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Evaluating the performance of UV-durable coil coatings
by Scott W. Moffatt
Photo © Steve Wanke Photography
ALTHOUGH SILICONE-MODIFIED POLYESTER
(SMP) AND SUPER-POLYESTER COATINGS ARE
WELL-SUITED FOR SPECIFIC APPLICATIONS,
THEY CANNOT PROVIDE THE SAME PROVEN LONG-
TERM PERFORMANCE AS 70 PERCENT POLYVINYLIDENE
FLUORIDE (PVDF) PRODUCTS.
While many SMP and super-polyester coatings are excellent
products well-suited to various architectural and building
product applications, the practice of marketing them as
comparable alternatives to 70 percent PVDF coatings may
cause architects and speciﬁers to select the wrong product
for their applications.
This article examines differences between 70 percent
PVDF, SMP, and super-polyester coatings, and explains why
the ﬁrst type generally retain its color and gloss longer than
coatings based on the other chemistry.
Coil coatings are made from three basic ingredients: resins,
pigments, and solvents.
Resins Resins give coil coatings basic performance attributes such
as resistance to abrasion, scratching, moisture, and ultraviolet
(UV) light, as well as mechanical characteristics like adhesion,
hardness, and ﬂexibility during fabrication.
Coil coatings are formulated with several resin types, including
acrylic, epoxy, polyester, and PVDF polymers. For applications
demanding a highly durable coating surface (e.g. metal rooﬁng,
composite panels, building panels, and curtain walls), 70 percent
PVDF coatings are regarded as superior because of their
strong UV resistance. Due to their lower cost and harder
ﬁnishes, SMP and super-polyester coatings are traditionally
favored for applications such as warehouses, industrial,
storage, and agricultural structures, and other non-monumental
In recent years, some manufacturers have sought to position
SMP and super-polyester coatings as viable, low-cost alternatives
to 70 percent PVDF coatings. While it is true polyester coatings
are more resistant to UV damage than early-generation coatings,
they do not offer the same weatherability, color retention, and
gloss retention as 70 percent PVDF coatings.
36 the construction speciﬁer | march 2013
2/14/13 10:03:06 AM