Careful selection of surface for mural work should be done first. The ideal situation would allow the artist to work on a smooth surface.
If the mural is not an existing structure, but will be constructed specifically for your artwork, carefully consider the choice of building materials to be painted. For example, there are many plywood grades available. MDO plywood (Medium Density Overlay), often referred to as "sign painters board", is a highquality plywood that is made to be used outdoors. It could also be attached to a wooden, metal or brick wall before painting a mural. This would offer the artist a surface that is clean, smooth and can be painted indoors in the studio, rather than on a scaffold at the mural site.
Painting an Existing Surface
If factors dictate painting directly onto a preexisting surface, preparation is a major factor in the longevity of the mural.
Surface Cleaning Considerations
The artist must be concerned with the nature of the surface to be painted. If the surface is already painted, then consider what kind of paint it is and its physical condition (the artist should realize that any surface that still has the previous coating on it will not be as permanent as one that has been completely stripped and freshly coated). If the paint is a waterbased polymer, chances are good that the GOLDEN paints will adhere sufficiently. If it is a high gloss oil paint (or of unknown materials), then it must be abraded (or removed) for good adhesion. If the existing paint film is deteriorating, then it is best to have it removed (sandblasted, powerwashed, scraped, etc.). It is critical to wash any painted surface, even a newly painted surface, with soap and water prior to application of acrylic products. A major coatings manufacturer states that as much as 80% of all coatings failure can be directly related to insufficient surface preparation.
Previously painted high gloss surfaces can be cleaned and dulled in one step by using a household abrasive cleaner. Wash off completely with clean water.
Mold and Mildew
Mold and mildew must be removed by hand scrubbing with a mixture of 1 part household bleach to 3 parts water. CAUTION: Never add ammonia or ammonia based cleaners to bleach! Wear goggles and protective equipment while cleaning. After scrubbing with a brush, allow the solution to sit on the surface for 10 minutes before thoroughly rinsing off with clean water.
Cracks and Grooves
If there are cracks and grooves in the substrate, the method for filling and smoothing these gaps will depend on the nature of the substrate itself. Artists should consult an area architectural coatings store for recommendations on the best product available.
Priming the Surface
Once the surface has been cleaned, a primer coat will give better adhesion for the paint.
One key feature to look for in a primer is whether or not it can be painted over by latex (waterborne) paints. This should ensure that the primer will be a compatible surface for the adhesion of GOLDEN waterborne acrylics.
To determine the best primer for a specific surface, we suggest artists contact a local supplier of architectural coatings. Such companies have extensive experience with priming the broad spectrum of building supplies, and typically have specific primers for the surface the mural is to be painted on. Their recommendations will also take the environmental concerns of the area into account. We have found that architectural and maintenance paints are competitively priced, meaning that a product that costs more than a similar product will typically perform better as well.
When painting on brick, concrete, or other masonry surfaces, it is recommended to also use a Masonry Conditioner that can be purchased from a commercial coatings supplier.
Acrylics are some of the most durable paints for exterior application.
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 masonry 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 good working knowledge of the system 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 highquality artist's acrylic paint.
Golden Artist Colors produces several lines of paint 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 High Flow Acrylics 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 brushed on 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. (Refer to the chart below for selecting a suitable paint line).
Use this Quick Reference Chart for choosing GOLDEN Acrylic Paints for Mural Use.
|Golden Product (not modified)||Smooth Textured Surface||Moderately Textured Surface||Heavily Textured Surface|
|Heavy Body Acrylics||✔B|
|High Load Acrylics||✔||✔|
|✔||Can be used for this surface||B||Best recommendation for particular surface|
Note: Mixing is recommended with the GAC 200 to increase adhesion and durability, which will thin thicker viscosity products.
Choosing the Right Colors
Color selection is especially important to minimize fading. The GOLDEN Pigment Identification Chart 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. Please note: Cadmium pigments should not be used outdoors, as premature fading will occur.
GOLDEN Suggested Color List for Exterior Murals
Although GOLDEN uses only the most permanent pigments available within each chemical classification, we have compiled this list of the best pigment choices for use on an exterior mural. Application of isolation coats and a suitable varnish or topcoat is highly recommended.
