ACRYLIC POLYMER
Acrylic polymer paints were initially developed as industrial paints that were first
used by artists after WW2. Acrylic polymer paints are composed of pigment
suspended in acrylic resin (Rhoplex). When wet, polymer paints are soluble in
water, but dry to an insoluble hard plastic. Acrylic polymer paints (commonly
called acrylics) are extremely versatile and can be applied with a wide range of
textural effects. To create bled or poured effects, polymers can be directly
applied to raw, unprimed canvas. Oil paints cannot be used in this way because
acids naturally present in the oil will eventually cause canvas to deteriorate.
Because acrylics are fast drying, thickly painted works can be completed quickly.
If necessary, an acrylic retarder can be mixed with acrylic paints to help slow
their drying. Acrylics are well suited for building transparencies and/or flat color,
rather than for painting that requires delicate control and blending. Acrylics will
peel from glass or other non-porous surfaces but bind well to cloth, wood, and
unglazed ceramic.
Polymer medium - is the binder of acrylic paints that can be mixed with polymer
colors to create smoother consistencies and glazes. A polymer medium (matte
or gloss) has a milky color when wet, but dries completely transparent if used
properly. Gloss medium can be used as a final varnish over acrylic painting.
Matte medium works the same way, but has a duller finish. Polymer medium may
dry cloudy when brushed continuously while drying or when diluted with too
much water (not to exceed 25% water to medium).
Iridescent medium is available for "metallic" color mixtures. An iridescent color
can be made by mixing a transparent acrylic color with this medium.
Polymer mediums can also be used as adhesives and work well when
incorporated in mixed-media and other techniques. Polymer mediums are ideal
for use in collage, or attaching tissue paper to the surfaces of canvas or board.
Oil paint, oil glazes, and oil sticks can be applied over any acrylic surface. Chalk
pastels (pigment plus clay) can also be used in combination with acrylic or oil
paints.
Acrylic Polymer Gesso - is used as a primer (or ground) for both acrylic and oil.
Acrylic gesso is usually opaque white, however black gesso is available for
opaque black grounds. Color gesso can also be purchased for artists interested
in using color grounds.
Taping - Sharp edges can be made in acrylics without the paint bleeding or
crawling under masking tape. Artists seal the masking tape edge or edges with
polymer medium, allowing it to dry, then painting in the masked-off areas.
Textural effects with acrylic mediums
Along with gloss, matte, and gel medium, acrylic polymer gesso can be mixed
with aggregate materials such as sand, marble dust, or cement to produce
textural or sculptural effects.
Gel medium - Similar to polymer medium, polymer gel can be mixed with varying
amounts of acrylic colors to create opaque or transparent impasto effects. Used
by itself, gel medium dries transparent. It is well-suited for mixed media
techniques and can be used as an adhesive or applied on top of collage,
modeling paste, cloth, wood, unglazed ceramic, sanded metal, or any acrylic
surface. Gel medium is now available in matte, gloss and opaque finishes.
Modeling Paste - Modeling paste is a blend of acrylic polymer and marble dust.
Textural effects can be created with modeling paste directly on gessoed
surfaces. However, modeling paste may crack on flexible surfaces (such as
canvas) unless gel medium is added. Modeling paste is opaque and is primarily
used to create textured surfaces before paints are applied. Generally speaking,
acrylic paint is not mixed with modeling paste.
BRUSHES
Brushes come in a wide variety of shapes and sizes, and are designed to do
different things with paint. White bristle or "hog's hair" are the most popular stiff
brushes used by oil and acrylic painters. This natural bristle comes from the
coarse hair found on the backs of pigs. Because these brushes are stiff and
"springy", thick paint can be pushed and blended on the surface. Sable brushes
are the best of the soft bristle brushes. The hairs of this brush are reddish in color
and taper to a natural point. These brushes are ideal for delicate and controlled
paint manipulation, such as glazing, and like white bristle, are "springy" for easy
control. Sable brushes are very expensive and should be treated with care.
There are synthetic and sable blends called "sabeline" available today which are
much cheaper and do a good job as a soft bristle brush. Synthetic white bristle
brushes share many of the characteristics of both sable and natural white bristle.
Unfortunately, these brushes do not work well with oil painting because oil paint
tends to bead-up in the synthetic hairs. Like the sabeline brush, there are natural
white and synthetic bristle blends available to the artist.
Paint brush styles
Styles of brushes also vary depending on their use. The round is good for
making thin drawing lines or for painting details. The brushes used most
frequently in oil and acrylic painting are flats and brights. Both brushes have a
straight or chiseled end, though brights tend to be shorter in length. White bristle
flats or brights hold a lot of paint and are used to cover large areas quickly. The
bright is the best blending brush available. Filberts are similar to flats and
brights, except that they have rounded corners which create a different edge on
the paint stroke. All brushes can be turned in a variety of directions to create
different types of brushstrokes.
Using a paint rag
A lint free rag can be used to make marks or pull the paint from the surface. A
rag also erases large or small areas of paint. A brush is used in combination with
a rag to control the amount of paint and liquid in the brush. A rag is an essential
painting tool. The best rags are made from cut up T-shirts, because they are
absorbent, soft, and lint free.
Keeping brushes clean
For oils, keep brushes in a tin can or glass jar that contains odorless
spirits. To keep brushes from resting in paint sediment that has
settled to the bottom of the can, place a piece of wire window screen
about 2 or 3 inches from the bottom of the can. (A crumpled wad of
window screen that fits snugly at the bottom of the can works well.
Make a smooth "face" for the brushes to rest against). The rough screen helps to
clean brushes and keeps them away from the sediment.
Brushes used with acrylic paints or mediums should be kept in plastic or glass
jars containing cold water. Tin cans rust and can alter the color of paints.
Brushes must be kept in water when not in use and cleaned with cold soap and
water. Any acrylic residue left in brushes will dry to a hard, insoluble plastic.
Palette knives are used to mix paint on the palette. The best palette knife is
bent, which helps to keep knuckles from getting in the paint. Painting knives are
used as actual painting tools to create textural effects and are especially useful
for thick applications of paint (impasto).
