Too little air pressure, coupled with excessive
fluid pressure, causes orange peel.
Excessive fluid pressure causes orange peel and
sags.
Too little fluid pressure causes dusting.
Q5-38.
Regarding painting specifications for letters
and numerals, how is the space measurement
between letters an numerals determined?
Q5-39.
What are tactical paint scheme patterns
based on?
Q5-40.
What type of paint spray gun is designed for
small jobs?
Q5-41.
What is the probable cause if your paint spray
gun is leaking in the front?
Figure 5-42.--Sectional view of typical spray gun.
Q5-42.
What is the desirable distance from the
As the width of the spray is increased, more
surface that you should hold the spray gun in
material must be allowed to pass through the gun to get
order to get the proper coverage and a smooth
the same coverage on the increased area. To apply more
coat of paint?
material to the area, you should turn the fluid needle
Q5-43.
What may cause dusting and rippling in a
adjustment to the left. If too much material is applied to
paint finish?
the surface, turn the fluid needle adjustment to the right.
In normal operation, the wings on the air cap are
adjusted to the horizontal position, as shown in figure
SEALANTS AND SEALING PRACTICES
5-43. This provides a vertical fan-shaped pattern.
LEARNING OBJECTIVE: Recognize the
types of sealants and the procedures used to
Spraying Pressures
apply them.
Normally, you will be concerned about spray
Sealants are used to prevent the movement of liquid
painting lacquer, enamel, and epoxy materials. The
or gas from one point to another. They are used in an
correct air and fluid pressures used with these materials
aircraft to maintain pressurization in cabin areas, to
vary. There are several pitfalls of incorrect pressures,
retain fuel in storage areas, to achieve exterior surface
some of which are as follows:
aerodynamic smoothness, and to weather- proof the
airframe. Sealants are used in general repair work to
Excessive air pressure may cause dusting and
maintain and restore seam integrity in critical areas
rippling of the finish.
where structural damage or paint remover has loosened
existing sealants.
TYPES OF SEALANTS
The physical conditions surrounding the seal
govern the type of sealant to be used. Some sealants are
exposed to extremely high or low temperatures. Other
sealants contact fuels and lubricants. Therefore, it is
necessary to use a sealant that has been compounded
for the particular condition. Sealants are supplied in
different consistencies and cure rates. Basic sealants
are classified in three general categories--pliable,
drying, and curing.
Figure 5-43.--Spray gun nozzle.
5-37
