ACRYLIC
PAINTING 101

For hundreds of years, artists’ paints were made from natural binders like linseed oil, egg, casein, and gum arabic. The property of each binder presented limitations or restrictions. In essence, characteristics associated with each type of paint were dictated more by the binder than the artist, forcing the artist to work, more or less, in traditional ways. All that changed in the 1950s.

You find polymers, or “plastics,” in everything you use from your socks to milk cartons. Though polymers were not created for the art materials industry, we are the beneficiaries of decades of trial and error, and technological advancements.

Polymer is a manmade, synthetic resin material.
Today, the term acrylic is most commonly used to identify artists’ colors made with acrylic polymer emulsions. In addition to polymer emulsion, acrylics may contain wetting agents, defoamers, preservatives, thickeners, and glycols for stability, pH balancers and filler. In their natural state, polymer emulsions are liquid and have a milky white appearance. When exposed to air, the water portion of the emulsion, which has held the synthetic resin particles in suspension, begins to evaporate. As water leaves, the particles draw tightly together (coalesce). When the emulsion is completely dry, a water-clear, tough, flexible film remains. The dry film is impervious to water, and for practical purposes, waterproof.

The unique characteristics of polymer resin binders have given artists:

Adaptability: When used straight from the tube, acrylics have the feel and response of oil colors. They may be thinned with up to 20 percent water and used to create watercolor-like washes and still retain their basic qualities. They can be applied thickly in layers as an impasto. Impasto is much like spreading frosting on a cake with a spatula. They can be used for underpainting and over-glazing.
Creative versatility: This is what makes acrylics extremely popular. Collage techniques and adhesion of objects, integration of texture and built-up relief add dimension and sculptural aspects to acrylic paintings.
Quick drying time: Relative drying time is dependent on thickness of the paint, and the amount of water or other additives; acrylics may dry to the touch in as little as 20 minutes. While thickness of paint (as well as humidity and temperature) affect drying time, acrylic paintings dry much faster than oil paintings.
Yielding: The flexibility of polymer emulsion allows acrylic to be used on a wide range of supports from wood, canvas, cloth and fabrics, to metals, leather and other plastics. Acrylics adhere to almost any non-greasy, non-oily surface.
Longevity: Acrylics have proven to be reliable. The emulsion does not yellow or become brittle with age. High-quality, light-fast pigments are used for artists’ grade acrylics as for other painting mediums.
Insolubility: After acrylics have dried, they are insoluble in water.
Easy clean up: Acrylics clean up easily with water, as long as the paint is still moist. No solvents are needed.

Viscosity
Viscosity (a term for the thickness of a material) is a term closely associated with acrylics, which are always sold in some type of liquid-like form. Once dry, or even partially dried, they cannot be reconstituted. An artist can change the viscosity of paint with additives.

Light or Low Viscosity: Very fluid. Light viscosity or liquid acrylics are made specifically for artists who want paint that is very fluid. When acrylic from the tube is thinned with a lot of water, the polymer binder is weakened. Adhesion to the painting surface is poor. Intensity of the color is lessened as pigment is dispersed in a greater volume of water. Liquid acrylic is formulated to retain intensity and strong adhesion.
Heavy or High Viscosity: The stuff that comes out of a tube. It is the choice for thick painting techniques. Paint tends to retain brush strokes or whatever shape it is put in. Palette and painting knives are great with these heavy-bodied paints. Mediums can be used to change it to a medium or light viscosity paint, or give to it more volume, or to make it transparent.

Student Acrylics
By adjusting the ratio of pigment to filler, or eliminating expensive pigments, manufacturers can provide a wide range of acrylics at non-intimidating prices. Price is a reality for the beginner who is not sure if they really “want to paint,” the student on a budget, or an artist who is value-conscious. Student acrylic has become a common term for a range of paints in which all colors sell for the same price regardless of color. Some manufacturers may offer a second tier of colors to include cadmiums and cobalt colors made from more expensive pigments and sold at a slightly higher price.

Artist Grade
Artist or professional-grade acrylics have become common terms for paint deemed the finest or best. Beyond the obvious price difference, what makes them different? To begin, manufacturers may use a higher quality of pigment in their artist-grade colors. Often, there is more pigment in ratio to the vehicle. Artist grade color is more brilliant, cleaner and clearer because they may be single pigments or there is less filler. The formula for the emulsion may provide stronger adhesion, and dry clearer. Manufacturers tend to support their artists’-quality paint with more information either on the label or with a brochure. The artist can read what’s in the tube. There are no “mystery pigments” that might cause mixing problems. The color range is more extensive. This usually creates additional price categories to compensate for diverse cost of pigment.

Hue is Back Again
Just like “hue on a tube” for watercolor, hue in conjunction with a color name on a tube of acrylic means that an alternate pigment (or pigments) has been used to replicate the original pigment. It is done for the same reasons: economics, scarcity or toxicity of the original pigment, or an alternate pigment offers a beneficial property that the real pigment lacks.

The White and Black of Acrylics
Two whites are commonly found in acrylics: titanium and zinc. Titanium is an opaque white for mixing pastel tones. Zinc is more transparent and used for tinting and glazing. Within all the acrylics on the market, you will find a number of black options: mars, ivory, carbon and black. Out of the tube, there may be little difference. When black is mixed with other colors, used with white or thinned, it shows subtle differences. Mars black tends to be warm (brownish), ivory tends to be cool or have a slight blue bias.
A color named “black” or “white” might be anything. If there is no pigment information on the label, the artist will need to test it to see if it will give the desired results.

From NAMTA’s Art Materials Essential Reference Guide.
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