Manufacture
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(Excerpts from ART HARDWARE: The Definitive Guide to Artists’ Materials, by Steven Saitzyk © 1987) The manufacture of polymer emulsion paints is a balancing act. Mixing dry pigment directly into a polymer emulsion rarely creates a usable paint. Several additives are needed to produce a workable paint. The polymer solids must be coated with emulsifiers to prevent them from binding together before the liquid evaporates. Dispersants are necessary to keep the pigments that are added from clumping together and/or settling out of the liquid. Antifoaming agents are needed to prevent foaming during the application of a paint so that the dried paint film does not have a craterlike surface. Wet-edge agents, such as ethylene glycol (very poisonous) or propylene glycol (less effective, but nontoxic), are used to regulate the drying time, allowing sufficient time for mixing and applying the paint. Thickeners are used to transform the milky quality into a paintlike consistency. And last but not least important, a preservative is added. The type of paint film that is formed depends on the specific polymer formulation used. For example, the Rohm and Haas Company, the supplier of acrylic emulsion to all paint manufacturers in North America and many parts of the world, offers several varieties of 100 percent acrylic emulsion (of which 44 and 47 percent of the emulsion is composed of resin solids). Rhoplex is the name it has given to its acrylic emulsion and each formulation is assigned its own number. The most commonly used emulsions that are dispersed in water are AC-22, AC-33, AC-34, AC-35, and AC-235. (There are also acrylic solutions such as Acryloid F-10, which is 40 percent resin solids in mineral thinner which are used in the manufacture of paint varnishes and acrylic paints that can be thinned with mineral spirits.) AC-22 has good flow and leveling properties, but is less durable than the other formulas. AC-33 was the first formula used in the arts and is still commonly used. AC-34 was designed for outdoor use on wood, but tends to be slightly more brittle. AC-235, the improved version of AC-35, is used to give paint a thicker quality and would be used in impasto painting. Since each of these formulas has desirable qualities as well as undesirable qualities, most paint manufacturers blend the various polymers like chefs to obtain, what is in their opinions, the best working characteristics. A blend of more than one polymer is referred to as co-polymers; virtually all artist acrylic and vinyl paints are co-polymers. The physical process of making acrylics resembles the process one would more expect to see in a pastry shop than in a paint mill. Some manufacturers do not use rollers to grind the paint mixture as would be done with oil paints, but simply mix the ingredients together. Mixed paints are less desirable for airbrushing and for watercolors where fine dispersion is important. (Excerpts from ART HARDWARE: The Definitive Guide to Artists’ Materials, by Steven Saitzyk © 1987)
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Questions regarding materials and the
creative process will be considered a request for a consult and
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