Acrylic Paint - Differences Between Acrylic and Oil Paint

Differences Between Acrylic and Oil Paint

The vehicle and binder of oil paints is linseed oil or another drying oil, whereas water serves as the vehicle for an emulsion (suspension) of acrylic polymer that is the binder in acrylic paint. Thus, oil paint is said to be "oil-based", while acrylic paint is "water-based" (or sometimes "water-borne").

The main practical difference between most acrylics and oil paints is the inherent drying time. Oils allow for more time to blend colors and apply even glazes over underpaintings. 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 regular acrylic paint films can be slowed with the use of acrylic retarders. Retarders are generally glycol or glycerin-based additives. The addition of a retarder slows the evaporation rate of the water.

Oil paints may require the use of solvents such as mineral spirits or turpentine to thin the paint and clean up; these generally have some level of toxicity and are often found objectionable. (Relatively recently, water-miscible oil paints have been developed for artists' use.) Oil paint films can become increasingly yellow and brittle with time and lose much of their flexibility in a few decades. Additionally, the rules of "fat over lean" must be employed to ensure the paint films are durable.

Oil paint has a higher pigment load than acrylic paint. As linseed oil has a smaller molecule than acrylic, oil paint is able to absorb substantially more pigment. Oil provides a different (less clear) refractive index than acrylic dispersions, imparting a unique "look and feel" to the resultant paint film. Not all pigments in oil are available in acrylic. Prussian blue has been recently added to the acrylic colors. Acrylic paints, unlike oil, may also be fluorescent.

Due to acrylic's more flexible nature and more consistent drying time between colors, 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 sized and primed before painting with oil (otherwise it will eventually rot the canvas), acrylic can be safely applied to raw canvas. The rapid drying of the paint tends to discourage the blending of color and use of wet-in-wet technique as in oil painting. While acrylic retarders can slow drying time to several hours, it remains a relatively fast-drying medium, 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. Oil paints fade in color and develop a yellow tint over time; they also begin to crack with age. Acrylic paints have only been in use for approximately fifty years; within that time they have yet to alter in ways seen in oil paints. The changes observed in works done in oil are caused by the paint's binder (linseed oil). Linseed oil dries as an inelastic film. As temperatures rise and fall, this film cracks. Meanwhile, acrylic paint is very elastic, which prevents cracking from occurring. Acrylic paint's binder is acrylic polymer emulsion; as this binder dries the paint remains flexible.

Another difference between oil and acrylic paints is the versatility offered by acrylic paints - acrylic is very useful in mixed media, allowing use of pastel (oil & chalk), charcoal, pen, etc. on top of the dried acrylic painted surface. Mixing other bodies into the acrylic is possible - sand, rice, even pasta may be incorporated in the artwork. Mixing artist or student quality acrylic paint with household acrylic emulsions is possible, allowing the use of pre-mixed tints straight from the tube or tin, so presenting the painter with a vast color range at his or her disposal. This versatility is also illustrated in the wide variety of additional artistic uses that acrylics afford the artist. Specialist acrylics have been manufactured and used for lino block printing (acrylic block printing ink produced by Derivan since the early 1980s), face painting, airbrushing, water color techniques, and fabric screen printing.