Most large guns are siphon feeds simply because
it's awkward to balance and support a quart of
paint if it's centered above your wrist. Most of
the touch up professional quality guns are gravity
fed. While there may be some technical merits
to this design the biggest advantage I find is
how
easy they are to clean compared to the siphon feeds.
HVLP Guns
I should mention that a bit of a revolution has
occurred in the last five years regarding spray
gun design. For years the typical siphon feed gun
used high pressure compressed air to atomize the
paint and apply it to the surface. While the end
result of spray painting anything is to apply the
material to a surface, the new guns use a technology
called High Volume Low Pressure or HVLP to get
the job done.
The motivation for this change was
primarily to meet strict standards that the EPA
imposed regarding overspray and paint emissions.
Anyone who has used the old style, high pressure
guns knows what a fog of overspray mist is created
when painting even the smallest objects. The
HVLP guns reduce these emissions dramatically.
They
still use the same pressure into the gun (30
- 50psi) but the pressure at the tip of the gun
is reduced
to 10 - 15psi which stops the huge overspray
fog that the old guns emit. The side benefit to
these
reduced emissions is how efficiently the guns
apply paint to the surface. Where the old style
guns
shot 2/3rds of the paint into the atmosphere
in the form of overspray, the HVLP guns stick
this
paint to the surface you are spraying,
the net result is far less paint used for a given
area painted.
The paint saving is quite dramatic and takes
a while to get used to if you are used to working
with the old style guns. With my own equipment
it took quite some time for me to stop mixing
up
the big batches of paint I did before switching
to an HVLP gun.
Airbrush
The third style of gun we would commonly use
is called an airbrush. These tiny little creations
apply miniscule amounts of paint in a very controlled
fashion. They are commonly used for graphics art
work where precise control is required and you
aren't looking to cover a large area with paint.
These guns, surprisingly, don't get much work for
the types of painting we do. Unless you are laying
down fancy graphics and intricate designs, our
purposes are better served with the touch up gun. |