Paint Selection

Acrylics are some of the most durable and accessible paints for exterior application, used by many artists for painting murals due to their lightfastness and weather resistance. They also form an excellent bond to masonrv or cementous surfaces, Oil paints are a poor choice for painting on these surfaces since the alkalinity of concrete can destroy alkyd or oil products. Ethylsilicate paints form an excellent and permanent bond with brick or concrete; however this system can be time-consuming and costly, and a good working knowledge of the materials is required as well. Solvent-based enamels are a good choice for durability, but manufacturer's pigment considerations are usually not the same as with a high-quality artist's acrylic paint.

Golden Artist Colors, Inc. produces several lines of paints that can be used for mural work. Selecting which type of paint to use is dependent on each artist's style and the surface to be painted. GOLDEN Heavy Body, Matte, MSA, Fluid and Airbrush Colors (see below) can all be used for mural work. The artist must determine if the texture will influence the way he or she paints. For example, if painting on brick, it will be tough to get a smooth line on such a textured surface with the Heavy Body Colors as is. They need to be thinned with GAC 200 (which also increases film hardness and potential durability) or the artist may consider switching to the Fluid Colors. The thinner consistency will allow the paint to flow into the crevices of the brick. Mixing Fluids and Heavy Body Acrylics together will produce a consistency similar to house paint, ideal for covering larger areas on most surfaces.
(Refer to the chart above for assistance in selecting a suitable paint line.)

Color selection is especially important to minimize fading of acrylic paints. The GOLDEN Pigment Identification Chart (www.goldenpaints.com/pigments.htm) lists the relative lightfastness and permanency ratings of all our colors. For maximum longevity, we recommend using only colors with a lightfastness rating of I and a permanency rating of Excellent.
(See chart for best recommendations.)

Please note: Cadmium pigments should not be used outdoors as premature fading will occur. Ultramarine Blue and Cobalt Blue should not be used at full strength for outdoor projects. Mixing with other colors or diluting with GOLDEN Gels or Mediums will improve exterior durability.

Although GOLDEN Acrylics are optimized for traditional easel painting, the acrylic resin is somewhat soft for mural work, and should be modified with a harder acrylic medium to maximize durability. Adding GAC-200 also reduces the pigment load of the paint mixture making the paint more binder-rich, which extends exterior lifetime. This is especially important if the artist chooses not to topcoat with a varnish. We suggest blending 1 part GOLDEN GAC 200 for every 2 to 4 parts paint.

For exterior spray application, using GOLDEN Fluid Acrylics thinned with Airbrush Medium will be the most durable option. GOLDEN Airbrush Colors can also be used, but they should be blended with GOLDEN Airbrush Transparent Extender and given a protective varnish to increase durability. In spray application, the GAG 200 is not practical to use as it will thicken the paint and interfere with sprayability. Another approach would be to top-coat the Airbrush Colors with a sprayable isolation coat using a 2:1 mixture of GAC 500:GOLDEN Airbrush Transparent Extender.

Final Coats

A final topcoat will give a mural more durability when exposed to environmental factors. The mural artist has a few choices on how to provide additional protection to the finished mural. One option is to apply an artist-quality varnish that is removable with various solvents, allowing for graffiti removal and general maintenance. GOLDEN MSA Varnish w/ UVLS is such a product, and more complete application information is provided below.

Another choice for protecting the mural is to use some of the various graffiti-resistant finishes that are commercially available. These range from protective wax coatings that are removed with hot water to the 2-component solvent-based polyurethane coatings. They tend to have excellent chemical resistance, so that graffiti can be fairly easily stripped off without harming, the coating. They also have excellent weatherability and thus require less maintenance than some of the other choices. Please note: we have not thoroughly evaluated these systems. As the coatings are not removable should they fail, we suggest artists get all available information from manufacturers or consult mural groups having previous experience using these products to determine the best choice for each specific application.

Listed below are the application recommendations for using GOLDEN MSA Varnish w/ UVLS: We recommend a 2-step system, the first being a permanent isolation coat, followed by GOLDEN MSA Varnish, a removable varnish. The function of the isolation coat is to physically isolate the paint from the removable varnish (which makes varnish removal much easier and safer to the paint surface). An isolation coat also develops a thicker layer of acrylic, which will give better protection and durability and serves to unify the acrylic paint layer.

Isolation Coat Application

Choice of isolation coat should depend upon the artist's application method. Another consideration is the surface texture, as brush-applying the isolation coat and varnish over a highly textured surface can generate foam in the isolation coat. For spray application we recommend a 2:1 mixture of GAC 500 to Transparent Airbrush Extender. For brush application, we recommend a 2:1 mixture of Soft Gel Gloss to water.

Varnish Application.

After the isolation coat is applied and has thoroughly dried (1-2 days, but no more than 1 week for maximum performance), GOLDEN Mineral Spirit Acrylic (MSA) Varnish can be applied. The MSA Varnish w/ UVLS is an excellent choice as a protective finish. This product provides a tough, durable surface that increases resistance to moisture and pollutants. The UV stabilizing system will serve to reduce the destructive potential of ultraviolet radiation from the sun, thus enhancing the life of the system. This varnish is removable in mineral spirits, turpentine and various aromatic solvents, which is a useful property for either graffiti removal or maintenance purposes. Spray application is recommended (1-3 separate coats).

Note: Breathabilty is important to the successful adhesion of acrylic products. If a mural encompasses an entire wall made of a masonry product, it is advisable to apply thin coats of MSA Varnish. This will allow interior condensation and evaporating solvents and outgassings to escape (some artists recommend leaving an uncoated breathing space near the edge of the mural as well). If this is not done, it may lead to premature adhesion failure between the coatings and the substrate. GOLDEN only recommends its MSA Varnishes for exterior work, NOT the Polymer Varnish. Polymer Varnish does not have the same exterior durability as the MSA.