Acrylic paint

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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) or modified with acrylic gels, mediums, or pastes, the finished acrylic painting can resemble a watercolor or an oil painting or have its own unique characteristics not attainable by oil or watercolor.

Acrylics were first available commercially in the 1950s. The first commercially available artist acrylic paints were mineral spirit based paints from a company called Bocour Artist Colors. The waterbased acrylic paints came later and were coined the term "latex" housepaints, although there is not any actual latex from a rubber tree in an acrylic dispersion. Interior "latex" housepaints tend to be a combination of binder (sometimes acrylic, vinyl, pva and others), filler, pigment and water. Exterior "latex" housepaints may also be a "co-polymer" blend, but the very best exterior waterbased paints are 100% acrylic based. Soon after the waterbased acrylic binders were introduced as housepaints, artists (the first artists were Mexican muralists) and companies alike began to explore the potential of the new binders.

Acrylic Artist Paints are their own unique media. They can be thinned with water and made into washes to be used similar to how watercolor paints are used, but the washes are not water sensitive and color lifting techniques are not as easy to do with acrylics as they are with true gum-arabic based watercolor paints.

The main difference of acrylics and oil paints is the inherent drying time. Oils allow for more time to blend colors and apply even glazes over underpaintings, etc. This slow drying aspect of oil can be seen as an advantage for certain techniques, but in other regards it impedes the artist trying to work quickly. The fast evaporation of water from the acrylic paint film can be slowed with the use of retarders. Retarders are generally glycol or glycerine based additives. In the case of acrylic paints, the addition of a retarder slows the evaporation rate of the water, and allows for more water to be added and the paint workable, until the retarder has left the film and the paint layer is dry.

Oil Paints have several disadvantages to acrylics, however. First, they tend to require the addition of a toxic solvent, such as mineral spirits or turpentine to thin the paints and clean up tools, though relatively recently water soluble oil paints have been developed for artist use. Secondly, oil paint films become increasing yellow and brittle, and will lose their flexibility in a few decades. Thirdly, the rules of "fat over lean" must be employed to ensure the paint films are durable.

Oil paint is able to absorb more pigment than acrylic because linseed oil has a smaller molecule than acrylic. Oil has a different Refractive Index than Acrylic dispersions. This changes how light interatcts with the paint films.

Acrylic paints can be made to be either a high gloss, matte or anywhere in between. As with oils, pigment amounts and particle size can alter the paint sheen. Likewise matting agents can be added to dull the finish. Topcoats or vanishes may also be applied to alter sheen.

Acrylic Paint is generally non removable when it is dry. Water or mild solvents do not resolublize it, although isopropyl alcohol can lift some fresh paint films off. Tolunene and Acetone can remove paint films, but they do not lift paint stains very well and are not selective, meaning using a solvent to remove paint will result in removing all of the paint layers, gesso, etc.

Using house-hold latex based paint as a primer for acrylic causes cracking after only a few years, especially if the painting is rolled for storage. Only use a proper, artist grade acrylic gesso to prime your canvas for use with acrylic. Acrylic will not form a stable paint film if it has been thinned with too much water (more than 50% is too much). However, the viscosity of acrylic can successfully be reduced by using suitable extenders that maintain the integrity the paint film (e.g. Golden Acrylic Glazing Medium, Liquitex Gloss Medium and Varnish).

Painters before the 20th Century have mixed their own paints to increase the longevity of the artwork and achieve desired pigment load, viscosity, and control exactly what fillers, if any, are used. While suitable mediums and raw pigments are available for producing your own acrylic paint, due to their fast drying time, hand mixing may not be as practical for the acrylic painter as it may be for an oil painter.

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 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 mediums. 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. Due to acrylic's more flexible nature and far more consistent drying time between colours, the painter does not have to follow the "fat over lean" rule of oil painting, where more medium must be applied to each layer to avoid cracking. While canvas needs to be properly primed and gessoed before painting with oil, acrylic can be safely applied to raw canvas. The fast drying time forces the acrylic painter to work at a much faster pace than an oil painter, or abandon blending all together. While acrylic retarders can slow drying time to several hours, it still doesn't come close to the 3 days or more of open time found in oil paint, and the addition of too much acrylic retarder can prevent the paint from ever drying properly.

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.

[edit] Some popular manufacturers of artist acrylics

Subsidiaries of Col Art, include Winsor & Newton (Finity, Galeria), Liquitex, and Lefranc & Bourgeois acrylics. Daler Rowney is another English manufacturer of acrylic paint.

In the United States, the leading manufacturer of artist acrylic paints is Golden Artist Colors, based in New Berlin, New York. Liquitex also offers a full range of professional paints and mediums, and M. Graham, based in Oregon, also produces a limited range of professional quality acrylics.