Which Coloring Method is Better?
by Steve VandeWater
How does a potential customer choose between color hardener or integral color when deciding how to tint his concrete? Both options are acceptable, but each has its pros and cons.
Color hardener is a dry mixture made up of sand, cement, pigment, and slab conditioning agents. It is applied about 1/8 of an inch thick to the top of plain gray concrete just after it has been poured. The powdered color hardener is broadcast onto the surface, given time to absorb moisture, and is then floated into the concrete. When correctly applied, it actually strengthens the surface of the concrete by making it denser. A denser, harder surface can help the concrete to hold up better to traffic and weathering.
Aside from its hardening properties, another advantage to color hardener is that there are many hues available that cannot be readily obtained with integral color. For instance, if the customer wants a very light integrally colored concrete slab, one would need to substitute white portland cement for the gray cement normally used in concrete. This would not only dramatically increase the cost of the concrete, but would also decrease it’s set time. The finishing crew would have to work much more quickly to get the concrete finished before it hardened.
Because of the pigments used, some colors such as blues and greens are almost prohibitively expensive when using integral color. These same colors are more affordable with color hardener because much less pigment is needed to color only the surface of the slab.
The downsides to color hardener are that it is extremely dusty and messy, and that if the slab chips, the plain gray concrete underneath is exposed. Fortunately, chips can be easily patched with a slurry of color hardener and water.
Integral color is pigment mixed into the wet concrete in order to color it all the way through. Integral color is much easier to use than color hardener because it eliminates the steps of applying color and working it into the surface. Integral color allows a contractor to pour larger areas with less effort. In addition, since the colors are locked into the wet concrete, there is no colored airborne dust to deal with.
Customers often opt for integral color because they mistakenly believe that if their concrete is scarred or chipped, the chip will be unnoticeable. While it is true that the cement paste is colored, the rocks mixed with that paste are not. When concrete is chipped, there is usually a rock close to the surface which becomes exposed. The exposed rock is a drastically different color than the rest of the concrete, therefore the chip is still visible.
One downside to integral color is that it does not augment the surface strength of the concrete like color hardener can. Integrally colored concrete is simply the same strength as regular gray concrete.
Another downside to integral color is that chips and defects in the slab are much more difficult to patch. Patching materials usually need to be custom-tinted and experimented with to achieve a passable color match. To alleviate this problem, Butterfield Color in Aurora, Illinois makes patch materials that match each of their integral colors.
In summary, neither method of coloring is necessarily better than the other. They both have their good and bad points, and should be chosen based upon their merits, limitations, and the application for which they will be used.
Color charts for color hardeners and integral colors (in both liquid and powder forms) can be seen by clicking on the following links.