on the top 1/8 to 3/16 inch of the slab which results in savings on cost, if the surface is damaged deeper than those levels, the underlying plain gray concrete will be revealed.
– Powdered or Liquid Release Agents
Advantages: Powdered or liquid release agents prevent the stamping mats from spoiling the texture of the concrete and from sticking to it. You can also achieve an antiquing effect because their properties bestow a subtle color that enhances dry-shake or integral color. The most commonly used technique is starting with a light base color with a hardener or integral color, and then applying a darker release agent for contrast.
Disadvantages: Nearby existing flatwork or existing buildings could easily get stained because the powdered release agents are airborne. They are very fine powders. Although powders require masking of adjacent surfaces and more clean up, they produce more contrast compared to a liquid release.
Advantages: Due to stains chemically reacting with the concrete (mottling effect), a sense of realism is achieved. Stains can be applied randomly to individual stones in your stamped design which is not possible to achieve with hardeners or integral color.
Disadvantages: Due to the natural coloring and transparency stains produce, they are mostly used together with dyes to achieve greater color intensity.
You can read more about the stamped concrete coloring processes at http://www.aaaconcreting.com/stamped-concrete/.