Acrylic Concrete Stains

If you are considering expanding your painting skills into decorative concrete, acrylic stains are a good place to start. These water-based stains provide opportunities to create unique designs and detailed patterns that most painters do not get to work with in typical applications.

Professionals in the decorative concrete world use a variety of techniques to colorize their surfaces. Methods range from adding “integral color” pigments during the mixing process to texturing a surface for shadowing effects. Clearly, most of these processes aren’t tasks typical painters would take on themselves.

However, acrylic stains are in the painter’s realm. They are applied to a surface, often with brushes, rollers or sprayers. These products are gaining popularity in the concrete industry because they are some of the simplest to use.

Painters may find a business opportunity here if they are interested in work that involves more prep, more attention to technical detail, and even follow-up maintenance.

Acrylic stains can be used to create accents or glazing effects like faux marble or stone. Contractor and instructor Bob Harris, owner of Decorative Concrete Institute in Temple, Ga., took inspiration from some of the historic Venetian floors he saw in Italy. He recreated the look with his trademark color-upon-color process. This layering is possible only with water-based stains, Harris says.

Another factor on the plus side for acrylics is color selection, according to many contractors and dealers, including Doug Bannister, owner of Cimarron in Oklahoma City, which produces a line called SS Rainbow Stain System.

When the concrete industry uses acid staining, color selection is limited by the concrete “canvas” you have to work with, Bannister says. Water-based stains offer a nearly unlimited range of colors, he says, and this wide range helps make concrete a top choice for designers.

If concrete has already been colored by acid stain, a painter may still find a market in enhancing that color. Most water-based stains can be used to enhance or even rescue acid stain jobs that didn’t turn out as planned, Bannister says. Colors can be modified, intensified or diluted by adding more or less pigment to the base. On top of that, acrylic stains generally cost less to buy and to apply in comparison to acid stains.

Preparation is paramount
Sound good? There is more to consider. As a painter, you know the importance of prepping a surface. When it comes to concrete, the surfaces are most often outside, underfoot, or in a commercial setting and intended to hold up for a long, long time. To do it right, you have to start at the start.

“You almost need to be an extremist when it comes to preparation,” Harris says.

That means prepping the surface to an industry-standard profile. If the surface isn’t mechanically and chemically ready to receive the stain, says Chuck Brunner of Smith Paints in Harrisburg, Pa., the coating is likely to fail.

Acrylic stains come in two basic categories. One penetrates the pours and bonds, the other fastens to the surface. Both require porosity to do their work.

The first consideration is to know exactly what profile the product requires. “That’s paramount,” says Harris, who uses a variety of acrylic stains.

Sources for this article says that most products require an International Concrete Repair Institute profile of 1 or 2. The product you use will specify on the label. Getting there is the tricky part.

If a painter was to ask around or search the Internet about how to take a concrete surface down to this relatively shallow profile, muriatic acid is one of the first solutions that will come up. It will sound easy. However, those with the most experience advise those with less experience to steer clear, or at least be aware that it’s harder than it looks.

Brunner from Smith Paints says he does not recommend muriatic acid etching by anyone with less than 10 years experience. The reason, he says, is that it is prone to backfire. There is mess, odor and regulations governing hazardous materials, all of which are compounded in interior settings.

Second, he says he often sees inexperienced contractors fail to neutralize the acid properly. Any leftover acid builds chalk on the surface of the concrete, which forces the topical stain to fail, which costs the contractor a lot of money.

For interior surfaces, Brunner recommends simply using citric acid mixed with water. The white powder is available through food suppliers. Brunner says this nontoxic acid has the power to etch the profile, but can be washed down drains.

Harris recommends a more traditional approach with muriatic acid, but agrees that even experienced contractors have been known to fail. His process is: pressure-wash, rotary-scrub, wet down, sprinkle with acid, rotary-scrub again, pressure-wash again, neutralize with ammonia bath, rinse.

An alternative on interiors is a dustless grinding machine, which is not readily available to most contractors. Shot-blasting is not recommended for this profile.

For exterior work, Brunner has another common-sense approach. He advises contractors start the project by hiring someone to clean the driveway, specifically someone with a 10-gallon-per-minute machine, a zero-degree rotating tip, and the ability to run hot water. This ensures a good cleaning before profiling.

Once the surface is prepped, water-based stains can be applied in a number of ways. When using staining over acid stain, Harris often uses a pump sprayer. However, he says, airless and compressor sprayers, rollers and brushes can be used, depending on the desired effect.

Once the stain is applied, there is another step. Because water-based stains are topical, they leave a membrane that is exposed to traffic and wear. The color coat has to be sealed.

Barbara Sargent of Kemiko in Leonard, Texas, which distributes the Rembrandt line of acrylic-urethane polymer stains, says that these types of stains should be thought of as an equal part of a three-part product, and each third must be of good quality. The first part is the properly profiled surface. The second is the stain. And the third is the sealer.

For a topcoat, acrylic urethane, polyurethane, or epoxies are commonly used. Some stains cannot take a solvent-based sealer, Harris warned, so as usual, be sure to know the manufacturer’s recommendations.

For high traffic areas, Sargent recommends a sacrificial layer. She, like others in the industry, also recommends that contractors sell the installation with an annual maintenance contract, or at least make sure that the customer is well informed on how to maintain the piece.

Harris agrees. He advises colleagues to sell a maintenance contract with the installation, or teach the client how to do an annual deep scrub and rinse and reseal on exterior surfaces, and how to wax interior floors each year.