Benzidine Orange
PO13
Alternate Names
Pyrazolone Orange
Permanent Orange G
Pigment Description
Low lightfastness and also toxicity issues. Monona Rossol writes that it may be contaminated with PCBs --also please see her work regarding issues with a cancer causing compound (we advise artists to research benzidine in artist pigments). Unfortunately, a reputable artist pigment manufacturer uses this as a single-pigment imitation of Cadmium Orange. It also crops up in a handful of convenience blends- at least six- by another paintmaker. This color has shockingly low lightfastness in tints, as low as 3 on the Blue Wool Scale.
Resources
PO13 pigment data from David G. Myers, The Color of Art Pigment Database, Artiscreation.com,
Rossol, Monona. The Artist's Complete Health and Safety Guide. New York, NY : Allworth Press, 2001. The book is rather dated, updated information is available from her website.
Stats
Lightfastness
Poor
The NPIRI from the 80s noted slight change in masstone during outdoor exposures and an appreciable fall change in tints. This color is not lightfast enough, as it is the low end of moderate to poor. May fall to BWS 3.
Transparency
Transparent, Semi-Transparent, Semi-Opaque
Toxicity
Hazard, may also contain PCBs as contaminants
Monona Rossol’s work notes that heating this pigment may release cancer-causing 3,3’-dichlorobenzidine, and it could metabolize to that as well. In the 1980s, the NPIRI mentioned that trace amounts of PCBs may be contained in this pigment, which is also echoed in Rossol. Her work is available by here. She writes, “Benzidine is known to cause bladder cancer. And all benzidine pigments and dyes that metabolize or decomposed to release free benzidine are expected to cause this disease…”
Chemical Name
Disazo
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