What is a Support?
The term "support" refers to any material onto which
paint is applied. Canvas, wood, and paper are common painting
supports, but the types of supports used for artwork are very
extensive. Cave walls and animal skins were among the first supports.
Plaster frescos and wooden panels later became prominent, which
eventually gave way to linen and cotton canvases. Modern supports
such as polyester canvases, AcrylaWeave® and Syntra® panels
will most likely succumb to other advancing technology. The search
for the ideal support is perhaps a never-ending quest, and is
very much influenced by the types of materials available at the
Today's most common supports include acid-free papers, illustration
board, cotton canvas, linen, polyester canvas, masonite, aluminum,
and various wood panels and plywoods.
Choosing a Support
Each artist must choose the support that best suits his or
her needs. The ability to roll a piece of artwork may be required
for transportation or other reasons. Thicker paintings require
a sturdier support; in this case, a timber support may be in order.
The artist must determine what features are most important for
the requirements at hand.
Some times the support is an integral part of the painting itself,
whereby part of it may show through. Using highly polished aluminum
as the support, and priming with clear mediums, will allow thin
transparent colors to appear metallic. Others choose to use coarse
linen so that the weave can be easily seen under the primer and
Most supports need to be prepared to accept a paint system and
to ensure long-term durability. Flexible supports like canvas
may require different preparation steps than rigid supports. A
discussion of these issues follows in the sections listed below.
Abrading a Support to Promote Adhesion
Supports that are non-porous may need to be abraded to create
a surface profile that allows for adhesion of various paints.
This can be accomplished by sanding, scuffing, or sandblasting.
The best way to promote adhesion to glass is by sandblasting,
then applying hard paints to the surface. Some rigid supports
can be simply scuffed with a Scotch-Brite® pad for increased
adhesion. Often, a primer formulated specifically for such a non-porous
surface can be used to insure adequate adhesion.
Cleaning the Support
If the support is an existing building wall or other pre-painted
surface, it will need to be pressure-washed or sandblasted to
remove any defective or loose paint. (See the GOLDEN Information
Sheet "Painting Exterior Murals" for more information
on surface preparation). Failure to do so can have dramatic negative
Before applying paint, 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
To ensure proper adhesion, any support that has been sanded or
otherwise abraded must have the dust removed before priming. This
can be accomplished by using air pressure, vacuuming, or wiping
with a damp cloth, depending on the nature of the support.
Metal surfaces must also be degreased with isopropyl (rubbing)
alcohol or solvent before painting. Other surfaces may also need
to be degreased, to remove soaps or mold release agents, fingerprints,
SIZING THE SUPPORT
What is a Size?
Oil painters must size their canvases to stop the acidic oil
from penetrating into the support, which can cause the fibers
to rot. Traditionally, a hide glue (typically rabbit-skin) was
applied directly to canvas or linen to stiffen the fabric and
protect the support from the acidic oils. Initially this made
hard, brittle paints like tempera and oils less susceptible to
cracking. Ironically, it promoted cracking later on when the artwork
was introduced to varying temperatures and humidity. Rabbit-skin
glue and other known glues of the "Old Masters" era
are hygroscopic, meaning they will always have the ability to
absorb water. When moisture, usually in the form of high humidity,
is re-introduced into this film, the glue swells, changes dimensionally,
and becomes less rigid, causing the paint film to crack and, over
time, flake off. This is most prevalent on cotton and linen canvases
as their inherent flexibility allows the stress to be passed along
to the oil paint film. With rigid supports such as wood panels,
the chance of swelling is much lower, and this glue size is more
To mimic the stiffening effect of rabbit-skin glue, GOLDEN GAC
400 works quite well. It also is effective in stopping the oil
penetration, although GAC 100 has proven to be the best in blocking
oil penetration (see the Stiffening and Oil Blocking sections
Controlling SID in Acrylic Paints
Support Induced Discoloration (SID) is a phenomenon that occurs
in acrylic paints and mediums. Many common artist supports have
impurities that can discolor a translucent acrylic gel layer or
color glaze, and a size must be applied before gessoing to ensure
the products stay clear as the films dry.
As a paint film cures, the water
exits two ways: through the surface of the paint and through the
back of the support, if porous enough. Canvas, linen, wood and
masonite are all porous enough to allow water to absorb into them.
During this drying process, the water is actually in equilibrium
moving back and forth between the acrylic paint and the support.
The water extracts water-soluble impurities such as dirt, sap,
starches, etc., from the support and deposits them into the acrylic
film. The result is a discolored (typically amber) film, with
the degree of discoloration dependent on the amount of contaminants
deposited and the inherent level of impurities in the support.
SID contamination often goes undetected.
In most cases, the paints applied contain a sufficient level of
pigment, thus a strong enough color, to conceal the yellowing.
