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GAC 400: Fabric Stiffener / Rabbit Skin Glue Alternative.

 

  • Dries to a very hard and stiff film.
  • Most useful for priming fabrics (cotton, linen, silk, etc.) when stiffness is desired.
  • Used as a rabbitskin glue alternative when applied directly to raw canvas or linen.
  • Allows sculpting and shaping of draped fabrics.
  • Can be heat-set if launderability is important. *Note: The heat-setting process will release low levels of formaldehyde; therefore it is imperative that adequate ventilation be provided.

 

PRODUCT DESCRIPTION by www.goldenpaints.com

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, levellers, defoamers and surfactants to ensure good film formation.

 

The consistency of the GAC polymers is very fluid and thinner than other GOLDEN Mediums. Since they do not have thickeners added, these polymers will reduce the thickness of most GOLDEN Acrylic Paints. GOLDEN Fluid Acrylics are slightly thicker than the GACs but will be the colour 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.

 

PRODUCT APPLICATION

 

Mixing:

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.

 

Spraying:

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 Airbrush Transparent Extender.

 

Drying Considerations:

The GAC polymers are milky-white and relatively opaque while in the wet state, but when completely dry they will become transparent/translucent (depending on the nature of the specific GAC).

 

The amount of time that an acrylic takes to dry completely is dependent on several variables, including film thickness, ambient temperature and humidity, airflow patterns and the absorbency of the support. A relatively thin film (approx.1/16 inch) may take from 10 hours to 4 days to lose the milky quality, while a film 1/4 inch thick may take 2 to 10 days or more. It is important to note that film clarity occurs before the film has completely dried, or cured. The thin film mentioned above will take 2 to 3 weeks to achieve complete dryness, while the 1/4 inch thick film will take 2 to 4 months. This is very important to consider when determining how artwork is to be stored. When film transparency is critical, artwork should never be stacked or subjected to high humidity conditions (For a more complete picture about the acrylic drying process, refer to GOLDEN Information Sheet: Technical Notes on Drying).

 

Varnishing:

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).

ADDITIONAL INFORMATION

 

Support Induced Discoloration:

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.

Replacing Rabbit skin Glue:

 

Traditionally, rabbitskin glue (also known as hiding 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. Although the GAC 400 will not quite achieve the stiffness of the rabbitskin glue, it does not remain water-soluble. Apply one or two coats directly into the raw canvas, coating both front and back 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 it is an acrylic polymer, it is not hygroscopic. However, neither rabbitskin glue nor GAC 400 is completely effective against oil penetration, and 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.

 

Linseed Oil Blocker:

Two coats of GAC 100 before gessoing will substantially reduce linseed oil penetration into the canvas fibres. If stiffness and oil-blocking are desired, apply a coat of GAC 400 to both the front and back, 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.

 

GAC 400: Fabric Stiffener / Rabbit skin Glue Alternative.

 

  • Dries to a very hard and stiff film.
  • Most useful for priming fabrics (cotton, linen, silk, etc.) when stiffness is desired.
  • Used as a rabbitskin glue alternative when applied directly to raw canvas or linen.
  • Allows sculpting and shaping of draped fabrics.

GAC 400 - Golden Mediums

C$19.95Price
  • Please contact us to purchase by calling 403-258-3500 or by simply emailing us at info@swintonsart.com. We are not yet an E-commerce business. All purchases will be in-store or shipped by call or email.

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