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Use the following expert insights to decide if you'd be better off using color hardener, integral color or both.

WHY USE COLOR HARDENER INSTEAD OF INTEGRAL COLOR?

Expert Chris Sullivan shares about why he likes color hardeners and how to use them:

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.

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

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STAMPING WITH CONCRETE HARDENER OR INTEGRAL COLOR

Engineer and architectural concrete expert, Jeff Potvin breaks down the advantages and disadvantages of these coloring methods:

One old dilemma contractors go through is deciding what coloring method to use when stamping concrete. The common choices are color-hardener and integral color. Each method has its advantages and disadvantages. I will compare their costs, installation procedures and durability.

The technology color-hardener is based on has been used for years on industrial floor applications. In these applications it was decided that due to heavy traffic, the strength of the floor need only be at the surface. This was just a hardener comprised of cement and metallic aggregate. Color hardener evolved when the metallic aggregate was replaced by mineral aggregate and the addition of iron-oxide pigment combined with proprietary surfactants. Color-hardener is tossed or broadcasted over a concrete surface that is in a plastic state. The hardener wets up and is then floated into the surface with a wood or magnesium float. Before stamping the surface it is closed up or sealed with a steel trowel or Fresno.

The first advantage of color hardener is its durability. Color-hardener is a layer that can be up to 1/8" thick and have a compression strength up to 8,000 psi which is twice the strength of the concrete base. The surface is now stronger and more wear resistant than regular concrete, the surface is also less permeable, preventing the intrusion of water, salts and other stains.

The second advantage of color hardener is cost. The price range is anywhere from 15 to 40 cents a square foot depending on the color and its coverage rate. But we must also look at the labor cost of its application. It will usually take six man hours to spread color-hardner on approximately 500 square foot of concrete. These man hours are usually wasted while workers wait for the concrete to set up. In most cases, however, the labor cost can be justified.

The two major disadvantages of color hardener are the mess and surface crusting. The mess can be controlled by covering everything in the immediate area with plastic. Surface crusting occurs when you have a low relative humidity and windy conditions. In some cases this combination can be so severe that it will prevent the use of color-hardener. If you find yourself in these conditions, using evaporation retarders will slow the moisture loss of the concrete. This is not the only solution, but that's another article.

Integral color is a blend of synthetic iron-oxide pigment and surfactants or wetting agents. Integral color can be found in three forms, powder, liquid and granular. The most common types are powder and liquid. When either is mixed with cement at different loadings, you will achieve color through the thickness of the slab.

The two advantages of integral color are speed of placement and color mixed through the whole slab. When placing integral colored concrete, pay close attention to the amount of water used. It is also best to have the pigment added at the ready-mix plant. With these two things in mind, placing integral colored concrete is just like placing gray concrete. Having the color mixed through the slab allows the contractor to begin stamping sooner with fewer issues concerning surface crusting.

The first disadvantage of integral color is the colors that can be attained. Since white cement is not readily available, all the color formulations are based on gray. With gray cement as the base, lighter and brighter colors are much harder to achieve. Some colors cannot be achieved at all even if the maximum allowable pigment loading of 9.4 lbs per sack is used. Manufactures rarely go over 6 lbs.. The second disadvantage is that your surface strength is the same as the concrete. When the surface is stamped, it will have high spots that will tend to wear faster.

The cost of integral color will vary from 10 cents a square foot to a $1.00. These costs are based on a 4" slab with 6 sack mix. So, the cost of integral color can be an advantage or disadvantage.

Both color-hardener and integral color have their advantages and disadvantages. What a contractor may use could vary from job to job depending on the circumstances. The best is a combination of both, which adds to the cost, but achieves a better overall product.

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Jeff Potvin, a Civil Engineer and the owner of Architectural Concrete Consultants, has nearly fifteen years of experience in the architectural concrete industry. His experience includes stamped concrete, overlays, form-liners, acid stains, counter tops and coatings.

INTEGRAL COLOR VS. COLOR HARDENER

Weighing the OptionsWhen making side-by-side comparisons of integral colors and dry shakes, here are some additional factors to evaluate before making a decision:

Cost vs. labor savingsGenerally, integral color will cost more than a dry-shake hardener because you are coloring the entire concrete slab rather than just the surface. But a dry shake may not always be the most economical choice if you factor in the additional labor involved to apply it and work it into the surface. Also remember that when using lighter shades of color hardener, you will need to use more product to get good results.

Using accent colors of hardeners can produce surfaces that replicate the subtle color variations in natural stone. Brickform in Rancho Cucamonga, CA.

Desired color effectsIf you want a greater selection of colors and more vibrant hues, then a color hardener will provide more options. With dry shakes, you can also apply accent colors of hardener to achieve contrast, using one shade as a base topped with as many as four or five different accent colors. Harris recommends using this technique on stamped concrete projects to replicate the subtle color variations you would see in natural stone.

Although it's possible to obtain more vibrant pastel shades with integral color, doing so could be cost prohibitive because you would need to use a white cement and a higher dosage of pigment. Another option is to use integral colors in conjunction with surface-applied treatments-such as color hardeners and chemical stains-to create layers of color.

If you can't find just the right color for your project, ask the manufacturer about the possibility of custom color matching. Suppliers of both integral color and color hardeners are often able to match existing color tones or formulate custom hues to suit your design scheme.

Creating SamplesClark Branum, director of technical services for Brickform Products advises that creating samples or mock-ups of the work to be done are critical to the success of any colored concrete application. "Mock ups with integral color are typically expensive since a minimum of 3 cubic yards must be used to produce consistent color, partially due to the amount of cement paste it takes to coat the drum of a cement mixer. With color hardener, it is much easier to create small panels and mock ups that can easily be reproduced on a larger scale, making it much more cost effective during the front end phase of a project," says Branum.

Jobsite considerationsDry-shake hardeners are not only labor-intensive, they also are messy to apply. Because some of the material goes airborne during broadcasting, it's necessary to protect adjacent buildings, landscaping, and existing slabs with plastic sheeting. This airborne powder can also be harmful to breathe, so it's important to wear a respirator or dust mask when working with these products. These issues aren't concerns when using integral color, since the pigments are mixed right into the concrete.

When applying dry-shake hardeners on extremely hot or windy days, you will also need to take measures to prevent moisture in the surface from evaporating too fast. Not only can this rapid moisture loss lead to surface crusting and cracking, it will make it impossible for you to properly wet out the color hardener. However, you can use an evaporation reducer, such as ConFilm from Degussa Admixtures and Eucobar from Euclid Chemical, to help slow surface moisture loss on hot, windy days.

PerformanceBecause color hardeners improve the strength and density of the concrete surface, they often are a good choice for exterior slabs exposed to freeze/thaw cycles and deicing salts and for interior floors exposed to heavy traffic and abrasion.

Integrally colored concrete will have the same surface strength as standard concrete, but the color is permanent because it penetrates the entire slab. So even if surface abrasion occurs, the color will not wear away.

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