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For the actual overlay, Percy used Butterfield's Cantera Vertical Wall Mix - about 25 bags total, Percy says. He used an electric paddle mixer to mix the Cantera with water before troweling a thin layer over the whole wall.

To create a unique look, Percy used five different Butterfield Uni-Mix Integral Dry Colorants, mixing each in its own bucket. The color was added to water and then mixed with the Cantera using the paddle mixer. Percy says for this type of overlay you want a "thicker than pudding" consistency with your mix. The colors used included Santa Fe Buff, Sandstone, Autumn Oak, Salt Marsh Gray and Pewter. Some stones were left just the gray of the Cantera mix.

Percy and his crew hand applied the colored Cantera to the wall. "I'd completely walk around the unit with one color and place it randomly all the way around," Percy says. Once all five colors were placed, he went back and filled in the rest of the stones being careful not to have too much of one color in an area. Percy also embedded black glass in some of the concrete stones to give them a quartz look.

Following behind Percy were two crew members with Butterfield stamping skins. They pressed the skins to the recently applied colored Cantera to create the stone shape and texture. A third crew member followed, carving the details to make the stones look like they were embedded into the scratch coat. To do this hand carving Percy suggests using a wooden dowel and a chipping brush to chip off any extra concrete.

After drying for a day, Percy mixed Butterfield's Elements water-based, transparent stain in Stygian (sort of a chocolate brown) with the sealer and sprayed it on the concrete. This applied a protective sealer and gave the stones an aged look, he says. The total project took Percy and his crew about nine days to complete, and the result was a custom vertical stamped overlay that is almost impossible to duplicate.