GETTING STARTED
Step 1 -- Sketching directly onto a ground with diluted paint is the most
immediate and will give you truer colors. Thin paint with a solvent (turpentine or
OMS), or an oil medium that contains mostly solvent and very little oil (or in
acrylics, thin with water). The color used for the sketch can vary -- some teachers
recommend using neutral browns, such as burnt umber or burnt sienna. Others
suggest more vibrant colors ranging from blues to greens. Still others
recommend using ivory black. Regardless of the sketching colors you choose, it
is important to use a color that creates a wide range of values. Avoid slow-drying
colors -- in oil, the "browns" dry very quickly and can be covered usually in a day
or two. Standing away from the painting during the sketching process will allow
you to "map" out the composition quickly. Shade in areas and use a paint rag
(with a solvent, if necessary) to remove or erase paint. At this point, it isn't
necessary to have a meticulous or perfect drawing; in fact, this wastes time,
because you will be eventually covering the sketch with additional layers of paint.
If you must, sketch with pencil, chalk, or pastel. However, a careful, tightly
rendered drawing will be lost when you begin to layer your paints. Shade in
areas, but keep the drawing loose. Don't use charcoal or other dark drawing
materials. If the drawing materials used are too dark, they will mix with your paint
and cause it to become dark and muddy. If you choose to draw in pencil or
another "dry" medium, liquefy the material by adding a thin oil or thin acrylic
painting medium (depending on the type of paint that you use). Binders in the
medium help the pigment stick to the surface.
Step 2 (Blocking-in color) -- This may be the most important step in painting.
The most efficient way to achieve a good composition and unity in a painting is to
initially develop large color areas. For oils, block in areas with paint that has been
thinned with an oil medium that contains mostly solvent. In acrylics, use paint that
has been thinned with water or a polymer medium. Use only necessary colors.
Block in the entire surface, including the "background" and negative areas.
This should be done very quickly and with a large brush. You should be standing
during this process so you can get back and see the "whole" surface area, rather
than getting caught up with details. Consider color harmonies or color schemes
in the work.
Step 3 -- After the overall color plan is completed, the next layers of paint, which
might include blending or dabbing can be started. Working from thin to thick is a
sound rule. Some painters do a lot of blending. This is achieved by applying
patches or dabs of paint over an area before they begin blending in the paint.
Other painters try to build up fresh, unblended dabs or strokes on the canvas.
Impasto paint applications may also be used at this stage of the painting.
In oil paint, apply more oily layers of paint over less oily areas (fat over lean).
Otherwise, your painting may crack. This problem does not occur with acrylics,
because they can more easily expand and contract. After the initial sketching
and blocking in layers, use a medium that has been mixed in advance for
the remaining painting. This can alleviated many problems with
consistency. Avoid mixing pure oil or pure solvent with your paint in these
subsequent layers.
Step 4 -- Final stages
Because oily layers should be applied over leaner layers of oil paint, transparent
glazes made with an oil medium generally should be applied during the final
stages of an oil painting. Glazes can create transparencies in specific color areas
to unify the painting. They may be applied in one or more layers over transparent
or opaque paint. Using glazes in this way differs from traditional glaze painting
discussed below. Acrylic glazes can be applied on acrylic painting at any stage of
the painting.
Notes on starting a painting
Because oil paint lends itself to blending, it an excellent paint to use if you are
working in a realistic style. Oil will often dry in one or two days, however, so it
makes sense to finish particular areas in one sitting. If the paint is allowed to dry
on an unfinished area, wet paint will have to be reapplied in order to complete the
work. An oil painting medium will increase the creaminess and fluidity of the paint
and can slow the drying time, if desired.
Using reflective colors at this stage will give a unified quality to the work. This is
achieved by "unloading" varying amounts of one color to another color area.
Reflective color use is only one option, however. Some artists prefer working in
pure areas of color. This often lends vibrancy to the work because of contrasts in
the individual color areas. Sometimes work done in this way may have a
fragmented appearance in color, not unlike what one might associate with
"coloring". Areas may seem unrelated or filled-in. Limiting the palette, repeating
the colors in the work, or using limited amounts of reflective color will help.
Creating powerful value contrasts by darkening and lightening colors will also
give the painting "structure" and therefore, give the work more coherence.
The danger of adding black or white to color is that the relative purity of the color
diminishes. One should also think in terms of contrasts in color, such as
complementary colors and other color schemes, to increase the vibrancy of a
work.
Perhaps one of the most effective ways of developing space in painting is
through the use of cool and warm colors. Cool colors recede in space, i.e., blues,
violets, blue green and blue-violet, while warm colors appear to push forward in
space, i.e., yellows, oranges, reds, red-oranges and yellow-oranges. The
impressionist painters used cool and warm colors to create ranges of depth
rather than relying on tints and shades to create spatial contrasts, as was often
done by the traditional academic painters. The impressionists often used white to
lighten colors, however.
Drying time is effected by the amount of oil present in the paint or painting
medium. Painting mediums made with a higher proportion of oil will cause the
paint to dry more slowly (an often desirable effect). Some colors, such as
titanium white or ivory black, contain more oil and therefore dry more slowly.
Some manufacturers mix more oil into their paints than others. The thickness of
the paint also effects drying time. Oil paints dry more quickly in warm conditions,
as well. In the summer, oil painters will sometimes warm their paintings in direct
sunlight to accelerate the drying time. Because of all these factors, it is often very
difficult to predict the speed at which an oil painting will dry.
Drying can be somewhat controlled by the type of oil used in the medium -- for
example, sun-thickened oil dries rapidly and is useful in glazing or
transparencies, because layers can be covered very quickly (sometimes in 24
hours). Stand oil is slow drying, so areas stay "workable" for much longer. Stand
and sun-thickened oil are ideal in painting mediums and can be mixed together
for even greater control of drying. A tiny quantity of cobalt dryer can be added to
a medium made with stand oil to increase its drying time. Mediums made with
refined linseed or safflower oil are runny and harder to control than those made
with stand or sun-thickened oil. Refined linseed oil can be mixed with either of
the thicker oils if necessary. Commercially produced mediums made with alkyd
resins make oil paints dry more quickly than mediums made with traditional
drying oils.
