You can also test the paints you plan on using in an inconspicuous location on the fiberglass body. We suggest the "Cross-hatch Adhesion Test" in which the paint films are scored with a razor knife. In a space of approximately 2 square inches, score a series of parallel lines about 1/8" apart. Then score another series (perpendicular) across the first ones, creating a cross-hatch pattern of little squares. Finally, take a piece of ordinary masking tape, burnish it on the section, and lift off straight up from the surface. If there are no squares that lift off, then you have excellent adhesion between all layers. If a few squares come off but the majority remains, you may have sufficient enough adhesion, especially after the sculpture is clear coated. If most or all of the squares come off, this suggests poor adhesion. Note where the failure occurred. Did the primer come off of the fiberglass? Did the paint come off of the primer coat? This will indicate whether or not the primer is suitable or if it needs to be sanded to accept the acrylic paints.
Sand the surface in a circular motion with sandpaper grits between 220 and 440. The surface should be wiped down with a damp rag frequently and inspected for glossy spots. Once there are no noticeable areas of gloss, give a final wipe-down and then degrease (below).
In general, most GOLDEN Acrylic products can be used for this application. GOLDEN Heavy Body, Fluid, Matte, Matte Fluid and High Load Acrylics, High Flow Acrylics, and Iridescent/Interference Colors should all have adequate adhesion. However, to increase adhesion and physical hardness of the acrylics, blend between 10 to 75% GAC 200. This is the hardest acrylic medium we produce; it extends paints while increasing durability.
Other brands of acrylics can be used; however, we cannot offer assistance for their use, as we do not know what their adhesion, permanence and durability may be. We suggest contacting the manufacturer of these products before embarking on the project.
Other kinds of paints, such as housepaints, oil paints, automotive, acrylic enamels, etc., may also be used for this application. Because of the infinite factors involved with using these products, we suggest contacting the manufacturer before use on the project.
Certain pigments are more fugitive than others, meaning that they are more prone to color fades and changes from exposure to sunlight and exterior environments. GOLDEN only uses Lightfast rated I & II pigments, with the exception of the Fluorescent products. Using anything less than Lightfastness I pigment may result in rapid color shifts when exposed to sunlight. Lightfastness information is available for GOLDEN products upon request. Even the use of GOLDEN Hard MSA Varnish (with UVLS) cannot insure fugitive materials (this includes papers, dyed fabric, plastics, etc.) from some degree of fading.
Some pigments react to the combination of sunlight, temperature, moisture and acidity present in outdoor areas. Cadmiums and Ultramarine Blue are pigments to avoid outdoors, especially when used in glazes.
GOLDEN Suggested Color List for Exterior Sculpture
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 MSA Varnish layers is highly recommended.
BEST PIGMENTS - The most stable GOLDEN colors for exterior use.
Bismuth Vanadate Yellow
Burnt Umber Light
Chromium Oxide Green
Chromium Oxide Green Dark
Cobalt Teal (color discontinued in 2012)
Cobalt Titanate Green (color discontinued in 2012)
Iridescent and Interference Colors (except Iridescent Bright Gold)
Phthalo Blue GS
Phthalo Blue RS
Phthalo Green BS
Phthalo Green YS
Pyrrole Red Dark
Pyrrole Red Light
Terre Verte Hue
Transparent Brown Iron Oxide
Transparent Red Iron Oxide
Transparent Yellow Iron Oxide
Van Dyke Brown Hue
GOOD PIGMENTS - Stable colors,
but avoid thin layers or glazes for
minimal color shift.
Cerulean Blue Deep
Naples Yellow Hue
Hansa Yellow Opaque
Special Application Requirements
Some artists have had questions about using materials other than artist products for applications ranging from imbedding objects in acrylic gels, riveting metal platelets, creating unusual textures, and unique paper and fabric collage applications. Most of these applications can be done with GOLDEN Gels and Mediums (most commonly using Soft Gel Gloss as a glue); however, certain objects should be attached with more commercially acceptable methods. 2-part epoxy glues are best for joining non-porous materials together. Acrylics dry from evaporation, and thus would not be acceptable for materials that did not allow some airflow or have some porosity to them. Contact the GOLDEN Technical Support Department if you require some specific recommendations.
Thick layers of gel mediums and paints require a minimum of 48 hours to dry. Humidity, temperature and airflow are important factors for the drying of acrylics. Be sure to allow for this curing process before final varnishes are applied, as trapped moisture and other additives can be the cause for early delamination.
