GAC 100 (Product #3910)
GAC 200 (Product #3920)
GAC 400 (Product #3940)
GAC 500 (Product #3950)
GAC 700 (Product #3970)
GAC 800 (Product #3980)
GAC 900 (Product #3990)
GACs can be blended with GOLDEN Acrylic Paints to extend the paint, regulate transparency, create glazes, increase gloss, reduce viscosity or improve adhesion and film integrity. The GAC polymers can also be used for binding pigment solids for various effects and surfaces. Unlike the other GOLDEN Mediums and Gels, GAC Acrylic Polymers have only a minimum amount of thickeners, levelers, defoamers and surfactants to ensure good film formation.
The consistency of the GAC polymers is very fluid, and thinner than other GOLDEN Mediums. GOLDEN Fluid Acrylics are slightly thicker than the GACs, but will be the color line least changed in viscosity with any addition of a GAC polymer.
Each GAC product represents a unique polymer that offers certain specific attributes. Therefore, each GAC will have its own unique benefits and applications. Refer to the individual product description of each GAC (below) to find the proper medium to use for a particular application.
GAC polymers should be gently stirred or rocked back and forth prior to use, but should never be shaken, as this will incorporate significant amounts of foam which will be very difficult to eliminate. Foam can severely affect the transparency of the film causing an apparent foggy or hazy quality. When applying with a brush, use minimal agitation and force, and do not overwork, as this too will result in foaming.
If spray application is desired, blend with GOLDEN Airbrush Medium. Start at 2 parts GAC Medium to 1 part GOLDEN Airbrush Medium. When faster drying is required, replace the Airbrush Medium with GOLDEN High Flow Medium.
The GAC polymers are intended for use as binders, modifiers or additives for acrylic paints. They are not intended for use as a final varnish. Golden Artist Colors manufactures two different varnish systems, Polymer Varnish and Mineral Spirit Acrylic (MSA) Varnish (See the GOLDEN Varnish Information Sheets for more details).
Common supports (e.g. cotton canvas, linen, masonite) contain water-extractable materials that can cause discoloration in transparent glazes. To minimize Support Induced Discoloration (S.I.D.), prime support with 2 coats of GOLDEN GAC 100.
Traditionally, rabbitskin glue (also known as hide glue) was used to reduce the flexibility of canvas before painting. Although the rabbitskin glue does reduce flexibility, it is extremely brittle. It is hygroscopic, which means that it will always be water-soluble. Even when the glue is completely dry, high humidity will re-introduce water into the film, causing it to soften or swell up. Over time, this constant swelling and drying of the film can cause severe paint-film cracking and delamination.
GAC 400 can be used in a similar fashion for stiffening canvas. Apply directly to the front of the raw canvas for maximum stiffness. It is imperative that it be applied directly to the raw canvas. It is ineffective over any other medium, and most likely will flake off and cause delamination of subsequent paint layers. Since GAC 400 is not effective against oil penetration, the use of GAC 100 over GAC 400 is recommended for oil painters
Note: Since GAC 400 is brittle, it is important that it not be rolled tightly, or bent back upon itself. This will cause cracking of the polymer film and may transfer cracks into additional paint layers. This is especially a risk with cured oil paints.
Two coats of GAC 100 before gessoing will substantially reduce linseed oil penetration into the canvas fibers. If stiffness and oil-blocking are desired, apply a coat of GAC 400 to the front, directly into the raw canvas, followed by one coat of GAC 100 onto the front of the canvas. Follow this by the desired number of gesso coats.
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.