Acrylics dry more quickly than oil, so learning how to layer wet paint over dried
areas is key to understanding this medium. To increase the fluidity of the paint,
and add to the transparency, add water (no more than 25% water) or mix in any
proportion of matte or gloss medium. Matte medium has a duller finish than
gloss. The type and style of painting will ultimately determine which medium to
choose. On very dark paintings, gloss medium will cause the surface to be highly
reflective. This can sometimes make the painting difficult to view in some lighting
situations.
It is also important to work from thin to thick in acrylics, especially if you want to
use impasto techniques. Thick acrylic cannot be removed or changed after it has
dried.
Oil glaze paintings -- A traditional oil glaze painting requires a different
approach than the opaque painting described above. Artists first complete a thin
tonal underpainting using a thin glaze medium with black or brown oil paint. This
tonal painting is traditionally called a grisaille from the French "gris" (meaning
gray in English). Layers of transparent color (see Pigments for a list of
transparent oil colors) are mixed with a painting glaze medium and applied over
this fairly accurate and exact underpainting -- allowing the "drawing" to show
through the glazes. Many glazes can be layered on top of one another. The
intense luminosity of an oil glaze painting is created by light reflecting through the
transparent layers of thin glazes. When done correctly, oil glaze paintings are
incredibly luminous.
Acrylic glaze paintings -- An acrylic glaze painting is created with a similar
step-by-step process used in an oil glaze painting. Acrylic glazes can be made
with either gloss or matte medium. Small amounts of transparent acrylic color
can be added to the acrylic medium. Use limited amounts of water, as it will
reduce the transparency and perhaps even make the color cloudy. One
disadvantage to using acrylics is that wet polymer mediums lighten the
appearance of colors, and the resulting dry glaze can differ dramatically from the
wet mixture. More precise glaze colors can be tested, then measured and
premixed and stored in airtight containers. An advantage is the quick drying time,
so subsequent layers can be painted in a manner of minutes rather than
overnight.
Combining oil and acrylic -- Painters can begin a painting in acrylic and
complete it in oil glazes. The oil glazes bring a rich, luminous quality to the acrylic
underpainting.
Cleanup
Use odorless thinners and soap and cool water to clean oil paint from brushes,
etc. Hand cleaners such as Goop work well for cleaning oil paint brushes
because of their grease-cutting properties. Mineral oil will also clean oil paint
from brushes. Murphy's Oil Soap works well for cleaning brushes and removing
oil paint from clothing, although Murphy's Oil soap will swell the bristles of paint
brushes if they are soaked. DO NOT DISCARD OIL OR OIL SOLVENTS IN THE
SINK. DOING SO WILL CLOG THE SINK.
Use plain soap and cool waterGROUNDS
A ground is used with both acrylic and oil paints to create a nonabsorbent
surface on which to apply paints. The ground ensures the proper binding of paint
to the surface, helps to separate mildly acidic oils from the support, and allows
the painting to retain its brilliance of color. Grounds are usually white, enabling
light to reflect from the surface. Before the use of acrylic gesso, artists sized rigid
and flexible supports before applying the ground (see preparing traditional
supports). Acrylic gesso functions as both a size and a ground, making this a
one-step preparation rather than two. According to the excellent painting text,
Painting as a Language by Jean Robertson and Craig McDaniel, priming is the
accurate description of the entire process of preparing a support -- either the
traditional two-step or the acrylic one-step procedure. Nonetheless, acrylic gesso
is often referred to interchangeably as both a ground and primer, presumably
because it is a one-step, simple preparation. What is important to remember is
that there are several ways of preparing supports and that artists should use
surfaces on which:
1. paint can properly and permanently bind
2. pigment and binder will not be absorbed
CREATING A GROUND FOR CANVAS OR BOARD
Most painters use gesso as a ground for their paintings. An Italian word, "gesso"
means gypsum and was originally used to refer to the plaster surfaces on which
fresco painters executed their work. Eventually this term was used to describe
other painting grounds, such as gesso sotile, and most recently, acrylic gesso.
The most popular ground used today is acrylic polymer gesso because of its
versatility, easy use, rapid drying, and flexibility. Acrylic gesso is considered
adequate as a ground for oil paints, although this is somewhat controversial.
Some oil painters and technical experts argue that the flexible acrylic surface will
cause oil paint (which dries brittle and becomes even more so over time) to
crack. (This would also apply to any acrylic surface, including acrylic paints, gels,
mediums, and modeling paste).
In addition, acrylic gesso is somewhat absorbent, causing some colors in oil paint
to dry matte or dull. Painters can add small amounts of stand oil or oil medium to
a rag and rub the dull area to restore is color brilliance, a process known as
"oiling out".
Using traditional grounds can also prevent oil paints from drying matte or dull.
Many oil painters prefer traditional surfaces, because they are almost completely
nonabsorbent, stable, and permanent. Alkyd-based gesso, when used with rabbit
skin glue, will also create an excellent, nonabsorbent and stable ground for oil on
canvas.
Acrylic gesso has been used for fifty years and many oil painters, nonetheless,
prefer this ground over others because of its convenience. Manufacturers label
this gesso as suitable for acrylic, tempera, and oil.
Acrylic polymer gesso works as both a size (see below) and a ground, because it
fills in holes and creates a barrier between the paint and the canvas. Because
acrylics do not effect the integrity of the raw canvas or board, some acrylic
painters even eliminate the use of an acrylic gesso ground in order to attain bled
effects. However, most acrylic paintings are done on acrylic gesso grounds.
Acrylic gesso is soluble in water, so cleanup is very simple using soap and water.
Polymer gesso, paints, and media must not be allowed to dry in brushes, as they
will harden to insoluble plastic.
Ideally, acrylic gesso should be applied in thin layers, the first being the thinnest.
A dilution of 2 parts gesso to 1 part water brushed in a direction that follows the
weave is good for the first coat. After the first coat is dry, another thicker coat (3
parts gesso to 1 part water) brushed perpendicular to the first should follow. Each
dry coat should be lightly sanded. Several more coats should be applied in the
same manner. Four or five thin, sanded layers of gesso make a far superior
surface than one or two thick coats.
