The
singular most important component
of any organic finish that affects
its quality (durability) is its resin
base.
That is, the bonding agent
in to which the colorants (pigments)
are added.
The
comparison of "Liquid
vs. Powder" is a misnomer
when applied to a quality comparison
and simply describes the process by
which the coating is applied.
It
is important to recognize that a powder
polyester has the same (chemical)
properties as a liquid polyester,
and that a powder acrylic has the
same properties as a liquid acrylic.
Similarly, a powder flouropolymer
(i.e. Kynar 500) has the same properties
as its liquid counterpart. Therefore,
our standard Acrylic Enamel
finish is equal to or better than
most pre-fab powder coated fencing
products on the market.
A
physical attribute of powder
coatings is that because of the process
by which the raw materials are processed
(grinding from solid) and applied,
they generally tend to be thicker
finishes than liquid, but again, it
is important to remember that it is
the resin base of a coating that most
affects its durability in service
life, not its thickness.
In
addition to the resin selection, another
critical ingredient to ensure long
term durability is the preparation
of the aluminum surface prior to painting,
and while there no specified requirements
for the low to mid range coatings,
the industry's highest specification
for coating aluminum (AAMA 2605) mandates
that the surface of the aluminum be
chemically converted to amorphous
chromium phosphate prior to coating
with flouropolymer finishes. This
is the same pretreatment that is also
exclusively specified for military
aircraft. All of our powder finishes
include a chromium conversion coating
as the critical first stage of the
painting process. This is why there
is a moderate charge for our superior
powder coated finishes, and an additional
3 weeks lead time for products to
which powder coating is requested.
In
summary, when selecting a finish for
an externally exposed aluminum
product,
it is prudent to consider:
(1)
The Resin Type, not the application
process
(2) The Preparation
and Pretreatment of the material
(3) The Warranty
Coverage
Thicker is
not always better
There is simply
no pretreatment equivalent to chrome
and even much thicker powder coatings
simply take a little longer to fail.
