Deep Rose Madder is a is a very dark red which is known in the chemical industry as benzimidazolone red. It is made in vast quantities and used mostly for coloring plastics, water based paints, inks, and is used in the textile industry for printing designs onto textiles. It is similar in color to alizarin crimson and can be used in a similar way on the palette but it share none of alizarin’s bad characteristics. Deep Rose Madder is highly permanent, comparable in permanence to Cadmium Red. Benzimidazolone is one of the azo pigments as can be seen from its name. The azo pigments is a large family of organic pigments in the yellow, orange, and red part of the spectrum. With such a large family it can be expected that some colors that share this name are not as permanent as others. The very best of them, and Deep Rose Madder is an example of this, easily match the cadmiums in permanence, and in some cases are actually more lightfast in tints with white.
Chemical Description: Benzimidazolone
Pigment Number: PR175
Lightfastness Rating: ASTM I
Pigment Opacity: Transparent
Paint Opacity: Transparent