High viscosity paint produces paint sag
and orange peel, while low viscosity paint
produces improper flow out and waste of
thinner. To avoid these problems, take care to
measure the proportions of thinner and paint
accurately in a graduated measuring cup.
The temperature at which the spraying is done is
also an important factor in turning out a good job. This
applies not only to the temperature of the shop but also
to the temperature of the vehicle. Shop temperatures
should be maintained at approximately 70°F.
Whenever possible, bring the vehicle into the shop
well in advance of painting so that it becomes the same
temperature as the shop. Spraying paint on a surface
that is too cold or too hot from being in the sun will
upset the flowing time of the material and will cause
orange peel and poor adherence to the surface.
Another important factor in doing a good job is the
thickness of the paint film on the surface. Obviously, a
thick film takes longer to dry than a thin one. As a
result, the paint will sag, ripple, or orange peel. Ideally,
you should produce a coat that will remain wet long
enough for proper flow out. but no longer. The amount
of material you spray on a surface with one stroke of a
gun will depend on the width of the fan. the distance of
the gun from the sprayed surface, the air pressure, and
the amount of thinner used.
In addition, the speed of the spray stroke will also
affect the thickness of the coat. The best procedure is to
adjust the gun to obtain a wet film, which will remain
wet only long enough for good flow out. Get the final
thickness by spraying an additional coat after the first
one has dried.
Nearly all-standard spray guns are designed to
provide optima coverage when held at a distance of 8 to
12 inches from the surface to be painted. When the gun
is held too close, the air pressure tends to ripple the wet
film, especially if the film is too thick. If the distance is
too great, a large percentage of the thinner will be
evaporated in the spraying operation. Orange peel or a
dry film will result. because the spray droplets will not
have opportunity to flow together.
It is imperative, then. to hold the spray gun at the
specified distance from the work. In addition, do NOT
tilt or hold the spray gun at an angle. Also, never swing
the spray gun in an arc. but move it parallel to the work.
The only time it is permissible to fan the gun is when
you want the paint to thin out over the edges of a small
spot. Figure 8-68 shows the method for using a spray
Another ingredient that is sometimes added to the
paint is "drier." This substance causes the paint to set
and dry much more rapidly than normal. Because a
small amount of drier is all that is required, the
instruction on its use must be followed closely. Mixing
paint and adding drier are two critical parts of painting
vehicles. Use of the wrong type of thinner, paint, or
excessive drier will cause the paint to fade. peel, or
blister within a short period of time after completing
Painting instructions for using chemical agent
resistant coating (CARC) and the camouflage painting
of CESE equipment are found in the NAVFAC P-300.
Epoxy fillers (body fillers) are simple to use in that
the body portions do not have to be straightened as
closely as when making repairs without it. By using the
manufacturers instructions, you can apply body filler
over rough places and form it with a body file or
sanding until it conforms to the desired contour.
The advantage of using body filler lies in the fact
that a badly damaged vehicle can be returned to a
like-new appearance quickly and with a limited
amount of metal straightening. Additional, the use of
thinner metals in the bodies of modern vehicles makes
it difficult to reform panels into their original shape.
Should you have an opportunity to use an epoxy
filler. the recommended thickness of the filler should
be kept to approximately 1/8 inch. If more is required.
it should be applied in coats and allowed to dry before
applying the next coat. Do not exceed an overall
thickness of 1/4 inch.
Once a vehicle has been repainted, you will be
required to replace the vehicle identification markings.
The placement of registration numbers and other
equipment markings for identification purposes, as
required by law, are described in the NAVFAC P-300
and COMSECOND/COMTHIRDNCBINST 11200.1.
Civil Engineer Support Equipment (CESE) is
assigned to many locations where atmospheric and
environmental conditions can cause severe corrosion