Rigid supports, such as masonite and wood panels should be prepared in the
same way, though coatings should be applied to both sides of masonite panels, if
the panels are not glued to a frame. This will prevent warping.
Acrylic gesso may be mixed with various acrylic media, such as matte or gloss
medium. This creates a less absorbent surface which lends vibrancy to color and
prevents brushes from "dragging" across the surface.
To create an extra smooth surface on a stretched canvas using an acrylic gesso
ground, a squeegee can be used to apply the gesso to the surface. Pour an
adequate amount of gesso onto the middle of a canvas that is lying flat and face
up on a protected floor or table. A squeegee can be made from a piece of mat
board or other rigid material. The gesso is squeegeed evenly over the entire
surface making sure that ridges and drips are smoothed. Excess gesso can be
gathered on a corner or edge and pushed into a gesso container. Put the canvas
upright for drying to prevent sagging. Sand and reapply subsequent coats also
with a squeegee.
Colored grounds -- tonal or imprimatura
Artists often prefer working on a colored or neutral colored ground. Forms can be
developed easily on these surfaces, and color can appear more vibrant.
Tonal grounds are flat and opaque . Color is mixed with white paint to create the
opacity.
Transparent color applied to a ground is called an imprimatura. This flat,
transparent colored layer allows light to pass through to the original surface
which reflects back through subsequent layers of translucent or transparent
paint. Thin washes of acrylic can be applied to create a transparent color on an
acrylic gesso ground. Replacing the water with at least 75% matte medium will
improve the transparency of the imprimatura.
Oil paint thinned with odorless mineral spirits (oms) or an alkyd medium can be
painted on acrylic gesso surfaces as well, provided the remainder of the painting
be done in oil. On oil grounds, such as alkyd gesso, lead white, or gesso sotile,
oil paint washes thinned with either an oms or an alkyd medium can be painted
on the surface and dried before continued painting (see below). Alkyd paints
work well as colored grounds for oil paints because they dry quickly. Oil-based
grounds, including materials containing alkyd resins, are not suitable for acrylic or
water-based paints.
Neutral grounds were often used by painters, such as Rembrandt or Frans Hals,
who were interested in creating dramatic lighting effects or chiaroscuro which is
easier to achieve on neutral colored surfaces. Carravagio is perhaps the artist
best known for using this dramatic effect.
Textured grounds for both oil and acrylic - Painters can work on textured
surfaces made from acrylic mediums. These textured grounds are considered
suitable for oil, as well as acrylic (see Textural effects with acrylic mediums).
Preparing traditional supports for oil painting
Sizing - Before the use of acrylics, painters sized both flexible and rigid supports.
(Sizing is not necessary when using polymer gesso as a ground for either oil or
acrylic painting). Sizing protects the raw canvas or board from acidic oil-based
grounds or paint. Sizes also fill in holes in the canvas weave and grain of the
wood. When glue size is applied to stretched canvas, it becomes very tight.
Most sizes are made from animal hide glue, the most common of which is rabbit
skin glue. Rabbit skin glue crystals are available from art supply stores.
Crystallized glue (the size of crushed gravel) must be soaked overnight before
preparing the size. Granulated rabbit skin glue crystals don't have to be soaked
and can be prepared immediately.
The crystals are dissolved and melted into heated water (the glue should never
be boiled). The hot, liquid glue is brushed (2"- 3" wide) onto the canvas, wood, or
masonite. The glue should be brushed into the weave of the canvas. Brush a thin
layer, starting from the center and working outward. As the glue cools it will begin
to congeal. You may reheat the glue size in a saucepan to apply subsequent
layers (usually two coats). Masonite and solid wood panels should be sanded
prior to sizing to assure proper binding of the glue.
Oil-based grounds for oil painting - Some oil painters prefer traditional
methods for preparing canvas. Though time consuming, these methods create
excellent nonabsorbent surfaces for oil painting that allow oil paints to properly
(and permanently) bind to the ground:

For oil on canvas - Begin by sizing the canvas with two coats of rabbit
skin glue. After the glue size is dry, apply with a brush or painting knife a
smooth layer of oil priming white or flake white. The priming white should
be thinned with turpentine to the consistency of sour cream. Allow the
surface to dry for several days or until the priming white is dry to the touch.
A second coat of the same consistency of priming white may be applied
and then dried for several weeks. Placing the canvas in the sun helps to
speed up the drying time. Priming white and flake white contain lead
pigment and are poisonous, so care in their use is extremely important.

Grounds for rigid supports - In addition to acrylic gesso grounds,
traditional gesso grounds, known as gesso sotile can be applied to presized masonite panels. Gesso sotile raises the grain on birch plywood
panels, so this method should be reserved for use with masonite.
Basically, gesso sotile is a mixture of dry white pigment and warm, liquid
rabbit skin glue at a ratio of about 1 or 2 parts pigment to 1 part glue.
There are several white pigments that can be used in this mixture, a
typical one being a 50/50 blend of titanium or zinc white pigment and
French chalk or whiting (calcium or magnesium carbonate). The pigment
is mixed directly into the hot, melted glue. The warm gesso is applied to
the sized masonite in one direction. After the ground is dry, it should be
sanded lightly to remove roughness. Several coats of warm gesso should
be applied (with sanding in-between) in directions perpendicular to each
other.
Alkyd Gesso - Gesso made from alkyd resins and white pigment can be used
for an oil painting ground on either canvas or rigid supports. Canvas supports
should be sized with rabbit skin glue before applying the alkyd gesso. This gesso
can, however, be applied directly to rigid surfaces. Each coat of alkyd gesso
(lightly sanded) will dry overnight. An oil painting can be started after two coats,
so relatively speaking, preparing a surface with alkyd gesso is much faster than
with traditional glue size and lead white techniques. Alkyd gesso is nonabsorbent
and will allow oil paints to dry glossier and more vibrant. to clean acrylics.
Dishwashing detergent or liquid hand soap work fine. Water can be poured down
the sink, but thick chunks of acrylic paint should be thrown in the garbage.
Place the brush in the palm of your hand and swish the brush to remove the
paint. Run water through the brush and repeat the process until the water runs
clean. Reshape the brush with your fingers and store in a jar or can handle-side
down.
