It has been said, "Every
step successfully completed leads to the successful
completion of the next step." This is certainly
the case with chemical-stain work; proper surface
preparation is a vital step.
Variablilty, not uniformity, is the current trend.
The natural look appeals to many architects and owners.
First, throw a little water on the surface in several
locations to see if the concrete absorbs water. If
it doesn’t, curing agents or sealers may be
blocking the entry of stains and must be removed.
Also remove any grease and oil, paint drops, taping
compounds, caulk, or other surface contaminants.
solvents or stripping agents, sanding, and grinding
are the principal removal methods. To pick up contaminants
more easily, use stripping agents that will mix with
water. If you choose to grind the surface, avoid making
grinding marks that will reflect through the colored
finish by using either a cup grinding head with a
fine-grit (diamond or black abrasive) or diamond pad.
Use a light touch, laying the cup flat on the concrete
and moving it in small-diameter circles until the
If a slab must
be patched, use acrylic-modified, low-shrinkage materials
that will accept stain. These patches will always
show in the finished product, and the owner should
be made aware of this.
To open up the surface for stain penetration, many
installers prefer to sand floors using floor buffing
machines with #60, #80, or #100 paper or screen-mesh
sandpaper that allows dust to pass the pad. This process
can add its own pleasing effect to the final appearance
by accentuating high and low areas on the surface.
(More material is removed from high spots, giving
them a richer color.)
preparation step involves carefully washing the surface
with water and detergent. Don’t use acid to
clean the surface because it will diminish the effect
of the stain. It’s best to scrub with a buffing
machine using strip pads (preferably black) and to
pick up the effluent with a good-quality wet vacuum.
The surface must be clean and free of streak marks,
footprints, and all residues. Anything remaining on
the surface will affect stain penetration.
continue – Sawing and Patterning