Figure 14-40.—Spray kit self-pressurized.
Air regulators are equipped with a pressure valve
and pressure regulating screw to regulate the
pressure delivered to the spray gun. They also
prevent pressure fluctuations. The air must pass
through a sack or cleaner before it leaves the
regulator. This cleaner is contained in the long
cylindrical part of the regulator and should be
drained daily. Air regulators are also equipped with
two gauges. One shows the pressure on the main line
while the other shows the pressure to the spray gun.
SPRAY GUN TECHNIQUE
Proper spray gun technique reflects knowledge of
the equipment and experience. The spray gun should
be held so the spray is perpendicular to the area to
which the finish is being applied. You should ensure
that the prescribed gun-to-work distance is
maintained.
A distance of 6 to 10 inches from the gun to the
work should be maintained when you are spraying
epoxy-polyamide and polyurethane finishes. The gun
should be held 8 to 10 inches from the work for
lacquer and 6 to 8 inches for enamels. For a narrow
pattern, the gun is held at the farther distances (10
inches for epoxy-polyamide and polyurethane, 10
inches for lacquer, and 8 inches for enamels).
A distance of less than 6 inches is undesirable
because the paint will not atomize properly, and an
orange peel will result. A distance of more than 10
inches is equally undesirable. Dried particles of paint
will strike the surface and cause dusting of the finish.
Examples of correct and incorrect spray gun
techniques are shown in figure 14-41.
The distance the spray gun is held from the work
is important; however, there are other factors to
consider. The manner in which the gun is held and
operated is also important. See figure 14-41. You
should move your arm and body with the gun to keep
the spray perpendicular to the surface. Avoid pivoting
and circular movements of the wrist or forearm.
These may bring the gun closer to the surface.
Figure 14-41.—Correct and incorrect methods of
spraying.
14-43
