Demonstrations seen on a trade-show floor make stamped-concrete installation look like a snap — just color, stamp and seal. But veterans say otherwise.
After all, you’re transforming simple gray concrete into
brick, flagstone or cobblestone. The coloring and stamping require
care. Then there’s the “hand-tooling”
that’s needed to texture the edges and tight spots where a
stamp won’t fit. Timing becomes even more important because
you must complete the stamping before the concrete
Mastering stamped concrete takes time and attention to detail.
Here, we take you through the process.
STAGE ONE: ADDING COLOR
Installers most commonly color the concrete with one of two
methods: “integral color” or “color
hardeners.” Each has its own benefits and drawbacks.
• Integral color means that the concrete comes from
the batch plant already tinted. The slab will be colored throughout
its entire thickness. Because crews don’t have to worry about
adding color, this option may work best for beginners or small
teams that want to concentrate on learning to texture the concrete.
This product comes in fewer colors, partly because it can’t
be tinted lighter than the concrete’s original gray.
• Color hardeners are applied and then troweled into
the slab’s top couple of inches during concrete placement.
They’re called color hardeners because they increase the
concrete’s surface strength to 7,000 to 8,000 psi of impact
resistance, says Clark Branum, director of technical services at
Brickform Products in Rancho Cucamonga, Calif. Color hardeners
provide a greater selection of hues and can produce lighter shades,
including white. This product adds an extra step, however, so
beginners or smaller crews may want to avoid it — or at least
train with color hardeners on smaller projects.
Follow these guidelines during the coloring phase:
Watch the mix as it comes from the plant. Make sure that
proper consistency and color are maintained from batch to
Avoid adding water. Wetting an integral color mix might
change the shade. If you need to slow down the set, consider using
plasticizers and water reducers, Branum says.
Protect all adjoining areas. The powder that creates the
color is broadcast by hand and will scatter. Upon contact with
moisture, it will become active and color any surface upon which it
lands, making it difficult to clean.
Distribute evenly. Be sure to apply the powder with a
consistent level of thickness to prevent uneven
Manufacturers typically recommend one 60-pound pail per 100
square feet (or 0.6 pounds per square foot) for standard colors.
Lighter colors may require more. To help ensure even application,
divide the deck into 100-square-foot sections. Place a 60-pound
pail in each area, so you know how far each bucket must go,
recommends Bob Harris, president/owner of the Decorative Concrete
Institute in Douglasville, Ga.
Saturation. Color hardener is a powder, so it can become
cakey if there’s not enough surface moisture to saturate it.
This can cause dry spots, which makes the powder difficult to work
in and, in some cases, could cause delamination down the
One clue to finding the proper amount of water lies in air
entrainment. Too much air means not enough water, Branum says.
Ideal air entrainment depends on regional conditions, but it
usually falls between 3 percent to 5 percent. Anything above 6
percent is probably too high.
Apply the powder in two stages, beginning with the first 60
percent. Wait for it to absorb the moisture from the concrete. This
can take five to 10 minutes, depending on heat and humidity.
(Don’t wait too long or the powder will begin to dry and form
a crust.) Then float the powder in. Finally, go through the same
process with the remaining 40 percent of the color hardener.
STAGE TWO: RELEASES
Once the concrete has been poured, colored and troweled, it must be
prepared for stamping. This requires a release agent — a
substance that prevents the texturing tools from sticking to the
mix. Release agents come in liquid form or a powder called color
Color releases not only help separate the concrete and tools,
but they can also add extra tint, resulting in an antiquing effect.
The added layer of color becomes embedded into the joints,
fissures, veins and crevices left by the stamps to enhance the
Powder releases are scattered over the top of the freshly
troweled slab. It’s a little messier than the liquid form
because residual must be washed off two to three days after
Liquid releases are cleaner; however, they are not tinted. Some
installers will compensate for this by adding a little powder color
release to the liquid release.
When working with release agents, keep these tips in
Apply the right amount of color release. Without enough, the
texturing tool may stick to the concrete and leave a grainy look.
Too thick a layer will prevent the concrete from receiving the
stamp’s full impression, resulting in a shallow texture,
and/or spots with no texture at all. “They can end up
texturing the release and not the concrete,” Branum
As a general rule, disburse evenly at a rate of 3 to 4 pounds
per 100 square feet of concrete, Harris says. At that rate, a
5-gallon pail will cover approximately 1,000 square feet.
Precondition the stamping pad. To ensure that the stamp will
lift easily off the concrete, brush a layer of the powder or liquid
release onto the bottom of the mats.
Combine releases for extra color depth. Combining colors can
make the surface look more authentic. This is done by using an
integral color with a couple of color hardeners and two or three
color releases. If a client wants the look of a specific stone,
carefully examine a sample of it for color, then choose your
various tints appropriately. It’s best to stay within the
same family of hues, advises Rick Wild, owner of Creative Concrete,
LLC, an installation company in Perrineville, N.J.
STAGE THREE: THE IMPRESSION
Once the slab is prepared, it’s time to begin texturing the
concrete. The rigid rubber stamps generally come in two varieties:
a patterned type made to look like brick or stone, or continuous
texture, which features background veins, fissures and other
irregularities. The stamps are placed on the concrete, and
installers walk on them or pound them with tamping tools to make
sure they go in deep enough. Then each stamp is lifted and
repositioned next to the last one that was put down. It’s
like an intricately choreographed game of
When texturing the concrete, consider these suggestions from
Don’t skimp. Have enough stamping tools on hand to
span the complete width of the area to be stamped, plus two.
Without enough stamps, you can’t move fast enough and the
concrete will dry. In addition, the stamps are used to secure each
other while installers walk or pound on them. Otherwise, the tool
Watch the timing. Before stamping, make sure there is no
standing water. Then ascertain that the concrete is plastic enough
to support the installer. “If [the concrete] is too soft,
installers will fall right through and make holes in it,”
Branum says. On the other hand, if it’s set too much, you
won’t be able to make enough of an
Check the set with your thumb: It should leave a mark, yet
there also should be resistance from the concrete below, Branum
The timing will vary slightly from stamp to stamp. When
creating a shallower texture, such as some wooden plank varieties,
allow the concrete to set a little longer. When using deeper
patterns, such as flagstone, the concrete should be a little
Set the stamping tools square to each other and
“randomly.” The stamps should interlock, with no
gaps in between. And don’t put the same tools next to each
other. You want the surface to be randomly patterned, like a true
stone or brick deck. Manufacturers have made this easy, either
numbering or labeling the stamps so you know which are alike.
Be careful on a drastic slope. The stamps will want to slide
down, breaking the interlock, Harris says. Start placing tools from
the lowest elevation, working up the slope. That way, each will
have another below it for security.
Lift the stamp quickly and precisely. Generally, the stamps
should be lifted within five minutes, Branum says. If they sit too
long, water from the concrete can begin to form
Remember: When lifting the stamp, the concrete is still
impressionable, so pull the tools up carefully. Use both handles,
and lift them at the same time. “Sometimes guys will grab one
handle and lift the tool, and the bottom edge of the tool will kick
out and tear the surface,” Branum says.
Hand-tool the edges. The stamps won’t end neatly where
you want — at the edge of the slab or where it meets a
vertical structure such as the home or a pillar. You can’t
just jam the stamp to fit in the tight spaces created by the deck
forms or the wall. This is when you must do things by hand. First,
go over the unstamped area with a texturing skin. This flexible mat
is stamped with the background texture that you’re using.
This ensures that the whole area is impressed with the texture.
Next, take a flexible stamp mat with the same pattern as the rigid
tools. Bend it to fit the space and stamp as much of the area as
you can. The mat can’t completely fold, though, so it’s
not going to reach the last inch or two at the very edge.
That’s where you must manually finish the
“joints.” Harris likes to use random-sized hand
chisels, and line them up with the joints left from the stamp to
continue the lines from the pattern.