section, well cover some of the most commonly
OIL-BASED PAINTS. Oil-based paints
consist mainly of a drying oil (usually linseed) mixed
with one or more pigments. The pigments and
quantities of oil in oil paints are usually selected on
the basis of cost and their ability to impart to the paint
the desired properties, such as durability, economy,
and color. An oil-based paint is characterized by easy
application and slow drying. It normally chalks in such
a manner as to permit recoating without costly surface
preparation. Adding small amounts of varnish tends to
decrease the time it takes an oil-based paint to dry and
to increase the paints resistance to water. Oil-based
paints are not recommended for surfaces submerged
ENAMEL. Enamels are generally harder,
tougher, and more resistant to abrasion and moisture
penetration than oil-based paints. Enamels are
obtainable in flat, semigloss, and gloss. The extent of
pigmentation in the paint or enamel determines its
gloss. Generally, gloss is reduced by adding lower cost
pigments called extenders. Typical extenders are
calcium carbonate (whiting), magnesium silicate
(talc), aluminum silicate (clay), and silica. The level
of gloss depends on the ratio of pigment to binder.
EPOXY. Epoxy paints area combined resin and
a polyamide hardener that are mixed before use. When
mixed, the two ingredients react to form the end
product. Epoxy paints have a limited working, or pot,
life, usually 1 working day. They are outstanding in
hardness, adhesion, and flexibility-plus, they resist
corrosion, abrasion, alkali, and solvents. The major
uses of epoxy paints are as tile-like glaze coatings for
concrete or masonry, and for structural steel in
corrosive environments. Epoxy paints tend to chalk on
exterior exposure; low-gloss levels and fading can be
anticipated. Otherwise, their durability is excellent.
LATEX. Latex paints contain a synthetic
chemical, called latex, dispersed in water. The kinds
of latex usually found in paints are styrene-butadiene
(so-called synthetic rubber), polyvinyl acetate (PVA
or vinyl), and acrylic. Latex paints differ from other
paints in that the vehicle is an emulsion of binder and
water. Being water-based, latex paints have the
advantage of being easy to apply. They dry through
evaporation of the water. Many latex paints have
excellent durability. This makes them particularly
useful for coating plaster and masonry surfaces.
Careful surface preparation is required for their use.
RUBBER-BASED. Rubber-based paints are
solvent thinned and should not be confused with latex
binders (often called rubber-based emulsions).
Rubber-based paints are lacquer-type products and
dry rapidly to form finishes highly resistant to water
and mild chemicals. They are used for coating exterior
masonry and areas that are wet, humid, or subject to
frequent washing, such as laundry rooms, showers,
washrooms, and kitchens.
PORTLAND CEMENT. Portland cement
mixed with several ingredients acts as a paint binder
when it reacts with water. The paints are supplied as a
powder to which the water is added before being used.
Cement paints are used on rough surfaces, such as
concrete, masonry, and stucco. They dry to form hard,
flat, porous films that permit water vapor to pass
through readily. When properly cured, cement paints
of good quality are quite durable. When improperly
cured, they chalk excessively on exposure and may
present problems in repainting.
ALUMINUM. Aluminum paints are available
in two forms: ready mixed and ready to mix.
Ready-mixed aluminum paints are supplied in one
package and are ready for use after normal mixing.
They are made with vehicles that will retain metallic
brilliance after moderate periods of storage. They are
more convenient to use and allow for less error in
mixing than the ready-to-mix form.
Ready-to-mix aluminum paints are supplied in
two packages: one containing clear varnish and the
other, the required amount of aluminum paste (usually
two-thirds aluminum flake and one-third solvent).
You mix just before using by slowly adding the
varnish to the aluminum paste and stirring. Ready-
to-mix aluminum paints allow a wider choice of
vehicles and present less of a problem with storage
stability. A potential problem with aluminum paints is
moisture in the closed container. When present,
moisture may react with the aluminum flake to
form hydrogen gas that pressurizes the container.
Pressure can cause the container to bulge or even pop
the cover off the container. Check the containers of
ready-mixed paints for bulging. If they do, puncture
the covers carefully before opening to relieve the
pressure. Be sure to use dry containers when mixing
In contrast to paints, varnishes contain little or no
pigment and do not obscure the surface to which
applied. Usually a liquid, varnish dries to a hard,