2-11. Interior Protective Coatings. There are many types of interior coatings available. These
coatings are decorative and designed for use on certain types of surfaces.
a. Types of Surfaces.
(1) Wood. Alkyd paints for interior wood surfaces comes in flat, semigloss, and gloss paint
finishes. Some paints come in tints as well as white. Alkyd enamels have a good hiding quality and
flow smoothly. They offer durable to heavy-duty protection for wood, metal, drywall, and plaster.
Latex paint is washable, and the finish may be gloss, semigloss, or flat. Some latex paints come in tints
as well as white, and the tinted paints have a low-luster finish.
For interior woodwork that is to have a natural finish, you should prime and seal it with a ready-mixed
varnish or spraying lacquer that is diluted with the recommended thinner. The varnish or lacquer is
applied after the drying oil and filler have been put on and are dry enough to receive the primer-sealer.
When interior woodwork is stained, shellac varnish is used as a primer-sealer to avoid the bleeding of
aniline (synthetic organic dye) stains. You may use varnish or lacquer as a primer-sealer on other types
(2) Metal. When you paint interior metal surfaces, you should use a primer, at least one
body coat, and a final coat. If more coats are applied, the additional coats are called body coats.
(3) Masonry. Interior masonry surfaces may be body-coated and final-coated with alkyd
enamel or polyurethane paint that is used on wood or metal surfaces. Final coats are selected based on
the color and the type of finish desired. For high-traffic areas, latex-based paints that will give a flat or
an eggshell finish are available. When you desire a gloss or semigloss finish, you will generally resort
to other alkyd enamels or latex paints.
b. Types of Coatings. Several of the most commonly used coatings for interior surfaces are
listed below. Notice that some are used on exterior surfaces and interior surfaces. New paints are being
developed all the time, and you should read current publications that deal with protective coatings.
(1) Interior cold-water white paint. This white paint comes in powdered form and is mixed
with cold water. The paint is available in white and tints. This paint is primarily intended to cover
primed, wet (damp) walls and other masonry surfaces. It is not satisfactory for surfaces that are
continually damp because of its susceptibility to mildew. When repainting surfaces, you must remove
calcimine and loose or powdering oil-paint coatings.
(2) Primer-sealer floor lacquer. This lacquer is intended for sealing clean, wooden floors that
have been sanded. By sealing a newly sanded, close-grained or open-grained floor, you help fill the
wood pores and provide a good foundation (priming coat). The primer-sealer reduces the tendency of
the finished surface to mar, integrates the filler and the wood, and smoothes the surface.
(3) Fume- and heat-resistant white enamel. This enamel is used in chemical laboratories,
dairies, refrigerator rooms, sewage-disposal plants, and areas subjected to