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Paint is a substance, usually a liquid, that is
applied to surfaces as a protective coating or
decoration. Opaque paints color and completely
hide the material under them. Translucent paints
coat the material without hiding its
characteristics. Almost all solid materials
can be painted. Paints are used as protection
against rust, weathering, and chemical
corrosion. Brightly colored paints are used as
warnings, identifying, for example, pipes that
are dangerously hot. Liquid paints have two main
parts; a pigment and a vehicle. Pigments are
finely ground powders that give the paint color
and opacity. In addition, pigments may also
affect the texture, water resistance,
penetration and wearing characteristics of a
paint. Pigments remain in solid form in a paint;
they do not dissolve in the vehicle which is a
liquid that act as a base for the pigment. This
means the pigment is merely suspended in the
vehicle. The vehicle usually consists of a
binder and a solvent. The binder is the part of
the vehicle that holds the paint film together
and makes it adhere to a surface. The solvent,
also called thinner, is on the other hand a
substance that reduces the consistency of paints
so that the paints can be applied or removed
easily. Solvents are usually volatile and
evaporates completely leaving a solid film of
pigment and binder on the surface. Turpentine,
mineral spirits, solvent naphtha, grain alcohol
and water are common paint solvents. Solid, or
powder paints differ from other kinds in that
they contain no vehicle.
The earliest known use of paint was in the
cave dwellings of prehistoric men 50,000 years
ago. The cave dwellers used red, yellow and
black pigments with binders of animal fat. The
Egyptian had seven colors, including blue and
green, and a variety of binders. They are
credited with the discovery of varnish. The
Greeks and Romans made their contribution by in
creasing the number of pigments available. The
use of paints declined during the Middle Ages,
but was revived during the Renaissance period,
and has been increasing ever since. In the early
days, for example, it was a mark of wealth to
have a painted house. Today the majority of
homes are painted; inside and outside.
Until the late 19th century, pigments and
binders had to be mixed by the painter.
Ready-mixed paints were developed in the 1860s
and gained wide acceptance in the 1880s. Since
that time improvements in the quality of
ready-mixed paints have been made continuously.
By the mid-20th century, the development of
synthetic resins and rubbers caused a sudden
increase in the numbers and kinds of paints
available. The synthetic-based paints often did
the job faster, better and more easily than
earlier paints. Some special purpose paints such
as antifouling paint for the bulls of ships and
fire-resistant paint, were developed during
World War II especially for military
applications. Among the many other types of
synthetic-based paints were latex household
paints for both interior and exterior use;
acrylic automobile enamels; heat-resistant
paints; fluorescent paints; and powder paints. |
