Quality
Exterior Primers Provide Many Benefits
In
order to get the best exterior painting results, it's often
necessary to use a primer or sealer before applying the paint.
But deciding when to use a primer or sealer can be confusing.
The Paint Quality Institute, a leading authority on paints and
primers, explains why primers are so important, and on what
types of jobs they should be used. All
top quality exterior primers help paint adhere better to the
surface that's being painted. They do this by making the surface
more uniform for the top coat, so that when the paint is applied,
it can get a better "grip" than it would on the bare surface.
Primers
also help give the finished paint job a more uniform appearance
in terms of color, hiding and sheen. This is especially true
when the surface being painted is porous or is uneven in porosity.
If
there are stains on the surface being painted, some primers
can help prevent them from "bleeding" through the paint and
ruining its appearance. Not all primers have stain-blocking
capability. If you are interested in this feature, check the
label to make sure the primer you purchase is the stain-blocking
type.
Experts
say that almost any exterior painting project will benefit
from use of a top quality primer, but there are certain applications
where a primer is essential: namely, when painting new wood,
bare stucco, or any surface that has not been previously painted.
You should also use a primer when repainting an uneven or
deteriorated surface or a surface that has been stripped or
is worn down to the original material.
Certain
applications call for a specific type of primer. The Paint
Quality Institute offers these guidelines:
Wood:
On new, unpainted wood, use a quality acrylic latex or oil-based
exterior primer. While quality latex primers will block stains
from wood such as cedar or redwood, use an oil-based stain-blocking
primer if the boards are particularly dark or highly prone
to staining. Always prime and paint bare wood within two weeks
of its first outdoor exposure to keep fibers from deteriorating
and reducing adhesion.
When
painting weathered wood, first scrape and sand the wood thoroughly,
then apply a quality exterior latex or oil-based primer. When
working with previously painted wood, scrape off all loose
paint and feather-sand rough edges and bare spots before applying
the primer.
Stucco
and Masonry: On new masonry, or older surfaces
that are very porous, use a latex masonry sealer or primer.
If you are repainting masonry, at a minimum, spot prime where
the old paint has been removed.
Aluminum
or Galvanized Iron: First remove any white powdery
oxide, using a non-metallic scouring pad or steel wool. Rinse
thoroughly. If steel wool is used, every residual particle
of it must be removed. Then apply a corrosion-inhibitive metal
primer.
Ferrous
Metals: If there is
any rust, remove it with a wire brush, then rinse and allow
the surface to dry before applying a latex or oil-based rust-inhibitive
primer. Two coats of primer will provide added protection
against future rusting.
For
more information on primers or other painting topics, visit
the Paint Quality Institute Web site at www.paintquality.com.
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