by the user, the cost, and the length of time the appearance must remain satisfactory. The materials
mentioned in the previous sections on pigments (paragraph 2-5) and vehicles (paragraph 2-6) are used to
make many different types of organic finishes for decorative and protective purposes; however, some of
the most common types are oil-based paint, enamel, lacquer, water-based paint, varnish, shellac, and
a. Oil-Based Paint. Oil-based paint consists principally of a drying oil (usually linseed) mixed
with one or more pigments. Oil-based paint may be modified by the addition of varnish. The exterior
surface of houses and metal surfaces in atmospheric exposure will usually be coated with oil-based
paints. The vehicle in these paints can be a combination of raw and processed oils, or it may be a single
oil, depending on the properties required in the paint. The pigments and their quantities are usually
selected on the basis of cost and their ability to impart the desired application properties, such as
durability, economy, brushability, and color. Oil-based paints are characterized by easy application,
slow drying, and a good ability to wet the surface being coated. They normally chalk in such a manner
that permits recoating without costly surface preparation.
b. Enamel. Enamel is a paint which is characterized by the ability to form an especially smooth
film. By definition if the pigment product is relatively easy to brush and is used on large areas such as
walls or structural steel, it is called a paint. If it is relatively fast drying, levels out to a smooth, hard
finish, and is used on relatively small areas or smooth substructures such as woodwork, it is called an
enamel. Enamels are commonly thought of as pigmented, varnish-vehicle paints that have good flow
and leveling properties and dry rapidly (4 to 16 hours) at normal temperatures. In general, the ability of
enamel to wet the surface and coat surface irregularities is not as good as oil-based paints. Enamels
generally fail by chipping, cracking, blistering, or similar action as a result of a gradual decrease of
elasticity that comes with age. Enamel films are generally harder, tougher, and more resistant to
abrasion and moisture penetration than oil-based paints. Enamel may be applied by brushing, spraying,
or dipping. When applying enamel by brush, flow the paint on the surface rather than brushing it out as
with oil-based paints. Enamels of the baking type are widely used in industrial finishing.
c. Lacquer. Lacquer differs from oil-based paint and enamel because it contains some type of
resin as a vehicle. Lacquer is normally applied by spray since most types dry too fast for brushing.
Lacquer is usually applied by a series of thin films. You can obtain a hard, brittle coating; a tough,
elastic coating; a high or low gloss film; and many other variations by the proper choice of lacquer
materials. The durability of lacquer finishes on some makes of automobiles is proof that good
protection is given by lacquer. Vinyls and rubber-based solutions (paints) are technically lacquers.
They have outstanding durability in many types of exposures.
d. Water-Based Paint. Water-based paint is distinctly different from other paint because the
vehicle is an emulsion of binder and water. The emulsion technology is promising for VOC compliance
because water is not a restricted solvent. Water-based paints have the advantages of easy application,
drying by evaporation of water, easy reduction of viscosity with water, and easy cleaning of tools with
soap and water. This type of paint was originally used as an interior coating; however, with product
advances in water-based paints and the increased concern over fire prevention, its usage has broadened