Canadian Finishing & Coatings Manufacturing Magazine Jan/Feb 2023 - 27

INDUSTRIAL FINISHING: MANUAL SPRAY GUNS
woodworking, it's used for cabinets and large volume products of
the same colour. "
From there you get into pressure pots and gravity fed cup guns.
" The pressure pot guns are typically used on transport trailers,
as one example, while the cup guns are more for automotive and
smaller refinishing tasks, " says Schweighofer. " Every time a new
paint line is released, SATA works with the paint manufacturer to
make sure that the guns spray the product properly. "
Atomisation is always being improved as it controls the
droplet size and how the finish will look on the panel or surface
that is being painted. Of course, over atomising the product can
also be an issue depending on the product and the environment.
" In Alberta, for example, where it's so dry, we use a bigger
tip size especially for waterborne paints. If you over atomise
in a dry climate, by the time the product hits the panel it will
want to become seedy and it can sand pile on the edge if you're
doing a blend, " says Schweighofer. " So from that point of view,
atomisation is determined by the gun and paint manufacturers
based on what they want to see for film thickness, droplet size,
etc. And it determines your speed too. "
SATA supplies a cert chart with its equipment that comes
with a ruler for measuring high volume, low pressure (HVLP)
and reduced pressure (RP) for certain distances between the
gun and the panel. With the ruler, operators can check the gun
and test spray the fan pattern at the recommended pressure.
Gun settings are also determined by paint manufacturers, which
supply technical sheets for pressure settings.
" The settings determine the speed that you move at. If the
spray distance or fan pattern is not wide open, for example, it
can give you striping, or the overlap would be inconsistent and
cause runs. And the orange peel or the texture of the finish will
change, " says Schweighofer. " With gun settings you have a fan
pattern, which is the height of the fan or air pressure and fluid
control. Those three combined can really alter the finish. If your
fluid control is in too far it will split the pattern and you'll have
a stripe at the top and bottom, and the center will be dry. Also, if
the air pressure is too high there can be excessive product coming
out or if you have an improper nozzle size it can cause paint waste
and excessive overspray. And if the pressure is too low, depending
on the paint line, you can get solvent popping or hazing because
you're loading on too much product. "
These are all factors and variables that a painter needs
to consider when dialing in the gun settings. And while
Schweighofer says painters typically get a feel for proper settings
when using different products, using the technical references
supplied by the manufacturers and using the cert chart sheets to
test the spray patterns is always a good reference for painters that
run into issues or start noticing defects.
Perfecting Manual Powder Processes
Manual powder coating guns are still a very important tool in
the coating market as every company relies on some amount of
manual coating to apply powder to parts. And according to Jeff
Hale, marketing manager for Gema, many companies are seeking
equipment that's easy to use, reliable and durable, but also
efficient and capable of delivering a repeatable result.
" Users of manual guns also want equipment that's easy to
clean, while providing excellent colour flexibility, " says Hale.
" But one of the biggest challenges for operators is putting too
much powder on a part. This is due to a variety of reasons, but
January/February 2023
27
Atomisation is always being improved as it
controls the droplet size and how the finish
will look on the panel or surface that is being
painted. Of course, over atomising the product
can also be an issue depending on the product
and the environment.
Canadian Finishing & Coatings Manufacturing Magazine Jan/Feb 2023

Table of Contents for the Digital Edition of Canadian Finishing & Coatings Manufacturing Magazine Jan/Feb 2023