However, in a transparent glaze and especially in thick translucent
gel layers, SID becomes quite noticeable. SID can transform the
appearance of an Ultramarine Blue glaze into a lower chroma, greenish
color. Gesso alone will not stop SID, and different gels and mediums
have varying degrees of blocking capabilities. The best product
Golden Artist Colors produces to prevent SID is GAC 100. This
thin medium works best when 2 or more coats are applied directly
into the support. Once dry, the canvas can then be primed and
subsequently painted with less potential for discoloration. Pre-primed
canvases can be sealed with GAC 100 as well. Apply one or two
coats onto the surface, and follow with at least one coat of gesso
to regain tooth if needed.
Stiffening Linen and Canvas
GOLDEN GAC 400 functions very well in stiffening fabrics,
especially cotton canvas.
However, it is less effective on linen.
It will not become increasingly brittle
over time, and is not hygroscopic like rabbit-skin glue. Resolubility
of the hide glue can be a problem if a waterborne acrylic gesso,
paint or medium is applied over the glue, causing poor film formation
and possibly delamination from the support.
Maximum stiffness is achieved by stretching the canvas, and applying
a coat of GAC 400 to the front. The result should be a canvas that has
significantly less "bounce" when painting.
Care should be taken if rolling the canvas for shipping or storage as the loss of flexibility will increase the risk of cracking. To minimize this maintain the largest diameter possible and roll with the painted surface pointing outwards.
Blocking Oil Penetration from
GOLDEN Laboratories recently
conducted a study to find out which medium used as a size would
stop oil penetration the best. The results were that two coats
of GAC 100 did the best overall, with GAC 700 and Fluid Matte
Medium also performing well. When using any of these products
to block oil penetration, it was found that a minimum of 2 coats
was required to adequately block the oil, with additional coats
offering additional insurance and protection of the support. A
typical Gesso required 3 or more layers to fully prevent the oil
from passing through to the support. The reason for this is that
the Gesso is designed to be porous and moderately absorbent to
facilitate adhesion of subsequent paint layers.
It is important to allow sufficient
drying time (1 to 3 days) before painting, so that the size can
coalesce into a uniform film for maximum oil blocking.
Stiffening and Blocking Oil
To date, the best system
to both stiffen the canvas and block oil penetration is to first apply
1 coat of GAC 400 to the front of the canvas to develop the stiffening of the fabric, followed by 1 coat of GAC 100 to achieve the oil blocking properties. Once dry, apply 2 coats of Gesso to the front.
PRIMING THE SUPPORT
What is a Primer?
A primer is a foundation layer that improves paint adhesion
onto the support. The traditional oil paint primer was a quick
drying, "lean" paint that sealed and prepared the surface
to accept the subsequent layers of paint. Some of these primers
were made of hide glue and solids (chalks); others were made of
lead white pigment in linseed oil. In the modern sense, a primer
refers to a coating that similarly prepares the surface for the
acceptance of paint. Currently, there are a wide variety of water,
alkyd, oil and urethane-based primers especially designed for
the wider range of paintable surfaces.
Selecting the Appropriate Primer
Primer selection depends equally upon the support and the
paint system to be used. It is imperative to use a primer that
adheres well to the support, as well as ensuring that it offers
adequate adhesion for the subsequent paint layers. Alkyd primers
are well suited for increasing the adhesion of paint to metal.
Automotive primers are often used for spray-applications on metal
surfaces. Many primers are surface specific, like sheet-rock primers,
wood primers and masonry primers.
When searching for an appropriate primer for acrylic paints,
first find one that is intended for the support to be used. Then
be sure that water-based latex paints (of which the acrylic artist
paints are a subgroup) will adhere to the dried primer coating.
Always test out any new materials before applying them to a project
to avoid costly mistakes with incompatible materials.
Acrylic Gesso is an excellent primer for most natural substrates
such as canvas and wood, yet there are great variances between
manufacturer's products. Some gessoes, such as "Student Grade
Gesso," contain low acrylic levels and high solid and water
levels. This type of product has good absorbency but is susceptible
to cracking, especially when flexed, rolled or applied thickly.
GOLDEN White Gesso is formulated with sufficient acrylic levels
to yield excellent flexibility, while also having sufficient pigment
levels to create a favorable level of absorbency and opacity1.
There is enough water to ensure proper shrinkage to tighten a
stretched canvas, yet it is resistant to cracking when flexed.
GOLDEN Sandable Hard Gesso contains solids that facilitate sanding,
but is limited to more rigid supports to lessen the chance of
cracking when flexed.
Acrylic Gesso can be used for acrylic, watercolor, tempera, gouache,
casein, alkyd and oil paints. When using as a primer under rigid
paints (such as oils), the flexibility differences can be counteracted
by using a rigid support (such as wood), or applying a size of
GAC 400 to the flexible support.
