Secrets of Better Concrete Stenciling
by Gail Elber
concrete or to rejuvenate existing concrete, stenciling is a decorative application worth considering. It may seem like a simple process, but a few fine points separate nice-looking, profitable stencil jobs from the rest. We've asked some experienced stencilers for tips to elevate your stenciling jobs from so-so to spectacular.
First, when you're planning your pours, consider where your crew will walk and stand during the job. If you're doing an indoor floor with walls all around, you'll need to break it up into two pours, first doing a strip all around the edge so that you'll have someplace to stand when you do the center. For an outside patio that abuts a fence or wall, perhaps the client will agree to strategic placement of a flower bed. Or you may be able to erect a scaffold to stand on.
 As with all decorative work, you and the client must agree on the final effect. Sample boards let you fine-tune which shades of color hardener to use and show the client exactly how deep the grout joints will be and what the texture will be like, avoiding unpleasant surprises. But, "don't make your mock-ups look better than what you'll be able to do out on the job," warns Frank Piccolo of the stencil manufacturer Art Crete. "When you're doing a little 4-by-4 board, you can always do detail work that's difficult to do when you're out there doing hundreds of thousands of square feet of the stuff."
Stenciling newly poured concrete takes a little finesse. Once the slab is poured, finish the concrete with a bull float and edge it. Then lay the stencil on the wet concrete, unrolling it from the top of the roll so that it will lie flat.
Clark Paepke of DC Concrete in Salt Lake City, Utah, a distributor for Stencil Systems, suggests embedding the first roll of stencil into the surface with a stencil roller, a napped roller about 18 inches wide that fits on a bull-float handle. Apply the roller from the center to the edges to press out any bubbles. Then smooth the surface with a fresno. "You get more control out of the fresno because it's lighter than a bull float." Then lay, roll in and fresno the next course of stencil, placing the trailing grout line of the second course on top of the leading grout line of the first. Trim the stencil with scissors.
 Next, broadcast color hardener on the surface. Using more than one color creates a realistic effect. When you're broadcasting powdered material, toss it up so that it rains down onto the concrete. Don't throw it into the surface, which can make the surface uneven. Bull-float the surface after the color is applied according to the color manufacturer's directions.
At this point, you can apply a liquid or powdered release material in a third color, then texture the surface with a heavy texture roller or a texture mat. Wear texture shoes to walk on the concrete when it's at this stage.
When the concrete no longer yields to the pressure of a thumb, remove the stencil, walking on the concrete in stocking feet or texture shoes. The longer you wait, the crisper the edges of the faux masonry. If you want to remove the stencil earlier, when the concrete is still soft, you should have two people lift it, one on each end, making sure that it doesn't drag on the concrete. No matter when you remove the stencil, before walking on the area from which the stencil has been removed, blow off the surface with a leaf blower so that chips don't get ground into the surface. Then rinse the area with water.
As soon as the surface is clean and dry, apply a cure-seal compound. As with any decorative concrete surface, make sure the client understands the need to apply sealer regularly.
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