© American Chemistry Council
ANALYSIS
SPECIAL ON PLASTICS, MDF & GLASS
Painting Plastics Problems Clifford K. Schoff Schoff Associates – Allison Park (PA) – United States
T
hose of you who paint plastics or
and paintability. Due to having lower
of dirt. In addition, plasticizers or other
formulate paints for them know
surface energies and polarities, many
components may come to the surface over
that plastics are very different
plastics tend to experience more wetting
time. These surface contaminants must
from metals and can be considerably
and adhesion problems than do
be removed. However, not every bump or
more difficult to paint. Paints over plastics
pre-treated metals.
irregularity in a coated surface is due to
suffer many of the same problems as
Substrates must be clean to ensure good
dirt. Occasionally, what looks like dirt really
those applied to metals, but have a
coating adhesion and minimize defects.
stems from surface damage caused by
number of their own defects. One of the
This is particularly true for plastics, which
moulding problems or bad part handling
difficulties with painting plastics is that
may have mould release agents on their
practices.
there are so many different plastics in
surfaces and seem to have great affinities
Plastics are commonly cleaned by a power
use, each with its own surface properties
for oils, sanding dust, and other kinds
wash followed by a solvent wipe.
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N. 58 - JULY/AUGUST 2019 - international PAINT&COATING magazine