Acrylic paint is fast-drying paint containing pigment suspended
in an acrylic polymer emulsion. Acrylic paints can be diluted
with water, but become water-resistant when dry. Depending
on how much the paint is diluted (with water), the finished
acrylic painting can resemble a watercolor or an oil painting.
Acrylics were first available commercially in the 1940s,
although experimental forms of acrylic resin paints had been
developed as early as the 1920s in the U.S. and earlier in
Germany. The first commercially available acrylic paints were
actually oil compatible.
Acrylics are sometimes used in place of watercolors because
acrylics dry closer to the desired color (slightly darker,
usually) while watercolors dry lighter (and often unpredictably,
especially for beginning artists).
Acrylics are often used as an alternative to oil paints because
acrylics dry much faster (usually within an hour or even as
little as less than a minute, depending on brand and thickness
of application). On the otherhand, oil paints, which consist
of pigment suspended in an oil (usually linseed, or other
natural oil) base, can take a very long time to dry: a few
weeks or as long as several months. Though applied to look
like oil paints, acrylics are somewhat limited due to the
superior color range of oil paints,[citation needed] and the
fact that acrylic paints dry to a shiny, smooth effect—not
surprising since acrylic paints are, basically, plastic. Accordingly,
acrylic paint cannot be removed with turpentine, mineral spirits
(also known as white spirits), ammonia, or rubbing alcohol.
Another one of the disadvantages of this medium is that paintings
can crack and be corrupted much sooner than with oil. Most
painters outside of the 20th Century have mixed their own
paints to increase the longevity of the artwork.
Acrylic painters modify the appearance, hardness, flexibility, texture, and other characteristics of the paint surface using acrylic mediums. Watercolor and oil painters also use various mediums, but the range of acrylic mediums is much greater. Acrylics have the ability to bond to many different surfaces, and mediums can be used to adjust their binding characteristics. Acrylic paint can change the sheen from gloss to matte, or can add iridescence or texture to the surface. They can also be used to build thick layers of paint: gel and molding paste mediums are sometimes used to create paintings with relief features that are literally sculptural.
Acrylic paints are the most commonly used in grattage (q.v.).
Acrylic paintings should ideally be recognized as being as different from oil paintings. Acrylic paintings are a distinct art medium with its own advantages as well as limitations, rather than as a stand-in for other meduims. There are techniques which are available only to acrylic painters, as well as restrictions unique to acrylic painting. Therefore, judging an acrylic painting as though it were an oil painting (or a watercolor) is not always appropriate.
Although the permanency of acrylics is sometimes debated by conservators, they appear more stable than oil paints. Whereas oil paints normally turn yellow as they age/dry(oxidize), acrylic paints, at least in the 50 years since invention, do not yellow, crack, or change.