OIL PAINT
Oil paint became widely used in the 15th and 16th centuries, although oil was
mixed with egg tempera in medieval painting. The early oil painter was given the
advantage of blending and mixing paints directly on the support rather than
carefully layering them, as was the case with egg tempera. Because oil paint
dries slowly, surfaces can be worked for hours or sometimes days. The key is to
keep the paint fresh and alive by not overworking and creating muddy color.
Artists can easily change areas by wiping with a turpentine rag or scraping with a
painting knife. Oil paint must be used on top of a prepared surface (see
Grounds), in order to create a barrier between the acidic oil paint and the
support.
The traditional solvent for oil paint is turpentine. Turpentine is used in traditional
oil painting mediums, especially those that contain damar varnish. Unfortunately,
turpentine produces noxious fumes. Mineral spirits or paint thinners also produce
dangerous fumes and should only be used in well-ventilated areas. Odorless
mineral spirits (OMS) is now available, which dramatically cuts down on noxious
fumes (see solvents). Popular brands available locally are Turpenoid and
Houston Art (Mona Lisa).
Oil paints cannot be mixed with water or water based paints, including
acrylics. Some artists, however, layer oil paints on top of dry acrylic paint
or gesso, which can create interesting effects. Acrylics cannot, however,
be used on top of oil paints because they will not properly bind to the oil
surface.
Drying Oils - Vegetable oils like cold-pressed safflower oil or refined linseed oil
are used in artist's oil paints because they are non-yellowing, quick drying, and
durable. Boiled or raw linseed oil available in hardware stores is unsuitable for
artist's oils, because they are heat-treated and will yellow the paint in a relatively
short period of time.
Artist's Refined (cold-pressed) linseed oil
This is the most widely used oil in artists' paints. It is light amber in color and slowdrying.
Poppy Oil
A slow drying oil, this medium is used in alla prima techniques. Poppy oil is not as
durable as linseed oil and can crack more easily, however.
Cold Pressed Safflower Oil
Similar to linseed oil, safflower oil is very clear and non-yellowing. The best sources for
cold or expellor pressed safflower oil are health food stores where it can be purchased
much more cheaply than at art supply stores. Avoid mechanically pressed (heat
treated) safflower oil found in conventional groceries. These oils will yellow.
Stand Oil
Made from linseed oil, stand oil is thicker, which improves paint flow. Stand oil is
thickened by heating it under controlled conditions that make the oil non yellowing.
This oil gives a glossy-like finish which does not show brush strokes. Stand oil is
excellent when used in glazing mediums. It dries slowly.
Sun-thickened Oil
Sun-thickened oil is prepared by naturally thickening linseed oil in sunlight. Sunthickened oil is similar in consistency and workability to stand oil, however, sunthickened is fast-drying -- in fact mediums mixed with this oil can dry within a day.
Stand and sun-thickened oils should be mixed as a painting medium before being used
with oil paint.
When using oil paint, the first layers should contain less drying oil than the
subsequent layers. This is the principle of fat over lean. A painting should be
planned so that the underpainting is lean or low in oil content. These initial layers
should be thinned with a medium composed of large amounts of solvent with
smaller amounts of oil. Oil expands and contracts as it dries (oxidizes). If lean
(low oil) paint is brushed over fat or oilier paint, the fat area's flexibility
underneath may cause the lean (and more brittle) layer on top to crack.
Underlayers which are not completely dry also release gases that will crack a
more brittle, less oily overlayer.
OIL PAINTING MEDIUMS
Homemade oil mediums
Oil paints may be thinned with a mixture of oil and turpentine. However, it is best
to premix an oil painting medium beforehand to insure consistency. A
traditional medium that can be used for both thinning paints and glazing can be
mixed with 1 part oil, 1 part damar varnish, and 1 part turpentine. If you are using
odorless mineral spirits, you should eliminate the damar varnish, because it will
not dissolve properly (1 or 2 parts oil to 1 part OMS). Replacing the linseed oil
with sun-thickened will make a richer, faster drying medium. Using stand oil
rather than linseed oil will also create a thicker and richer medium, although it will
dry slower than a medium made with sun-thickened oil. Stand oil also gives the
paint a glossier finish. (If you use the stand or sun-thickened oils, a thinner
medium can also be made using 1 part of these thicker oils to 2 parts OMS.)
Ralph Mayer's glazing medium - Ralph Mayer's, The Artist's Handbook of
Materials and Techniques, includes several glazing recipes used by oil
painters. A standard recommended glazing medium for an oil glaze painting is
composed of 1 ounce stand oil, 1 ounce damar varnish, 5 ounces turpentine, and
15 drops of cobalt dryer. The cobalt dryer is added to accelerate the drying time
of the slow drying stand oil, but if too much is added, the medium will coagulate.
Ideally, a glaze should dry rapidly so artists can proceed with layering
subsequent transparencies. The best glazes will dry overnight.
Impasto wax and oil medium -- An impasto wax medium for oil paint can be
made by gently and slowly melting 1 part bleached beeswax into 2 parts linseed,
sun-thickened, or stand oil. Pour the oil in a coffee can and place this into a pot
of hot water (basically, a double-boiler). When the oil is hot enough to melt the
wax, place small pieces of beeswax into the oil until all the wax is melted. Stir
thoroughly and allow to cool. If the mixture is too hard or too oily, reheat and add
either more wax or oils as necessary. A drop or two of cobalt dryer can be added
to help the medium dry more quickly. The final consistency should be similar to
lard. Store oil painting mediums in glass jars with lids.
Making homemade sun-thickened oil - The process of thickening oil is
described in The Materials and Techniques of Painting, by Jonathan
Stephenson. In the summer (or the tropics), pour about 1/2" - 1" thick linseed oil
onto a flat, glass dish. The flat dish creates a large surface area for exposure to
the sun and the air. Place the dish outside (on a ledge or roof) in an area that will
be exposed to the maximum amount of sunlight. Thickening oil happens fastest
in warm, sunny climates. Cover the dish with a slightly opened glass lid to allow
for air flow. Stir the oil daily. After about a week or two, stir occasionally to
prevent a skin from forming over the surface layer of the oil. Continue the
process until the oil has thickened to a syrupy consistency. Impurities will settle
to the bottom, so the oil on top can be poured off. Store in a glass jar with a lid.
