|
Paint is the general term for a family of products used to protect and add color to an object or surface by covering it with a pigmented coating. It is also a verb meaning to apply such a
substance.
Paint is very common and is applied to almost every object. It is a method of producing art, an industrial coating, a driving aid (lane markings), a preservative (rust-prone steel auto bodies), on interior walls, on exterior surfaces exposed to weather, and
myriad other uses.
With art, it has also been used for centuries in the creation of great works, such as
Leonardo da Vinci's Mona Lisa and Vincent Van Gogh's Starry
Night.
Components
There are generally three parts to a paint, a solid part, and two liquid parts. Combined, the two liquid parts make up the
medium or vehicle. The solid part is mostly pigments, which are
particles that provide color and also help make the paint opaque. The binder
(usually a natural or synthetic resin) is that part of the vehicle which eventually solidifies to achieve the dried paint film.
The solvent or diluent (often an organic solvent,
or water) is that part of the vehicle that is volatile and does not become part of
the paint film. The major function of the solvent is to thin the paint to make it easy to apply.
After application, the liquid paint solidifies, leaving the binder and pigment as a colored coating. Depending on the type of
binder, this hardening may be a result of processes such as curing (in oil paint, this takes the form of oxidation of linseed oil to form
linoxin), evaporation (most water-based paints are emulsions of solid binders
in water; when the diluent evaporates, the molecules of the binder coalesce to form a solid film), cooling (encaustic, or wax, paints are liquid when warm, and
harden upon cooling), etc.
Art
Since the time of the Renaissance, siccative (drying) oil paints, primarily
linseed oil, have been the most commonly used kind of paints in fine art applications; oil paint is still common today. However,
in the 20th centry, water-based paints, including watercolors and acrylic paints, became very popular with the development of latex and acrylic
pigment suspensions. Milk paints (also called casein), where the medium is derived from
milk, were popular in the 19th century and are still available today.
Egg tempera (where the medium is egg yolk) is still in use as well, as are
encaustic wax-based paints. Guache (pronounced 'gwash' and is a sort of opaque watercolor) was also used in the Middle Ages and
Renaissance for manuscript illumination. The pigment was often made from ground semiprecious stones such as lapis lazuli and the
binder made from either gum arabic or egg white. Guache is also commercially available today.
Poster paint has been used
primarily in the creation of student works, or by children.
Pigment
Pigments, usually insoluble powders, are used both to provide color, and to make paint opaque, thus protecting the substrate
from the harmful effects of ultraviolet light while also increasing a paint's hiding power.
Lead paint: White pigment does not add color, but serves the very important function of increasing opacity
and making the paint resistant to UV radiation. For centuries, the primary white pigment in paints was white
lead (also called lead white), one of the oldest pigments known. The problem with white lead is that it is
extremely toxic. See lead.
It wasn't until the middle of the 20th century that white lead was generally replaced by a less toxic substitute,
titanium white, which was first used in paints in the 19th century. The titanium white used in most paints today
is actually a mixture of titanium dioxide (pure titanium white) and zinc oxide (zinc white). See pigment.
Some newer paints can produce effects where the color changes depending on the angle (orientation) at which it is viewed.
Modern U.S. currency, specifically the newer higher denomination notes, have this effect on them. This effect is produced by
having pigement molecules that are long and thin and are meant to dry in a specific orientation, with different ends of the
molecule being different colors.
Application
Paint can be applied as a liquid, as a solid, or as a gaseous suspension. Techniques vary depending on the practical or
artistic results desired.
In the liquid application, paint can be applied by direct application using brushes,
paint rollers, other
instruments, or body parts. Examples of body parts include fingerpainting, where the paint is applied by hand, whole-body painting (popular in the 1960's avant-garde movement), and cave painting, in which a
pigment (usually finely-ground charcoal) is held in the mouth and spat at a wall (NOTE: DO NOT DO THIS with modern paints, they are highly
toxic and this might cause death or permanent
injury).
Paint may also be applied by flipping or spraying the paint, dripping, or by dipping an object in paint.
As a solid (usually in industrial and automotive applications), the paint is a applied as a very fine powder, then baked at
high temperature. This melts the powder and causes it to adhere (stick) to the surface. The reasons for doing this involve the
chemistries of the paint, the surface itself, and perhaps even the chemistry of the substrate (the overall object being
painted).
As a gas or as a gaseous suspension, the paint is suspended in solid or liquid form in a gas that is sprayed on an object. The
paint sticks the object. The reasons for doing this include:
- the application mechanism is air and thus no solid object ever touches the object being painted;
- the distribution of the paint is very uniform so there are no sharp lines
- it is possible to deliver very small amounts of paint or to paint very slowly;
- a chemical (typically a solvent) can sprayed along with the paint to dissolve
together both the delivered paint and the chemicals on the surface of the object being painted;
- some chemical reactions in paint involve the orientation of the paint molecules.
Similar products
- Wood stain is a product very
similar to paint, except that it is much thinner, and formulated so that the pigment penetrates the surface rather than remaining
in a film on top of the surface. Stain is predominantly pigment or dye and solvent (with little or no binder), designed primarily to add color without providing a
surface coating.
- Varnish and shellac provide a
protective coating without changing the color. They are essentially paint without pigment. Unlike paint, which is opaque, varnish
and shellac are clear or translucent.
- Lacquer is usually a fast-drying solvent-based paint or varnish that produces an
especially hard, durable finish.
- An enamel paint is a paint that dries to an especially hard, usually
glossy, finish. Enamel can be made by adding varnish to oil-based paint.
- Fingerpaint
History
Ancient painted walls, to be seen at Dendara, Egypt, although exposed for many ages to the open air, still possess a perfect
brilliancy of color, as vivid as when painted, perhaps 2000 years ago. The Egyptians mixed their colors with some gummy
substance, and applied them detached from each other without any blending or mixture. They appeared to have used six colors,
viz., white, black, blue, red, yellow, and green. They first covered the field entirely with white, upon which they traced the
design in black, leaving out the lights of the ground color. They used minium for red, and generally of a dark tinge.
Pliny mentions some painted ceilings in his day in the town of
Ardea, which had been executed at a date prior to the foundation of Rome. He expresses
great surprise and admiration at their freshness, after the lapse of so many centuries.
- See also lacquer, varnish
External Links
Other Meanings
Paint is also a military verb meaning to shine a targeting device (laser, radar, etc.) to designate an object
as the target of an attack.
Paint is also a term used in computer
graphics.
A bitmap graphics editor may allow direct painting, e.g. Microsoft Paint, an electronic drawing and painting program.
See also Paint Shop Pro, CinePaint.
"Paint" is a music track by Soul Coughing from their 1996 album Irresistible Bliss.
Paint is a breed of North American horse; they are identified by their coloration, a combination of white and any color, arranged in
large blotches. See American Paint Horse
|