BEST PIGMENTS - The most stable GOLDEN colors for exterior use.
GOOD PIGMENTS - Stable colors, but avoid thin layers or glazes for minimal color shift.
Increasing the Durability of the Paint System
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. To improve the exterior durability of the paints, blend in 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 High Flow Acrylics can also be used, but they should be blended with GOLDEN Airbrush Transparent Extender and given a protective finish to increase durability. In spray application, the GAC 200 is not practical to use as it will thicken the paint, and interfere with sprayability. Another approach would be to topcoat the High Flow Acrylics with a sprayable isolation coat using a 2:1 mixture of GAC 500:GOLDEN Airbrush Transparent Extender.
Murals and Architectural Applications
Any paint or topcoat applied to a building, including interior or exterior walls, is considered an architectural coating and subject to regulations limiting the amount of VOC's (Volatile Organic Compounds) a product may have. Murals painted directly onto these surfaces, therefore, will fall under the same guidelines and all paints, mediums, and varnishes being used will need to comply with the same rules. Containers that are 1 Liter (1.05 Quarts) or less in size, however, are currently exempt from these requirements.
Murals Painted Directly onto Architectural Surfaces
PLEASE NOTE the Following Restrictions
Murals Painted onto Canvas, Panel, and Other Supports
A final topcoat gives the mural more durability from the 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. As we have not thoroughly evaluated these systems, we suggest you get all the information required from the manufacturers, and/or any mural groups that may share previous experiences, to determine the best choice for your specific application.
Application recommendations for 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.
Note: Breathability 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 surface.
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.
Temperature, precipitation, and humidity should be considered during application.
High humidity can also effect the mural's drying times similar to the conditions cited above for precipitation. As the relative humidity climbs above 70%, more caution needs to be taken.
Primer - a coating that seals and prepares the surface to accept the subsequent paint layers.
Lightfast - ability to withstand color change due to exposure to light.
Use this Mural Procedure Quick Reference to decide course of action.
|Mural Surface||Step 1: Cleaning||Step 2: Priming||Step 3: Paintng||Step 4: Isolation & Varnish Coatings|
|Bare Wood||None||Knots and pitch streaks should be sanded and spot-primed. Apply primer coat (suitable for latex)||Apply Golden Acrylic Paints to surface||Apply isolation coat. Leave to dry thoroughly (at least 48 hours). Apply Golden MSA Varnish* or suitable alternative.|
|Previously Painted Wood||Remove any loose material, power-wash clean. Abrade non-water-based coatings||Inspect knots for staining, sand and spot-prime as needed. Apply primer coat (suitable for latex)||Apply Golden Acrylic Paints to surface||Apply isolation coat. Leave to dry thoroughly (at least 48 hours). Apply Golden MSA Varnish* or suitable alternative.|
|Bare Masonry||None||Apply Masonry conditioner. Apply water-based latex primer||Apply Golden Acrylic Paints to surface||Apply isolation coat. Leave to dry thoroughly (at least 48 hours). Apply Golden MSA Varnish* or suitable alternative.|
|Previously Painted Masonry||Remove any loose material, power-wash clean. Abrade surface||Apply Masonry conditioner. Apply water-based latex primer||Apply Golden Acrylic Paints to surface|
|Bare Metal||Remove any grease, dirt, solvents. Abrade surface.||Apply alkyd or latex-based primer||Apply Golden Acrylic Paints to surface|
|Previously Painted Metal||Remove any loose material, rust, grease, dirt. Abrade surface.||Apply alkyd or latex-based primer||Apply Golden Acrylic Paints to surface|
|For complete Varnish procedures, refer to the Varnishing page.|
The above information is based on research and testing done by Golden Artist Colors, Inc., and is provided as a basis for understanding the potential uses of the products mentioned. Due to the numerous variables in methods, materials and conditions of producing art, Golden Artist Colors, Inc. cannot be sure the product will be right for you. Therefore, we urge product users to test each application to ensure all individual project requirements are met.