What About Organic Pigments?

Over the past several decades, organic pigments have often supplanted inorganic pigments in areas where a high performance paint is required. In general, organic pigments are less likely to have heavy metal impurities such as cobalt, nickel, copper and chromium. However, organic pigments have their own concerns, and their usage should be evaluated closely by any artist wishing to use them.

Contamination in the manufacturing process is the number one issue when dealing with organic pigments. The largest group of organics, known as “Azo”, includes specific pigments that are now known to release the carcinogenic amine dichlorobenzidine, as well as other carcinogens. PR 122 (Quinacridone Magenta) is prohibited by some regulations in Germany because it releases the carcinogen benzene when heated to high temperatures. One pigment manufacturer now offers a replacement for PR 122, that is made using a less toxic, but more expensive process. PV 23 (Dioxazine Purple) is also banned for certain applications for the same reason. PG 7 (Phthalo Green) is considered a “moderate” toxicity concern, but is perhaps the single most problematic pigment because it is the hardest of all to replace.

One issue with knowing what is in an artist paint is pigment identification. It is common for a single pigment to be listed and sold under many different product names. For example, PB 15 (Phthalo Blue) may be called Helio Blue, Peacock Blue, Brilliant Blue, or one of thirty other names. To avoid confusion, the paint industry uses Color Index numbers such as PB 15 to refer to all Phalo Blues. The Color Index system is not perfect, as there are shade variations for any specific color, but it is an essential first step. Some pigment suppliers actually mix different pigments together before they are sold to the paint maker. This makes it very challenging for the artist. For that reason, any paint that does not clearly indicate the Color Index (CI) number on the packaging should be viewed with suspicion.

Recently, several pigment manufacturers have been working to improve their products by reducing contamination. The newest product information sheets show a much fuller analysis of contaminate levels for heavy metals as well as aromatic amines that are used in the manufacturing process. For the artist, this is good news. If the paints offer a full disclosure of contents, including and especially the Color Index number, the artist can better evaluate the paint and thereby avoid the most problematic pigments.