Concrete scientists can create a mix design that provides a century of service, but some surface treatments have yet to show similar longevity. So it’s not surprising that customers often ask how to revive the beauty of decorative projects treated decades earlier.
Since over time UV exposure, foot traffic, and cleaning will fade older surface protectors, what’s usually happened is that the acrylic sealer is showing its age. Because the slab is structurally sound, your job is to remove and replace the acrylic coating.
There are several ways to do this. However, most involve mechanical abrasion that damages textured surfaces, especially stamped concrete.
Another is to apply a poultice. For example, when faced with an oil spill, you place absorbent cloth over the stain and pour water on it. The water draws the oil up into the cloth by a process called wicking.
Nox-Crete Products Group introduced a two-component poultice that combines chemical and physical processes to remove sealers without abrasion. Designed for exterior applications like driveways, patios, and sidewalks, Deco-Peel and Deco-Peel CPC (consumer products-compliant) consists of an engineered fabric blanket and a specially formulated cleaning solution.
Simple, two-step process
Lightly sweep the surface to remove dirt and debris. Should the surface require cleaning with water, the manufacturer recommends the slab dry for at least two days.
Unroll the fabric blanket and spread it on the slab’s surface, taking care to minimize edge overlap because the process relies on the wicking up of the removal solution. It’s very important that the blanket remain in contact with the surface; some contractors place weighted objects on the fabric to eliminate wind uplift.
Once the blanket is spread and secured, use thick nap rollers to over-wet the fabric with the removal solution. The goal is to not only impregnate the fabric, but to allow gravity to force the product down onto the slab’s surface. Coverage rates vary based on the coating’s thickness, hardness, and concrete surface density.
There should be a slight initial ponding as the chemical contacts the sealer. Don’t apply any water to the fabric once you’ve rolled on the cleaning solution. The blanket becomes translucent, and you’ll see the slab’s surface texture through the fabric.
The product reacts with old sealer to wick the now-liquified old sealer up into the fabric. You can expedite the process by placing fans near the slab’s surface, but nature’s gentle breeze does quite well. The best results are obtained when the impregnated fabric is left overnight on the slab. You’ll know when the transfer is complete because the fabric dries and stiffens.
The next day, peel up the fabric and throw it away.
The surface is now free of the old sealer and any corrosive residue.
Most jobs require only one application. But if the old sealer was too thick, or the surface is uneven, immediately repeat the process.
Workers wear standard personal protective equipment. The cleaning chemical has a strong odor that dissipates quickly, so the worksite should be open and well-ventilated. Keep any ignition sources away from the worksite.
Let the slab set for at least 48 hours to enable any remaining cleaning solution to dissipate. On most surfaces, no additional prep work is needed before applying a new coating or sealer.
Although Deco-Peel was designed for flatwork, Nox-Crete is developing a version that can be used on near-vertical surfaces.
See Deco-Peel in action at 2016 World of Concrete’s Slab Construction Showcase Feb. 2-4.