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Question:

What is the proper application method for dry-shake color hardener, and what are the advantages of using hardeners instead of integral color? Read more about integral color vs. color hardener.

Although color hardener must be applied by hand, the results are worth the effort.

Answer:

I get this question from time to time. While fairly basic, it addresses a bigger issue: Why do some stamped concrete contractors prefer integral color and stay away from using color hardener?

I am a big proponent of color hardener! Using color hardener produces a stronger, brighter, more durable concrete surface than using integral color alone. Still, contractors tend to avoid color hardener for two reasons. First, integral color is easier to use. No application is required, and there's no mess. Just order it from your ready-mix supplier, and you're done. Second, many contractors don't understand how color hardener works, and thus are afraid to use it. That's too bad, because using integral pigments limits your color options and puts you at the mercy of the ready-mix company in regard to color consistency.

Although properly applying color harder is a bit of an art form, you can take a lot of the guesswork out of the process by following these basic guidelines:

(1) Use the coverage rate recommended by the manufacturer. Coverage rates generally vary by color. Lighter hardeners typically require a heavier application to achieve full color saturation (about 3/4 to 1 pound per square foot) while darker color hardeners hide better so you often need to use less (about 1/2 to 3/4 pound per square foot).

(2) Apply color hardener while the concrete is plastic (wet) but most of the bleed water has dissipated. It's better to apply the hardener a bit early than to wait until the concrete is too hard.

(3) Allow enough "wet out" time for the proper amount of moisture to wick up from the concrete and be absorbed by the color hardener properly. This step, though one of the most critical, is often overlooked by new color hardener applicators. Give the hardener at least 7 to 10 minutes to wet out before trying to float it into the surface. Running a float across the surface too early will cause tearing.

(4) Use a wood or resin float to incorporate the color hardener into the concrete rather than a magnesium or aluminum float.

I encourage all stamped concrete applicators to become competent at applying color hardener. Using hardeners not only expands your color palette, but also reduces color-related callbacks and produces a better surface finish.

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Learn more about how to buy color hardeners.

Author Chris Sullivan, ConcreteNetwork.com technical expert and vice president of sales and marketing for ChemSystems Inc.


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