This issue of the PQI
Contractor Newsletter is the eighth of a
series illustrating the performance benefits of top quality
interior and exterior paints. The information can be
helpful for reducing chance of complaints or call-backs,
and illustrating to customers the importance of using
quality paints.
Illustrating
Performance Benefits of Quality Paints:
Resist Sticking
 Background: Paints,
especially latex types, may tend to stick to each other
when applied to areas that press against each other,
such as a door and the door jamb. This sticking is
referred to as “blocking.” Also, items
such as dishes and books placed on a painted surface
may tend to stick, depending on conditions such as
the temperature, how much pressure is applied, the
nature of the paint used, and how thoroughly the paint
has dried prior to being put into service.
Factors to be Taken Into
Account:
- Latex paint
binders are “thermoplastic”, which
means they have a degree of softness, and they
get softer if the temperature increases. This
can result in sticking if the paints are pressed
together. Thus, blocking can be more of a problem
in hot weather than when it is cooler.
- With
thermoplastic materials, pressure also makes
it softer, so latex paints can be more vulnerable
to blocking if weight or pressure is applied.
- Glossier paints
are generally more subject to blocking than
are flat and satin finishes, so
the latter are often a better choice for shelving.
- Tinting colorants
contain surfactants (soaps) and VOCs that can
retard drying and can keep
the paint surface relatively soft, so dark,
heavily tinted paints should be avoided where
blocking might be a
problem.
- Top quality paints are generally made
with binders and additives that are better
at resisting sticking than are economy paints,
so be sure utilize top quality products.
- Drying time is critical in developing
maximum block resistance. VOCs in latex paint
tend
to increase sticking, so because they are slow
in evaporating, advise customers that resistance
to sticking can take
a week or more to
develop.
 Gaskets used in window sashes, storm doors,
etc. often contain plasticizers that can soften
latex paint and cause sticking. Avoid painting
the gasket, and if possible, don’t
paint the area where the gasket will make contact.
- For situations where
blocking is occurring, a quick remedy can be rubbing
some waxed paper on both surface.
- Another approach is applying talcum
powder to the surfaces.
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Click
on the image above to open the printable PQI
sheet illustrating the quality
paint benefit of Better Resistance to Stickng
compared with economy paint.
To see sheets on other quality paint performance
benefits, please visit the Quality
Paint Page on the PQI web site.
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PQI News:
The
Rohm and Haas Paint Quality Institute North America
team attended the National
Association of Home Builders (NAHB) International Home
Builders’ Show (IBS) in Orlando, FL. There, hundreds
of suppliers to residential builders exhibited their
products and services. More than ever, synthetic materials
are in the forefront, for the most part replacing wood
for a broad range of uses including:
• Siding • Decking • Exterior
Trim • Interior Trim • Flooring
• Outdoor Steps & Railings • Outdoor Furniture • Entry
Doors
• Windows
 Painting contractors doing new residential construction can encourage the builder
to paint any of these surfaces. PVC trim is often painted for uniformity
of appearance because it is face-nailed in place. But otherwise, builders and
new home buyers
often don’t know that they can have the color* and sheen or gloss level
they’d like, by having the material custom painted. Of course, the same
goes for buyers and owners of existing newer homes. Contractors
can use the PQI booklet, Painting Today’s New Substrates,
as a selling tool with builders and homeowners. This can be ordered through
THE PQI STORE, and can be viewed by CLICKING
HERE. Also, the PQI InfoSheet
on painting PVC trim can be helpful… CLICK
HERE.
*For vinyl siding and other thin vinyl (PVC) materials, a
dark color should not be used (unless recommended by the siding or paint manufacturer)
because of possible warpage of the surface
resulting from heat absorption.
Q & A:
Q: I
see
paint brushes made with
Nylon and with polyester, for latex paints. What’s the difference?
 A: 100% Nylon filaments provide the smoothest finish among the synthetics. Their
shortcoming is that they tend to get limp with extended use, particularly in
warm weather, which makes them less popular among contractors for exterior use.
Polyester is on the other side of the coin, maintaining shape better but not
applying as fine a finish. Polyester/Nylon blends are of course in the middle.
Some suppliers are providing polyester brushes in different degrees of stiffness,
which depends in part on the filament diameter. In PQI, we encourage painters
to apply latex paints in a heavy coat, with just a couple of strokes - a thicker
coat flows out better.
The Rohm and Haas Paint Quality Institute
P.O. Box 1348
Philadelphia, PA 19109
215.592.3000
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