Electrical contact points and insulators
The original enamel, lacquer, or crackle finish on
all radio, electrical, and sound equipment, unless
existing damage makes refinishing essential
Decorative plastic, such as tabletops
SURFACES TO PAINT
The Navy uses a variety of metal, metal
compounds, and synthetic materials to build a ship or
boat. Each type of surface requires special preparation
and special primers and paint to extend its life cycle. In
this section, you will learn about various surfaces and
the procedures needed to maintain them properly.
Aluminum Surfaces
Aboard ship, aluminum surfaces are a special
problem. If they’re not treated properly, corrosion
results. Corrosion is greater when dissimilar metals (for
example, aluminum and steel) are in contact with each
other and are exposed to seawater. Seawater is an
electrolyte (an electrical conductor). As such, the
seawater causes an electrical current to flow between
the steel and aluminum surfaces, resulting in galvanic
corrosion of the aluminum. The first sign of aluminum
corrosion is a white, powdery residue in the area where
the two dissimilar metals make contact. Later, the
aluminum surface is pitted and scarred. Finally, there is
a complete deterioration of the aluminum area. Holes in
aluminum plate enlarge and screws, bolts, or rivets pull
out, or they may even disintegrate.
Before joining aluminum to another metal, give
each surface a pretreatment formula and two coats of
primer formula.
NOTE
Never use red lead as a primer on aluminum.
If the joint is exposed to the weather, use insulation
tape between the two surfaces, and fill the joint with
caulking compound. When aluminum is joined to
wood, give the wood one coat of phenolic varnish.
Replace any missing fasteners (screws, bolts, rivets, and
so on) with items of the original type. (NOTE:
Replacements of stainless or galvanized steel may be
used.) When painted, the best way to prepare the
aluminum surface for repainting is to use hand scrapers,
hand and power wire brushes, or fine grit sandpaper. Be
careful if you use a power sander to prepare the
aluminum surface for repainting.
NOTE
Never use scaling hammers on aluminum.
Steel Surfaces
When painting a steel surface, preparation of the
surface is important. Steel surfaces must be completely
free of rust, loose paint, dirt, scale, oil, grease, salt
deposits, and moisture before they are painted. Old
paint in good condition is an excellent base for
repainting. Smooth, thoroughly clean, and dry the
surface before applying new paint.
In touch-up painting (when only small areas or
spots need repainting), remove old paint to the edges of
the spot or area until an area of completely intact paint is
reached. (NOTE: This area must be free of rust or
blisters underneath the paint.) Feather the edges of the
remaining paint.
When completely reworking an old painted surface,
take the old paint down to the bare metal. Then apply a
primer before painting. Never leave a base metal surface
exposed overnight. Always put on a primer coat before
you secure for the day.
Fillers
Fill holes, dents, and cracks in all surfaces and
open-grained woods before they are finished. Putty,
wood fillers, and even sawdust mixed with glue can be
used on wood. Use epoxy fillers on steel and aluminum
surfaces. The method you use varies with the type of
filler. Therefore, follow the instructions carefully.
Allow all fillers to dry and then sand them smooth
before you apply the first finishing coat.
Paint and Varnish Removers
Paint and varnish removers are most often used on
wood surfaces. However, you can use paint and varnish
18-15
Student Notes:
