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. 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 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
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 Airbrush Transparent Extender.
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, air flow 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
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).
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 Rabbitskin Glue:
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.
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 fibers. 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 POLYMER INDIVIDUAL
Use the below descriptions
to decide which attributes are best-suited for a particular application:
GAC 100: Universal Acrylic
Polymer / S.I.D. Blocker / Most Flexible GAC Polymer.
- This polymer is one of the most
universal used in paint manufacturing. Artists who had used
"Rhoplex" (a registered trade name) will find that this GAC
most closely reflects the properties to which they were accustomed.
- The GAC 100 is a useful polymer
for protecting against Support Induced Discoloration (S.I.D.).
- The most flexible with a moderate
level of tack and gloss.
- Useful for diluting and extending
colors, especially when film flexibility and integrity are important
- Wets pigment surfaces well.
The most ideal for artists formulating their own paints.
GAC 200: Increases Film
Hardness of Acrylic Paints / Increased Non-porous Surface Adhesion.
- The hardest and least flexible
of any Golden Acrylic product. Caution is advised when using
this product alone.
- Used in its pure form, it is
limited to applications on rigid supports, as its lack of flexibility
may lead to cracking when flexed. Under certain conditions,
the medium alone may crack upon drying.
- Ideal as an additive to acrylic
paints to increase film hardness and reduce dry film tack.
- Improves adhesion to non-porous surfaces; however some surfaces, such as glass and glazed tile, will not allow for a permanent bond
- Dries with high gloss and excellent
- Promotes cleaner edges of hard-edge
techniques. The harder paint film has less "pull" as the masking
tape is removed.
GAC 400: Fabric Stiffener
/ Rabbitskin Glue Alternative.
- Dries to a very hard and stiff
- 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 500: Self Leveling Applications
/ Hard Yet Flexible / Best Isolation Coat Medium for Spray-Application.
- Unique balance of film hardness
- Mix 2 parts GAC 500 to 1 part
Airbrush Transparent Extender to produce a good spraying,
fast-drying isolation coat.
- Beneficial as an additive for
acrylic paints for increasing mar resistance and decreasing
dry film tack, without disturbing the balance between hardness
- Useful when working on flexible
or rigid supports.
- Offers a self leveling working
- Dries to high gloss film with
- Useful to hard-edge painters
to seal masking tape for cleaner edges. Apply over masking tape.
Let dry before applying additional paint layer.
GAC 700: Increases Film
- Dries to a clear, high gloss film, with moderate hardness and exceptional transparency.
- Offers reduced shrinkage upon drying.
- *Note: This emulsion has a tendency to generate foam during application. Exercise care while brushing.
GAC 800: Reduced Crazing
of Dried Films / Best for Direct Pouring.
- Most useful as an additive for
acrylic paints when pours/puddles are desired to dry with the
same film thickness and smoothness as when wet. Most acrylics
will craze, which is the formation of valleys that run through
a pour/puddle nullifying the uniformity of the film. Such crazing
is the result of shrinkage forces exerted during the drying
process. GAC 800 stands alone in its resistance to such film
- Dries with good gloss and film
flexibility, but with a slight "hazy" quality.
- Useful as a modifier when adhesion
to chalky surfaces is desired.
GAC 900: Increases Launderability
of Acrylic Paint.
- Designed to be used as a modifier
for acrylic paints for painting on clothing. See the
GOLDEN Acrylics on Fabric Application Information Sheet
for more extensive information.
- Offers a soft, pliable feel
and when properly heat-set, provides excellent laundering stability.
- Blend with GOLDEN Heavy Body,
Matte or Fluid Acrylics for brush or screen application.
- Mix with GOLDEN Airbrush
Colors for "Tie-Dye" effects.
- Note: The heat-setting process
will release low levels of formaldehyde; therefore it is imperative
that adequate ventilation be provided.
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.
© Golden Artist Colors, Inc.