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). 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. Acrylic paints can achieve an oil-paint-like effect, and do so in much less time. Though applied to look like oil paints, acrylics are somewhat limited due to the superior colour range of oil paints, 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 .
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. Mediums 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 paintings, ideally, should be recognized as being as different from oil paintings as watercolors are, in other words, as a distinct art medium with its own advantages as well as limitations, rather than as a stand-in for another meduim. 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 watercolour) 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.