PC Summitry: Options for Low Temperature Cure Powder Coatings
Posted on Monday, October 1, 2012
By Kevin Biller
Why low temperature cure?
The two main drivers for
low temperature cure are:
energy savings and the ability to
coat heat-sensitive substrates.
Reducing energy consumption is a
rather clear and measurable objective.
Tackling heat sensitive substrates
is a more complex proposition.
Standard cure powder coatings
typically require a bake of 15 to 20
minutes at a temperature ranging
from 350°F to 400°F. Depending on
your oven type, production volumes
and energy costs, significant savings
can be realized by reducing the oven
temperature by 25°F or more.
Low Cure vs. Ultra-Low Cure
It is important to differentiate
between coatings technologies that
are suitable for energy reduction purposes
vs. a more complicated
approach that allow heat-sensitive
substrates to be powder coated.
Typically a low cure powder will provide
a reduction in oven operating
temperature with a minimal change
to your application process. Ultra Low
Cure technology usually involves spe-
44 Powder Coated Tough
cialized transport, handling, storage,
application and curing equipment.
Low cure powder coatings are
available from most powder coating
suppliers and will carry a modest premium.
The value of making the transition
from a standard curing product
to a low cure alternative will have to
be carefully calculated. I have provided
an example on how to determine
potential savings of running the same
ware through an oven on a conventional
conveyorized line. It is important
to input the proper data to develop
a meaningful estimate of savings.
The worksheet below requires input
of a number of data relating to your
product and oven engineering. It also
takes into account the type(s) of
metal you are coating, the density of
your conveyor and trolleys and the
insulation of your oven walls.
As you can see, reducing your curing
temperature can provide measurable
savings in operating costs. It is
important to compare these potential
savings to any added costs associated
with procuring a low temperature
What type of performance can you
expect of the lower temperature cure
product? It is always wise to thoroughly
review the technical data
sheet associated with every product
that you buy, however you shouldn’t
expect a reduction in film performance
by switching to a lower curing
product. Exterior durability, chemical
resistance and mechanical performance
should be comparable to the
analogous higher curing product.
Appearance properties may be a little
different. Gloss and smoothness
are appearance properties that can
be affected by a lower curing
temperature. It is strongly
recommended to run the
new product through your
oven with typical parts and
oven loading before committing
to a wholesale change
in your product. You may
have to tweak your oven setting and
line speed a little to accommodate
the new product.
Ultra-Low Cure Technology
Coating heat sensitive substrates
such as engineered boards (e.g.,
medium density fiberboard—MDF),
plastics and light alloys may require
the use of ultra-low cure powder
coatings. These are products that can
cure at temperatures from 200°F to
275°F. Your options for these applications
are either highly catalyzed
thermosetting chemistries or UV curable
With thermosetting types the
same or very similar chemistry is
used as higher baking types; however,
the curing mechanism has been
greatly accelerated with the addition
of a specialized catalyst. This
formulation modification allows the
powder to cure at sub-300°F temperatures.
Ultra-low cure thermosets
typically require a bake time of 20
to 30 minutes. This rather long
duration can be mitigated with the
use of infrared curing technology
which can deliver relatively intense
energy for a short period of time
without degrading the substrate.
UV curing powder technology relies
on first melting the coating then
exposing it to high doses of intense
ultraviolet energy to affect cure. The
advantage of this approach is twofold;
the curing process can be significantly
shortened to around 1 to 5 minutes
at quite low temperatures and
the cure chemistry is stable at ambient
and elevated temperatures. It is
very important to note the criticality
of having all coated surfaces exposed
to the required dosage of UV energy.
If any coated areas do not receive the
necessary dosage, the coating will
undoubtedly suffer catastrophic failure
due to absence of cure.
If you are contemplating applying
powder coating to non-conductive substrates
then you will have to identify
a novel technique to apply the powder.
This can be achieved by preheating
the substrate as commonly implemented
with MDF. If the substrate is
plastic you have a couple options. The
substrate material can be made conductive
by the polymer supplier by
imbedding the plastic with a conductive
agent. This can be expensive.
Otherwise a conductive agent can be
applied to the plastic to make the surface
conductive and the powder can
then be applied electrostatically.
Another very important caveat if
you are considering venturing into
ultra-low cure powder technology –
regardless of cure type (thermoset or
UV cure), you will have to be very
careful with the transport, handling,
storing and application of these products.
To achieve ultra-low temperature
film formation, the powder coating
will possess a low melt point
which can cause the powder to
agglomerate at ambient conditions.
Most ultra-low temp powders will
remain stable up to 75 to 80°F.
Exposure to higher temperatures can
cause serious agglomeration.
Hence you may have to
use refrigerated transportation
for delivery of the product
and you will definitely
require air conditioned storage
and application environments.
process will have to be carefully managed
as well. Ultra-low temp powders
may require careful fluidization conditions
and high velocity powder transport
air must be avoided lest you
invite impact fusion in the transport
hoses and interior gun parts.
In conclusion, low temperature cure
powder coating technology can reduce
your overall operating costs by providing
lower oven temperatures while
providing film performance equal to a
higher baking product. Furthermore,
ultra-low cure powder coatings can
provide new avenues allowing powder
coatings to penetrate unattainable
markets that utilize heat sensitive
substrates. Your best path forward is
to thoroughly research the possibilities
and conduct careful evaluations before
making the transition.
Kevin Biller is a contributing editor of
Powder Coated Tough magazine. He can
be reached via email at