Naphthol Red Dark
PR23
Alternate Names
Naphthol Red Dark AS-BS
Naphthol Red Blue Shade
Pigment Description
Naphthol Red Dark is one of several napthols out there. A pigment whose lightfastness descends to ASTM IV or even ASTM V in gouache- the lowest lightfastness category for artist paints- is also flagged for potential health problems. It is currently found in six acrylic paints made by major manufacturers and at least one watercolor.
In Monona Rossol's writing, this is a suspected carcinogen, and has caused kidney damage in rats, along with metabolizing to cause something related to methemoglobinemia, so please consult her work for more information.
Resources
PR23 pigment data from David G. Myers, The Color of Art Pigment Database, Artiscreation.com
Information about PR23 from Bruce MacEvoy, Handprint Guide to Watercolors, General information about this class of pigments from Handprint,
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
Poor, may be as low as ASTM IV
Transparency
Semi-Opaque, Semi-Transparent, Transparent
Transparent but also available as a semi-opaque pigment
Toxicity
Lower Concern
More information at artiscreation.com. Treat all pigments and paints with studio safety protocols.
Chemical Name
Monoazo: 3-hydroxy-2-naphthanilide
C₂₄H₁₇N₅O₇
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