M. Graham Artists' Oil Color - Azo Coral, 37 ml tube

Pigment Information

This color contains the following pigments:

PO62-Benzimidazolone Orange

PR254-Pyrrole Red

Pigment Name

PO62-Benzimidazolone Orange

Pigment Type

organic, monoazo

Chemical Formula

C17H13ClN6O5

Properties

Benzimidazolone Orange is a staining, yellowish orange pigment that can become dull in tints. It has an average drying time, and it loses some of its intensity as it dries. The yellowish orange varieties are more transparent.

Permanence

Benzimidazolone Orange has excellent lightfastness and outstanding heat and solvent stability for a monoazo pigment.

History

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. Use of benzimidazolone pigments in the auto industry, especially Benzimidazolone Orange, became common in the 1980s because they were common replacements for lead chromate pigments, which were phased out during this period.

Pigment Name

PR254-Pyrrole Red

Pigment Type

organic, aminoketone

Chemical Name

Bis-(p-chrolopheny)-1. 4-diketopyrrolo(3. 4-c)pyrrole

Properties

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.”

Permanence

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.

History

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.