(1 of 5) Nock-Off from Surface Koatings is a new environmentally friendly stripper for concrete that's safe for both indoor and outdoor use.

(2 of 5) Nock-Off was put to the test on a 3500-psi exterior test slab finished with color hardener and texture skins. The challenge was to remove two layers of polyaspartic polyurea coating that were applied to the slab with a roller. The first coat was a 50%-solids polyaspartic, followed by a generous topcoat of 70%-solids polyaspartic.

(3 of 5) Nock-Off was applied with a 3/8-inch-nap roller to half of the polyaspartic-coated surface at a coverage rate of approximately 100 to 125 square feet per gallon. It was then allowed to sit for 3 hours to break down the coating.

(4 of 5) A 2500-psi pressure washer removes the polyaspartic coating from the areas treated with Nock-Off.

(5 of 5) The results. The light gray slab sections show where the coating was successfully removed.

To remove old coatings and sealers from concrete before applying stain or other decorative treatments, contractors often turn to potent methylene-chloride-based chemical strippers. While these products can be effective when applied properly, they can also be harsh on the environment and hazardous to work with. They "will take the skin off your fingers, given the chance," says Concrete Network technical expert Chris Sullivan. Newer environmentally friendly soy-based strippers are safer to use, but they require more time to work, can be messy to use, and are often ineffective at removing tenacious industrial-strength coatings.

A new environmentally friendly stripper called Nock-Off, from Surface Koatings, Mount Juliet, Tenn., is said to overcome these drawbacks with its safe but powerful stripping capabilities. The product is biodegradable and VOC-compliant in all areas of the U.S., yet is formulated to remove tough acrylics, urethanes, polyureas, polyaspartic polyureas, latex paints and oil-based enamels from concrete and other surfaces, according to Todd Winters, president and technical director of Surface Koatings.

"After 22 years in the industry formulating, manufacturing, and testing various coatings and strippers, I have found that Nock-Off is by far the best overall stripper of acrylic sealers that I have tested," he says. "You get better results with less time and mess. Nock-Off is not sticky, like soy-based strippers, and is not harmful like harsh methylene-chloride-type strippers."

Another advantage of Nock-Off is the savings in labor costs compared with mechanical stripping methods, Winters adds. "If you have to strip a stamped, stenciled, or textured outdoor concrete surface, you would normally have to sandblast to remove the coating, which is very tedious and expensive. With Nock-Off, you simply roll the coating on the substrate and cover with poly sheeting, wait 1 to 3 hours, and wash it off with a high-pressure washer, repeating if necessary."

In addition to being user-friendly, Nock-Off is completely safe for indoor use. That's one of the reasons that contractor Ryan Samford of Epo-Floors, Franklin, Tenn., switched to the product. "Other chemical strippers I've used are too caustic for use indoors. Nock-Off has a pleasant cherry-like scent, with no fumes or offensive odors." Samford recently used the product to strip a polyaspartic coating from some concrete countertops that needed to be restained. First, he tried to mechanically remove the coating by diamond grinding, but had no success. However, applying Nock-Off in two separate applications, followed by scraping, did the trick.

Samford has used Nock-Off successfully on several projects to remove acrylics, urethanes, polyaspartic coatings and oil-based paints. Nock-Off can also be used to remove some cementitious overlays, according to Winters. However, there are certain materials the stripper can't remove, including some epoxies and mastics, so conducting a test prior to application is recommended.

Nock-Off is sold throughout the U.S. by various distributors, and is available in 1-gallon cans, 5-gallon pails and 55-gallon drums. For more information, including a product data sheet and instructions for use, visit www.surfacekoatings.com.

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