Commercial oil painting mediums
Many art supply companies produce a variety of painting mediums for use with
oil. In addition to traditional oil mediums (such as copal painting medium), many
oil painting mediums are made with fast-drying alkyd resins which are soluble in
odorless mineral spirits. Popular brands are Gamblin Paint Companies' Galkyd
Medium #1 and Galkyd Lite#2, Daniel Smith's Painting Medium for Oils and
Acrylics, Utrecht's Alkyd Glazing Medium, as well as Winsor Newton's Liquin.
Alkyd based translucent impasto gels are also available, such as Gamblin's
Galkyd gel, Utrecht's Flex Gel, and Winsor Newton's Oleopasto. Gamblin also
produces a Cold Wax Medium for opaque impasto applications.
Alkyd mediums are far less toxic than traditional oil mediums. They dry glossy
and transparent. To extend the "open" time of fast drying alkyd mediums, small
amounts of drying oil may be added. To prevent wrinkling, not more than 10% is
recommended by Gamblin. (Gamblin has terrific technical support, by the way).
Alkyds dry within 24 hours, so an adjustment to your approach to painting might
be in order. However, an alkyd medium mixed with oil paint works well if you use
a lot of transparencies and glazes, because layers can be applied overnight.
Alkyd mediums, such as Galkyd or Liquin are thick (though not as thick as a gel).
Galkyd Lite has been formulated as a thinner alkyd medium, although its open
time is similar to Galkyd #1. Gamblin also makes Galkyd Slow Dry which dries
slower than either Galkyd or Galkyd Lite.
Solvents for oil paints
The following is based on information provided by Gamblin Artist's Oil Colors. For
further information consult the Gamblin oil painting solvent comparison chart.
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Turpentine -- Before the introduction of mineral spirits, turpentine was the
only solvent available to oil painters. Unfortunately, this solvent is highly
toxic and can get into the blood stream through skin contact. Made from
distilled pine tree resin, turpentine is a strong solvent that dissolves damar
varnish. It should only be used only with adequate ventilation.
Mineral Spirits (paint thinner) is a petroleum based solvent. The toxicity
of this solvent varies depending on the amount of aromatic compounds it
contains. (Aromatic compounds increase the evaporation rate and
produce noxious fumes). Mineral spirits will not dissolve damar varnish.
This solvent is not recommended for use with artists' oils.
Odorless mineral spirits (OMS) is the least toxic of the solvents. Some
thinners sold in hardware stores are labeled odorless, but still contain
aromatic compounds. Artists should use odorless thinners that have the
lowest possible level of toxicity that do not produce noxious fumes. That is
why it is best to purchase odorless thinners from art supply stores.
Odorless mineral spirits is weak and does not dissolve damar varnish, but
can be used in painting mediums that contain most stand and sunthickened oils (Holbein sun-thickened oil will not properly dissolve in an
odorless thinner). Odorless mineral spirits is also suitable for cleaning
brushes and palettes. Nonetheless, this is still a toxic solvent and should
be used with adequate ventilation.
Oil varnishes
Varnishes for oil paints provide a transparent layer over dried paint. Varnishes
are primarily used to create an even gloss or matte finish over an oil painting and
restores the original brilliance of the color.
Traditional resins used for oil painting varnishes were derived from damar, a
natural resin made from Indonesian fir trees. Oil paintings should be varnished
after they are thoroughly dry. It is recommended that oil paintings dry for at least
6 months before applying a final varnish made with damar.
Damar Varnish Preparation - Artists can make their own damar varnish by
dissolving damar crystals into turpentine. Damar crystals can be purchased at art
supply companies like Utrecht or Daniel Smith. The crystals are placed in a
cheesecloth bag. (You can make a bag from a piece of cheesecloth tied at the
top with a string. I've found pre-made cheesecloth bags at homebrewing supply
stores). Suspend the bag into a measured amount of turpentine - usually about 1
part crystals to 3 parts turpentine by volume. The damar crystals do not
dissolve properly in odorless turpentine. The regular hardware store gum
spirits variety is best. Don't let the bag sink to the bottom. The turpentine will
dissolve the crystals in a few days. Expect some of the crystals to remain
undissolved.
Today, many varnishes and painting mediums sold for use in oil painting are
derived from alkyd resins. Alkyds were first used in the early part of this century
in industrial paints (polyurethane and other floor paints are alkyd based -- artist
quality alkyd paints are also available). Alkyds are very durable, but dry much
more quickly than oils. Alkyd varnishes and mediums for artists' oils are soluble
in odorless mineral spirits (unlike varnishes and mediums made with damar).
Gesso made with alkyd resin is also available.
Retouch varnish is used after the oil paint has dried to the touch to restore color
brilliancy. Retouch varnish is weak and allows air to penetrate to the paint layer
so oxidization can continue. Retouch varnish is available in art supply stores and
is often made with an alkyd resin.
Because of noxious fumes, all varnish preparation and application must be
done in well-ventilated areas (outdoors is best if you can avoid insects).
OTHER PAINTING MEDIA
Oil paint sticks - Oil paint is now sold in a solid stick form, allowing the artist to
draw with color onto a surface. Oil stick can be thinned with turpentine and can
be easily incorporated into the process of oil painting. Oil sticks work much like
oil pastel, but are richer in texture and color and, unlike oil pastel, will dry hard
and permanent. After use, a skin will form on the end of of the stick. This can be
shaved off prior to using the sticks again.
Alkyds paints - Traditionally used as industrial and house paints, alkyd paints
are soluble in turpentine or odorless mineral spirits, and can be used as an
underpainting for oils or mixed direclty with oil paint. Alkyds share characteristics
of both oil and acrylic paints; alkyds dry overnight, but can be blended and
modeled like oil paints for several hours. They handle somewhat differently than
artists oil paints, in part, because they have an even consistency regardless of
the pigment used. Alkyd paints also cannot hold as much pigment as oil paint,
and therefore, some alkyd colors are not as saturated. For information about
alkyd painting mediums used with oil, click here.
