Acrylic paintings now make up a significant part of the permanent collections of museums and art galleries. Artists’ acrylic paint was introduced in the 1950s and since then has dominated the arts and crafts market. In addition, it has been accepted by artists as a viable alternative to oil paint. Unlike oil paints, which have existed for centuries, Acrylic paints are a relatively new medium. Once dry, acrylic paint is not water-soluble and will usually be dry within 30 minutes of application, whereas oils do not become dry to the touch for 48 hours. Most acrylic paint used by artists is water-based. There is a form of acrylic paint that is solvent based, but it is not in general use by artists. A variety of additives can be added to the acrylic paint to make them easier to work with or to give the texture wanted by the artist. Examples of these are thickeners, stabilizers, preservatives, and merging solvents.
Because it is a 20th century product, artists don’t have centuries of experience to tell what effect aging may have on an acrylic painting. Acrylic colors retain their original brilliance as long, or longer, than traditional oil paints, and they are much less delicate and prone to damage by UV radiation than watercolors and other water-based paints. The surface of a finished acrylic painting does not seem to become brittle or yellow with age, but remains flexible, insoluble and stable.
The behavior of acrylics as a painting medium and their physical and chemical properties are different from oil paint and merit different strategies in caring for acrylic paintings. Some traditional conservation methods can in fact cause damage to the acrylic paintings. The aging characteristics of acrylic paintings are just beginning to be understood. It is known that aging may cause some acrylic paintings to form a grey veil on their surface or develop yellow discoloration. The soft film formed by acrylic paint will easily abrade or dent with just fingernail pressure. This type of damage can ruin the appearance of paintings that should display a perfect surface. Because Acrylic paint stretches when exposed to heat and cold, Acrylic paintings are expected to develop fewer cracks than oil paintings when they age. Acrylic paintings can withstand much greater forces without breaking. Cracks can form in acrylic paintings however. When exposed to sub-zero temperatures, acrylics become increasingly brittle and crack so don’t store your acrylic paintings in a freezer!
Acrylic paintings have unique qualities that need diligent preventive care to avoid long-term damage. Acrylic paint attracts and holds dirt and is difficult to clean. Varnishing to protect the paint is not a perfect solution either. It is imperative to store acrylic paintings in a dust free, smoke free location to reduce the amount of dirt accumulated. It is also important to keep the display or storage temperature below standard room temperatures to reduce further softening of the paint film. One might have to accept that acrylic paintings will experience some visual change due to dirt as time goes on. Avoid handling the painting’s surface directly. Erosion from scuffing or touching the paint surface can damage or alter the appearance of the work significantly. This is because skin oils are acidic and can damage the artwork over time. Dust and dirt are a particular hazard. Acrylics can also pick up mold residue if they are stored in a warm climate like a bathroom or locker room, or even a kitchen.
At present, there is no completely satisfactory solution to the problem of cleaning acrylic paintings. Removal of the top most dirt layer is perceived to be easier on a varnished painting. Varnishes provide surface protection from abrasion, dust and dirt. Varnishing acrylic paintings has problems attached to it. Natural varnishes, such as dammar, will yellow in time and the solvent used in their removal will dissolve or soften the acrylic paint layer, thus damaging your painting. A water-soluble varnish may be an answer; however, this is still being researched by manufacturers to see what long-term effects may take place. Instead, it is important to store acrylic paintings in a dust free environment to reduce the amount of dirt deposited while keeping the display or keep the temperature below standard room temperatures to reduce further softening of the paint film.