This color contains the following pigments:
Bis-(p-chrolopheny)-1. 4-diketopyrrolo(3. 4-c)pyrrole
Pyrrole Red is opaque and has strong covering power. According to manufacturer Ciba, which uses the trade name Irgazin Red, it is a “clean, highly saturated mid shade red with high temperature resistance, excellent color strength, outstanding chemical, solvent and bleed resistance, and good weatherfastness.”
Pyrrole Red is considered to have excellent lightfastness among organic pigments in its class. Tests in industrial applications have given it scores of 7-8 on the Blue Wool Scale.
According to the Australian government's Ministry on Health and Aging, "The notified chemical exhibited low oral and dermal toxicity in rats, did not exhibit toxic effects when administered orally to rats for 28 days, was not a skin irritant in rabbi
Pyrrole Red, used as an automotive paint and as a colorant in plastics, was developed as one of a range of pigments to replace lead based pigments. In art materials, it is often used as a synthetic and lightfast replacement for carmine, a laked pigment that was originally produced from the body of the cochineal insect. It is also used to replace the older naphthol reds, organic red pigments that are sometimes only marginally lightfast and weatherfast.
Benzimidazolone Carmine is a staining, dull red transparent pigment with high tinting strength. Its color is similar to, although somewhat darker than, Rose Madder, the natural source of the historic color Alizarin Crimson. Because it stains and tints much more strongly than natural Rose Madder, care is required to achieve the same effects.
Although it is not absolutely lightfast, Benzimidazolone Carmine has excellent lightfastness for a transparent red organic pigment, and as a result, it is often chosen as a more permanent pigment to replace Alizarin Crimson.
Benzimidazolone Carmine is not considered toxic.
The benzimidazolone group of pigments was developed and patented in 1960 by Hoechst A.G., a German chemical manufacturer that was a forerunner of the pharmaceutical company Aventis. They differ very widely in hue.