Water miscible paints - Paints that mix with both oil and water are now
available. One commonly used brand is the Grumbacher "Max" paints. These
paints handle somewhat differently than traditional oils but are less toxic (cleanup
is with soap and water).
Encaustics - Encaustics involve the mixture of dry pigments into molten
beeswax. Artists melt the wax in small metal containers on a hot palette or hot
plate. Pigments are added to the containers and the encaustic is applied to
surfaces with brushes and other tools. Encaustics may have originated in ancient
Egypt, and were used widely in ancient Greece. According to Ralph Mayer, the
ancient Greeks also used a form of encaustics to add color to sculpture. This
medium was rarely used during the renaissance, although the 18th century saw a
revival of encaustics in mural painting. Encaustic painting, however, is primarily
painted on the easel, and today many contemporary artists use encaustics in
their work, such as Flag on Orange Fieldby Jasper Johns. Wax is compatible
with oil paints and wax mediums are used in oils for impasto effects. (For
additional recipes, see encaustics at Sinopiaonline)
SUPPORTS
Flexible - Light and convenient, paper and especially canvas are by far the most
popular painting supports.
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Paper - Use only 100% rag (cotton) paper. Paper tape or staple (3" apart)
the paper to a smooth, stiff, and rigid backing like masonite or wood.
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Canvas - Linen, like linseed oil, is derived from the flax plant. It is grayish
in color and is considered best because of its durability and texture, but it
is very expensive. Cotton Duck (sailcloth) is of high quality and comes in
various grades and weights. Cotton duck (#12, weight: 11 4/10 oz.) is
superior in quality.
cotton duck #12
two grades of linen
Rigid - Rigid supports are nice surfaces on which to paint because of their hard,
flat surfaces. Their biggest drawback is their weight which can prohibit large
scale painting. Masonite should be glued overnight (wood carpenters or stronger)
to a wood frame using "C" clamps. This will keep the masonite rigid. Do not nail
masonite to its wooden frame. The nails will show on the front of the surface and
will rust. Quarter inch birch plywood panels should be similarly attached to a
wood frame.
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Birch Panels - Birch plywood is a popular rigid support for painters
because of its smooth surface and strength. It can also be obtained in
larger sizes (4' x 8' sheets max.). Birch used for paintings should be 1/4"
to 3/4" thick. Birch plywood is now available with a foam core which
reduces the weight of this material.
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Masonite - Tempered or untempered masonite panels are also available
in large sizes. Tempered masonite contains oily particles which make
sanding the surface necessary in order to hold acrylic gesso, gesso sotile,
or glue sizes. Tempered masonite is smoother, harder, retains its shape,
and isn't damaged as easily as untempered. The main drawback of
tempered masonite is its weight which can make it difficult to handle.
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Metals - (Copper, zinc, steel, aluminum). Oil painting can be done on
various metal surfaces, including copper, zinc, and steel. Thin oil paint can
create transparencies on metal surfaces. Acrylics may peel off polished
metal surfaces or oxidize certain metals. Aluminum is a surface which
works well for use with acrylics.
The Solid Groundcompany produces hand-crafted panels for use with pastels
and paints. The materials used in the panels are non acidic, non absorbent, and
will not warp. The panels are extremely durable and chemically stable.
PALETTES
Palettes are the surfaces on which paint is arranged and mixed. Glass
is the best palette surface because it is non-porous and can be easily
cleaned. A homemade palette can be made by cutting a piece of
tempered masonite and a piece of glass to the same size. The palette
should be large enough to mix generous amounts of paint. Paint the
surface of the masonite white (use acrylic gesso). After the gesso is dry,
tape the glass to the masonite with masking tape around all four sides.
Palettes can be cleaned with a razor scraper even if the paint has dried.
Acrylic and oil painters should organize their palettes because it will
make their painting more manageable and help achieve unity and color
consistency in the work. Many painters use several palettes for different
stages of the painting. A traditional modern palette looks like the Munsel
or Itten color wheels with the addition of browns, black, and white. A
small amount of each color is squeezed along the outside edge of the
palette. Mixing is done in the center of the palette. Since each artist may
have personal affinities toward certain pigments, not all palettes will look
alike, but in general, palettes should be arranged according to the
spectrum. This allows the painter to quickly and intuitively find colors on
the palette.
Artists who have a certain color scheme or effect in mind often limit the
number of colors used on their palettes. Examples of palettes used by
artists in western art can be found here. (Also see the palettes
described in Faber Birren's,The History of Color in Painting for detailed
analysis of palettes used by old master painters). Below is an example
of a full palette:
It is a challenge for acrylic painters to keep their paints from drying.
Palettes can be purchased with lids to keep moisture from evaporating.
Plant spray bottles also help to keep acrylics from drying. Separate
plastic or glass containers can be used to store premixed paint.
Disposable paper palettes are sometimes used by artists, but they can
become messy and are often more trouble than they are worth.
Notes on Palettes, Color Mixing, and Painting Techniques
The transparency of a color effects its appearance. Glazes appear
brighter than opaque layers of paint because light reflects through the
glaze. Transparent colors do not have the same covering power as
opaque paint. Painters can add portions of opaque color to transparent
colors to increase their opacity.
Simultaneous contrast is also important to consider in painting (read
Joseph Albers, The Interaction of Color). Cool and warm colors suggest
spatial relationships and complementary colors tend to intensify each
other when used side by side. A solid understanding of color theory will
give you better control of your painting.
Because pigments come from the physical world, unlike the theoretical
color of the color wheel, they may contain an undertone of another
color. Ultramarine blue, for example, has a reddish undertone, making it
a better blue to mix violets. Thalo blue, on the other hand, has a
greenish undertone, making it the blue most suitable for mixing bluish
greens. Mixing alizarin crimson with viridian (thalo green) will result in a
blue-gray, because the bluish undertone present in both these colors
becomes dominant, while the neutral created from the red (alizarin) and
green (thalo) pigments result in a complementary color mixture of gray.
With time, painters can quickly identify the color undertones present in
tube colors. Certain tube colors, such as cadmium yellow can be easily
mixed with other colors (reds and blues) to create oranges or greens.
