possible damage may occur to the packing around the
COMMON SPRAY PAINT DEFECTS.--The
valves. To clean a container-type gun, refer to figure
most common defects in sprayed paint are orange peel,
1-22 and follow these procedures:
runs and sags, pinholes, blushing, peeling, and
1. Remove the container from the gun.
· Orange peel is the general term used to describe
2. Hold a cloth over the air cap and pull the trigger.
a dry painted surface that has a pebbled texture
3. Empty the container.
resembling an orange peel. It can be caused by
the improper use of thinners, a spray that is not
4. Pour in a small amount of solvent.
fine enough, too much or too little distance
5. Attach the container to the gun and spray the
between the gun and the surface, improper
solvent through the gun to clean out the
mixing of materials, drafts, or low humidity.
· Runs and sags are usually the result of paint that
6. Soak the air cap in cleaning solvent.
is too thin. They can also result when too much
material is sprayed on the surface, the spraying
7. Replace the air cap.
stroke overlap is too great, improper adjustments
of the spray gun and pressure are being used, or
dirty or partially clogged air or fluid passages
cause uneven distribution.
· Pinholes can be caused by water or excessive
t h i n n e r i n t h e p a i n t . E x c e s s ive l y h e av y
applications of quick-drying paint also cause
pinholes. In either case, small bubbles form and
break when the paint is drying, leaving small
· Blushing resembles powdering of the paint. The
cellulose material in the paint separates from the
solvent and returns to its original powder form.
Water is usually the cause of blushing, either
moisture on the surface to be sprayed or
Figure 1-22.--Steps in cleaning a container-type gun.
excessive moisture in the air. To correct a
Some spray gun troubles, possible causes, and
blushing defect, remove the defective coat,
remedies are listed in table 1-2.
because the moisture is trapped in the material
and remains there unless the material is
Spray Gun Lubrication.--A spray gun needs
removed. Then repaint the area.
occasional lubrication. To do this, remove the fluid
· Peeling is usually caused by carelessness in
needle packing and soften it with oil. Coat the fluid
needle spring with grease or petrolatum. Figure 1-23
cleaning the surface to be painted. Before paint
shows the location of these parts and the oil hole where
spraying is attempted, the surface to be painted
you place a few drops of light oil.
must be thoroughly cleaned. Cheap spray
materials sometimes result in poor adhesion, but
this should be no problem when standard Navy
paints are used.
· Bleeding occurs when the chemical compounds
of a previous coat discolor the finish coat. When
a paint contains a strong aniline dye (a synthetic
organic dye), bleeding results when another
color is sprayed over it.
SPRAY GUN CARE.--Spray guns (including
paint containers and hoses) must be cleaned
thoroughly after each use. When using solvent in
cleaning spray guns, be extremely cautious because
Figure 1-23.--Lubrication points of a spray gun.