to Stain Concrete
The work of other trades
also can affect staining results. For instance, dry-wall
dust on a surface to be stained will react with the
stain, coloring the surface differently wherever it’s
present. And spills of grease and oil, other lime-based
materials, paint, or caulk before or after staining
will produce unwanted color variations. A good relationship
with the owner or project manager helps to prevent
such mishaps. Project management should ensure that
the floor isn’t damaged before or after staining
and keep other trades away from areas where surface
preparation and staining are in progress.
If an installer other than the concrete contractor
applies the chemical stain, the contractor and installer
must agree on the following:
Pour schedule. To get a rich color, some installers
begin staining with diluted materials as early as
a day or two after the concrete has been placed. For
uniform results, they need to stain each placement
at exactly the same age.
• Jointing method. For slabs requiring sawed
control joints or pat-tern lines, dust or sawing slurry
must be removed before any of it bonds to the slab.
Otherwise, stain color at the joints will differ from
the color of the rest of the surface.
• Finishing process. Although Jones likes to
work on a hard-troweled surface, some installers prefer
finishes that more readily accept the stain. Uniform
finishing throughout the job helps to ensure more
uniform stain penetration.
• Curing method. Do not use plastic sheeting,
liquid membranes, or wet curing methods because they
can trap moisture and cause efflorescence.
It’s often best to install chemical-stain finishes
and a first coat of sealer, and then protect the floor
surface with a cover before allowing other trades
on the floor. Unfortunately, any protective material
will affect the final appearance of the stained floor
to some degree, usually by leaving an outline of its
shape on the floor and by darkening the surface a
bit. Don’t use any cover material that doesn’t
allow water vapor to escape. Breathable cloth tarps
are perhaps the best covers for preventing discoloration
caused by the work of other trades.
continue – Surface Preparation