What information should be on the label of a tube of paint? Presumably, prospective buyers would want to read about what is inside the tube, such as the pigment, medium (oil or acrylic, for instance), other admixtures (additives, binders, coarse particle content, extenders, preservatives) and the durability (or lightfastness) of the product. Art supply companies are also required by federal law to indicate which ingredients are known to cause either acute or chronic illnesses ("...has been shown to cause cancer"), what those ailments are and how the product should be used properly as well as the name, address and telephone number of the manufacturer.
Unfortunately, not all art supply makers provide all this, and many offer bits and pieces of information, often using proprietary names and terms or codes that mean different things to different manufacturers.
One area of potential confusion are paint pigments described as, for example, Cobalt Blue "hue" or Cadmium Red "hue." The paint pigments that are labeled hues are usually substitutes, such as ultramarine for cobalt or thioindigold red for cadmium, or laboratory-created colors. To a significant degree, synthetically produced pigments are a result of permanency and price. Certain colors, such as alizarine crimson or Hooker's Green, are terribly fugitive and tend to fade quickly. The color ingredients used to replace the traditional pigments are said to make these colors much more permanent. The cost of other pigments, such as cadmium and cobalt, for example, has become so high that artists just wouldn't be able to afford them.
Prices for the synthetically produced "hues" are between two-thirds and one-half the cost of the real thing. In one art supply store, the retail price for a small tube of Winsor & Newton Cadmium Red Medium was twice the cost of its Cadmium Red Hue, and Liquitex's Cerulean Blue cost 30 percent more than the Cerulean Blue Hue. The permanency rating for the "hues" is largely the same as the traditional colors they might substitute for and the colors will not be identical.
The cadmium red hue and the cobalt blue hue, for instance, shift a bit to the violet, while phthalocyanine sometimes shifts to green. If they choose paints with synthetic ingredients, artists will pay less, but they'll have to be more observant, correcting the color shifts by adding yellow to the cadmium hue and green to the cobalt hue. The hues are not the same, and artists find themselves having to work harder to preserve what they thought they had.
Perhaps, between 20 and 30 percent of all professional artist paints contain synthetic pigments, increasing to perhaps 40 percent for supplies just under artist grade, with almost all student grade paints being substitute ingredients.
The synthetic pigments clearly have benefits and some drawbacks -- or, at least, give rise to new battles among art supply manufacturers. The more expensive iron oxides, such as burnt siena, Indian red or yellow and raw umber, are literally dug out of the ground and tend, because of their source, to have impurities. The lab-created pigments, on the other hand, have few impurities and also a higher tinting strength, requiring the addition of inert pigments -- such as aluminum hydrate, berium sulphite and calcium carbonate -- to tone down the color. The result is that the new generation of paints tend to have less cadmium in cadmium, less cobalt in cobalt, with other ingredients added -- such as enhancers or toners -- for opacity, body, consistency, brightness, value and to eliminate excess oil. All this requires artists to assume less about the paints they use and to learn more about what goes into their supplies.
This becomes a problem because not all manufacturers of artists' materials label their products in the same way. Part of the system established for labeling by the Philadelphia-based American Society of Testing and Materials requires manufacturers to list on the product label the enhancers used when they comprise more than two or three percent (by volume) of the material. Not all American companies, however, subscribe to the ASTM standard, and few European suppliers do. The result is that artists may find themselves purchasing what is labeled as pure cadmium but that actually contains a considerable amount of toner (dye color). It is a concern for which few artists or hobbyists these days are prepared.
The hues and proprietary color descriptions are obviously one example. Most tubes of artist paints include a number that corresponds to a standardized Color Index, a nine-volume reference that is jointly produced by Society of Dyers and Colourists in England (P.O. Box 244 Perkin House, 82 Grattan Road, Bradford West Yorkshire BD1 2JB) and the American Association of Textile Chemists and Colorists in the United States (One Davis Drive, P.O. Box 1215 Research Triangle Park, NC 27709-2215). One may also contact the American Society of Testing and Materials (100 Barr Harbor Drive, West Conshohocken, PA 19428, 610-832-9500) for precise descriptions of pigments and the durability of pigments.
Permanency ratings is another area in which one might contact the manufacturer for more information if the label is not clear or decipherable. The American Society of Testing and Materials rates paints I, II and III for their resistance to fading in daylight, or lightfastness, with I the most resistant. Liquitex follows the ASTM format in its lightfastness ratings, but Van Gogh's ratings are +++ and ++, with +++ the highest degree of lightfastness and ++ what the company calls "normal degree of lightfastness." Rembrandt lists lightfastness, starting with the most permanent, as A, B, C and D. Winsor & Newton has two different rating systems, ++++, +++, ++ and +, on the one hand, and AA, A, B and C (++++ and AA are the most lightfast), on the other hand.