From Slump to Stamp: creating better impressions
How to get the best results from stamping concrete
by Denise Wendt
an inexpensive alternative to slate, brick and stone materials while creating the same visual effect. But there are a few tips every installer should remember. Concrete Decor asked veteran concrete professionals to share their techniques for success.
“Concrete is the hardest work on this planet, bar none, if it gets away from you,” says Richard Smith, who owns Richard Smith Custom Concrete in West Hills, Calif. “But with proper planning and a lot of common sense, that doesn’t have to happen.”
“When you finish or stamp concrete it is kind of like Goldilocks’ porridge,” says Tom Ralston, owner of Tom Ralston Concrete in Santa Cruz, Calif. “You can’t have it be too soft or too hard. It has to be at just the right consistency.” Too wet and the concrete pulls the stamps, leaving suction marks. Too dry and it will not leave any substantial embossment or impression.
Concrete tool distributor and trainer Bart Sacco owns and operates Concrete Texturing Tool & Supply in Throop, Penn. “You want concrete that’s workable but not excessively wet,” says Sacco. He uses a 4- to 4.5-inch slump. “As the season progresses I’ll pour tighter to compensate for evaporation,” he says.
 Michael Riggs owns Progressive Concrete Works Inc., in Phoenix. “We place all concrete at a maximum slump of 5 inches,” says Riggs. “Consistency is very important and every load should be placed at the same slump so that the texture and color will be consistent.” A lower slump can also prevent oozing between stamps, says Riggs.
To ensure a consistent impression, Riggs places 4 inches of aggregate base course and then compacts the subgrade before placing any concrete. “We have found that this helps us achieve a more consistent finish and also helps to prevent efflorescence,” he says.
As with all concrete, weather and sunlight affect surface hardness. Surface hardness has a significant impact on the texture as well as the color. When setting up a job with areas in direct sunlight and areas in shade, Riggs says to consider how the inconstancy will affect the finishing. If possible, consider placing the areas separately.
Ralston recommends using a texture roller or a lambswool paint roller to smooth out suction marks that can result from stamping wet concrete. Wedged jointing rollers can be used to knock down suction marks, smooth ridges and clean up the joints between the stamp patterns.
“Many times the oozing is a characteristic a bad set of tools,” says Riggs. If you have a set of tools that you have had oozing problems with in the past, replace the tools, he says.
“Timing is essential in patterned concrete work,” says Sacco. He urges contractors to know the properties of the concrete they’re working with, to know the weather conditions they’ll be working in and to adjust their timing appropriately. “Depending on the time of the year, you’ll either have to speed up or slow down to achieve a nicer stamped impression,” says Sacco.
“When planning and scheduling a project, don’t place more concrete than you can handle,” says Riggs. “Remember the owner is paying you a premium for the stamped concrete and is going to be critical of every small detail.”
Charles Leland, owner of SureCrete Design Products in Dade City, FL, agrees. “Don’t get greedy,” says Leland. “Start with smaller, controllable amounts to stamp in a work day. And don’t be afraid to hire a consultant for a job to ensure success.”
Know your stamps before you get to the job site, says Ralston. He recommends putting down about an inch of sand in a 15x15-square foot area. Wet that down and lay out your stamps. “Do a dry run so you know how these stamps are going to interlock,” he says.
Be aware that the tools will also draw moisture if left on the slab too long, affecting the texture as well as the color, says Riggs. |
Timing is everything