Sealing the Surface for Clearcoat/TopcoatApplication
Once the piece is thoroughly dry, sealing the surface will even out any differences in absorbency and make the application of a protective clearcoat or topcoat easier. It will also act as a barrier or Isolation Coat between the painted artwork and the final protective coating.
Recipes and Application
For brush applications we recommend using Soft Gel (Gloss) thinned 2:1 with water (two parts Gel to one part water). Soft Gel has the least tendency to foam and when mixed in a 2:1 mixture with water is the consistency of heavy cream, making for easy application. When combining the Soft Gel with water, mix slowly and thoroughly so no foam is generated in the mixture. Mixing this one day before application will allow any bubbles or foam to dissipate.See our video Creating a Brushable Isolation Coat for more information.
Applying the Isolation Coat with a soft brush that holds a good amount of material, holds its shape and leaves no brushstrokes is ideal. Thin bristled synthetic brushes often leave the least amount of brushstroke lines. One to two coats are required, although at times, more may be necessary. Any visible brushstrokes can be negated by brushing subsequent coats perpendicular to the prior coat. Utilizing the textures and borders within the piece can also assist in creating a less visible isolation coat. See our video Brush Application of an Isolation Coat for more information.
To determine if you need to apply a second or third layer of isolation coat, once the first coat is dry look at the piece at an angle for an even sheen. If the surface is blotchy or uneven, then another coat should be applied
If you want to spray and have access to an airbrush or spray gun, then use 2 parts GAC 500 to 1 part Airbrush Transparent Extender. Two to three coats should provide substantial coverage although more may be applied if necessary.
To determine if you need to apply a second or third layer of isolation coat, once the first coat is dry look at the painting at an angle and an even sheen should indicate an even surface ready for varnish. If the surface is not even then apply another coat.
Always let the isolation coat dry for a minimum of one day before applying a topcoat. If there is a time period of two weeks or greater in between the application of the isolation coat and the topcoat, wipe the surface down with a soft, lint free damp rag in order to remove any surfactants that could cause a lack of adhesion of the topcoat layer.
POSSIBLE TOPCOATING PRODUCTS
The best clear coats in regard to durability are the 2-part automotive grade urethanes. These products will have the best weather and marring resistance. Unless the artist has the proper spray equipment, respirators, and adequate spraying space, we suggest consulting a local automotive body repair shop and contracting them to apply this kind of product. Creating a test panel made from the exact materials that will be used on the fiberglass sculpture is important so the shop can understand what they are asked to do. They can clear-coat the sample prior to the artwork and both you and the sprayer will have a better understanding of the application requirements.
Outdoor grade 1-part polyurethanes may also be considered for this application; however, they have been known to yellow after application. They may also chip or peel off earlier than the automotive urethane. Other kinds of varnishes such as lacquers, acrylic enamels and epoxies may also be used; however, we cannot offer any suggestions, as we have not completed enough compatibility testing or research for this application.
If a two-part urethane or other acceptable topcoat can not be applied, a secondary option might be GOLDEN's Hard MSA Topcoat (with UVLS). This is a mineral spirit-based acrylic coating that offers UV protection but is non-removable and dries to a rigid, non-flexible finish. It is not considered waterproof and areas where standing water can collect will be prone to blistering and potential delamination from moisture penetration. It is available in Gloss, Satin and Matte finishes, all of which are intermixable. It is recommended to avoid using mixtures of Satin and Matte, or Matte alone for an outdoor application, as these finishes are more likely to retain dirt and dust. Additionally, they are more susceptible to marring if rubbed, and for these sculptures, chances are high that the public will want to touch and even climb on these objects. We suggest consulting the GOLDEN Hard MSA Topcoat literature for information about isolation coats, thinning and other key information.
We hope this information helps artists to achieve long lasting, durable, outdoor fiberglass sculptures, and will encourage, rather than stifle, their creativity. You may have read about some GOLDEN (and other manufacturers) products you are unfamiliar with in the preceding text. If so, contact GOLDEN to obtain more information.
You can access this information at our website (www.goldenpaints.com), in the Product and Application Information section, or call us at (607) 847-6154.
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. While we believe the above information is accurate, WE MAKE NO EXPRESS OR IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, and we shall in no event be liable for any damages (indirect, consequential, or otherwise) that may occur as a result of a product application.