Cadmium red, on the other hand, creates a nice red orange, but makes
a neutralized, dirty violet. This is why it is necessary to have both a cool
and a warm red in order to create a range from orange to violet. Rose
madder, crimson or naphthol red are examples of a cool reds. A similar
thing happens with blue, although cobalt blue is very balanced and can
create both blue-greens and blue-violets.
Painters intentionally create undertones by adding trace amounts of
color to create warmth or coolness. For example, black can be made
warmer with the addition of brown or cooler with the addition of blue.
White can be warmed with a tiny amount of yellow or yellow ochre or
cooled with a very small amount of blue.
VOCABULARY
Alla prima - A painting technique used by the impressionists where a work was
usually completed in one sitting with opaque layers of paint. (see Monet)
Analogous colors - Related colors that lie adjacent on the color wheel such as
blue, blue-violet, and violet. Analogous colors share the same primary color.
Binder - An ingredient in paint which allows it to bind to a surface. A drying oil,
such as linseed, is a binder.
Blending - The process of mixing adjacent colors to eliminate abrupt divisions
and create a smooth gradation from one color to the next. Because of their slow
drying time, oil paints are ideal for blending colors.
Chiaroscuro - An Italian term meaning, "light-dark", chiaroscuro refers to
substantial changes of light in a painting that contribute to creating dramatic
mood in a work. Chiaroscuro became popular in the baroque period. (see
Carravaggio)
Complement and Complementary Color - In color, any hue that is directly
opposite on the color wheel.
Dabbing - A painting technique used by impressionist painters where short
strokes of paint are applied to the surface. Dabbing was done in layers and
contributed to the flickering effect of impressionist works. (see Pisarro)
Fresco - Fresco is a type of mural painting done on fresh lime plaster. Pigments
are absorbed into the moist wall and become integrated into the surface. (see
the Sistine Chapel ceiling)
Gesso - Originally used in fresco painting, gesso referred to various mixtures of
coarse and smooth plasters that were applied in layers in preparation for
painting. Later, gesso (or gypsum) was added to rabbit skin glue to create gesso
sotile (soft) grounds for panel painting. Today, the gesso most artists use is a
blend of polymer emulsion and chalk.
Glazing - Is the process of layering thin transparencies of paint. Glazes create
luminous effects because light can pass through them and reflect back from the
surface of the painting. In oil painting, most glazes are made from a combination
of oil, damar varnish, solvent, and small amounts of paint. Today, many glaze
mediums are made with alkyd-based resins to allow for both low toxicity and fast
drying. In acrylics, glazes are made from a mixture of polymer media and small
amounts of paint. (see Dutch still - life painting: Jan Davidsz. de Heem)
Ground - The initial layer or surface of the painting which serves as a barrier
between the canvas and the paint. Gesso is a type of white ground. Grounds can
be textured, colorful, neutral, opaque, or transparent depending on the surface
the artists wants to use. Before the impressionists, most paintings were done on
a prepared ground, either imprimatura or toned.
Impasto - Impasto is a thick application of paint. Rembrandt used impasto for
highlights in a painting. This technique added both spatial and expressive
qualities to his work. Later, painters like Van Gogh used impasto throughout the
entire canvas. Today, acrylics are often used for impasto applications because
they dry quickly and are easy to cleanup. For more about a recent Van Gogh
exhibition, click here.
Intensity - is created by the density of pigment in a particular paint. Intense
colors are also known as saturated colors. Mixed colors tend to loose their
intensity -- which is why most painters prefer to use pure tube colors rather than
mixtures. (see Vermeer)
Local color - The "actual" naturalistic color of an object -- as opposed to
subjective color which is exaggerated or invented.
Matte - A dull surface as opposed to a shiny surface.
Opaque - An application of media that completely covers, for example, any
underneath drawing or color. The opposite of transparent, light cannot pass
through anything that is opaque.
Pulling - A painting technique whereby paint is removed by a rag to expose
areas beneath the outermost layer of paint. Pulling is also used to create marks
on a surface.
Shade - Colors which have been darkened by adding black.
Scumbling - A technique where paint is lightly dragged over a a dry surface.
Scumbling does not entirely cover the surface and allows underneath areas to
show through.
Tint - Colors which have been lightened by adding white.
Value - In art, the relative darkness or lightness of tints, shades, and colors.
White is the lightest, or the value with the highest key; black is the darkest, or the
value with the lowest key.
Varnish - A mixture of solvent and a resin, such as damar or alkyd. Varnishes
are used to create an even gloss or matte finish over a surface which restores
the original appearance of wet paint. In acrylics, pure gloss or matte medium
serve as varnishes.
Wash - A thinned paint made from a solvent (as in the case of oil paint) or water
(as in the case of acrylics). Washes are different from glazes, because they are
not made by adding more paint binder; such as linseed oil or acrylic polymer
emulsion. In painting with oils or acrylics, washes should only be used in the
initial blocking-in stages of the painting.
Wet in wet - A technique of painting when wet (or oily) paint is applied onto a wet
or oily surface. This is essential for blending colors. Painting is often done by
applying paint directly onto undried surfaces so blending and color mixing can be
done directly on the canvas rather than on the palette.
STRETCHING CANVAS
Cut the canvas large enough so that it can be stapled to the back side of the
stretcher on all four sides. This means that an extra three or four inches of
canvas on each of the four sides will be necessary. Place all staples on the back
of the stretcher about three inches apart from each other. Use 5/16" staples with
a staple gun. Begin by stapling the canvas at the center on one of the sides.
Stretch the canvas directly across from this staple and place another staple on
this side. Do the same for the other two sides of the canvas. After the first four
staples are in place, pull the canvas straight up, then toward the corner. Staple
from the center to the corner. Follow the same procedure diagonally across.
Repeat until you have worked around the entire stretcher.
It may be necessary to pull out staples and re-staple to get the canvas tight. On
large canvases, temporary corner staples might be necessary, after the four
center staples are in place, to help hold the canvas on the stretcher. Excess
canvas should be cut from the back. The edges of the stretched canvas should
be smooth and gessoed along with the front of the canvas.
Corners should be saved for last and are neatest when folded like the
corners of sheets on a bed. Smooth corners are easier to frame.