Using Mediums as a "Clear Gesso"
Even when an artist intends to have the support show through,
he or she should apply some sort of medium to the surface. This
allows for protection of the support, and may be important for
adhesion of paints to the support as well. The need for adhesion
is especially true when applying thick paints, such as GOLDEN
Heavy Body Acrylics, onto starched canvas or other sizings that
offer some degree of water-resistance to overcome the inherent
hold-out that may occur. Holdout can result in dry paints being
relatively easy to peel away from the unprimed surface.
GOLDEN Fluid Matte Medium, Matte Medium or GAC 100 (for acrylics)
will all work well as clear "gessoes" to allow the look
and texture of the canvas or other support to show through. GOLDEN
Fluid Matte Medium and Matte Medium will result in a clear and
matte surface, while the GAC 100 yields a glossy finish. A minimum
of two coats is recommended.
Thin washes of paint for stain applications will be altered by
the use of any primer. Therefore, the artist can get proper film
permanence by allowing the stained canvas to fully dry, and then
apply the clear "gesso" over it, sealing off the canvas.
This is an important step to ensure the archival2
nature of the fabric. An alternative to such applications would
be to use GOLDEN Absorbent Ground to prepare the support for staining,
as this product offers some unique absorbent qualities (see section
below on this product).
APPLICATION OF A GROUND
What is a Ground?
Historically, a ground is a surface specially prepared for
painting by applying a layer of paint of even tone in preparation
for further painting techniques. Acrylic Gesso can be used as
a ground in the true sense, or a layer of gel, medium or paint
can also be used for this purpose. With the availability of so
many suitable products, a ground can be very specifically tailored
for the requirements of the artist.
GOLDEN High Load Acrylics can be used as "colored grounds,"
as they are very similarly formulated to GOLDEN Gesso. They are
singly pigmented, not tints (pigments blended with Titanium Dioxide),
and have great intensity of color. The "toothy" quality
resembles a gesso, while the high level of pigment provides colorful
Acrylic Ground for Pastels
This GOLDEN product is a relatively translucent ground with
a granular texture similar to fine sand. It provides enough tooth
to simulate a pastel paper's roughness, and can be used under
chalk, crayon, charcoal, graphite and pastel. It can be applied
over other acrylic mediums, gesso or colored backgrounds. Its
toothy nature is effective for dry-brush painting effects. See
the Information Sheet to learn more about GOLDEN Acrylic Ground
GOLDEN Absorbent Ground is a unique product that offers excellent
absorbency, allowing artists to mimic stain or watercolor effects
previously only obtained by watercolor paper. It can also be used
to impart various textured effects by varying the application
tool (coarse brush, squeegee, etc.), and can be applied on any
surface that can be gessoed, allowing for almost unlimited possibilities.
When properly sealed, the work does not need to be displayed behind
glass. For a more detailed explanation of the application of GOLDEN
Absorbent Ground, refer to its Information Sheet.
Additional GOLDEN Products
Most acrylic mediums and gels are stable enough to easily
accept acrylic paints and other types of mediums, such as pastel
and pencils. Always test your applications first before starting.
Pumice Gels (Fine, Coarse, Extra Coarse)
GOLDEN Pumice Gels can be used to create textured surfaces.
They dry to a hard film, yet you can increase their flexibility
by mixing them with other GOLDEN Gels and Mediums. The Fine and
Coarse Pumice Gels can be useful as grounds for pastels.
Clear Granular Gel
Clear Granular Gel has the same textural quality as its pumice
counterparts, but without the gray, opaque grit.
Excellent for building surfaces and creating textures. Dries
to a hard, yet flexible, opaque film.
Light Molding Paste
The density of the wet product is over 50% less than that
of GOLDEN regular Molding Paste. This results in a significantly
lighter film. This dramatic weight reduction will be beneficial
in creating artworks that are large in size, have thick film build-up,
or both. The product dries to an opaque, matte finish, and the
consistency is designed to hold stiff peaks to create a highly
1Opacity - the degree to which a material obscures
a substrate or underlying paint layers.
2Archival - ability to last a long time.
Below are 2 reference charts
to show typical product application to properly prepare the support
to accept paint. These are general guidelines, and certain circumstances
will require additional products and procedures.
Canvas and Linen
Support Minimum Requirements
coats GAC 100 to block SID
Acrylic Washes & Watercolors
Ground for watercolor effect.
& Alkyd Paints
coats GAC 400 to stiffen + GAC 100 to stop oil penetration
Wood Panels, Masonite
and Other Natural Rigid Support Minimum Requirements
or Sandable Hard Gesso (as required)
GAC 100 to block S.I.D.
or Sandable Hard Gesso (as required)
Acrylic Washes & Watercolors
or Sandable Hard Gesso (as required)
& Alkyd Paints
GAC 100 to block oil
or Sandable Hard Gesso (as required)
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