Toluidine Red
PR3
Alternate Names
Studio Red
Hansa Red
Segnale Red
Pigment Description
This abominable color has a blue wool scale of 3/8 (about ASTM IV category). If you are new to this, the way it works is higher the blue wool scale on a scale of 1-8 the better- eight is the best. For us, sevens mean moderate. Sixes are lower than we would use. A three for lightfastness is quite low.
Toluidine Red comes in three different varieties, light, medium and dark.
In terms of health, Monona Rossol also writes that it may be a carcinogen as well as about potential serious health issues that could arise, so please consult her writing if you choose to use it.
Resources
PR3 pigment data from David G. Myers, The Color of Art Pigment Database, Artiscreation.com
Information about PR3 from Bruce MacEvoy, Handprint Guide to Watercolors, General information about this class of pigments from Handprint, More 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
For us, even a rating of ASTM III is too low for artistic use (some consider III to be the dividing line), but this pigment can sink lower. Lightfastness may range from ASTM II to IV, and the Blue Wool Scale (BWS) tests reported on Artiscreation show fading down to a 3. (For context the BWS is a scale of 1-8 ,with 8 being desirable). BWS 3 is far too low for consideration in archival work. Other sources report that tints are said to fade appreciably after 1 year of outdoor exposure in Florida sunlight.
Transparency
Semi-Opaque
Generally listed as semi-opaque, but there are different versions of the pigment. It comes in transparent and opaque versions as well.
Toxicity
Previously thought to be in the category of Low Concern, new research suggests this may be a carcinogen.
This pigment may cause methemoglobinemia, and it may be a carcinogen. See Monona Rossol's research available upon request here for more information, as well as artiscreation.com
Dry Time
Unknown, but may be slow
Reported to be a poor drier
Oil Content
Varies from moderately low to high
May be on the higher end of moderate. Depends on formulation. By weight, Artiscreation lists approximately 40g/100g of oil, but your pigment may have different requirements.
Chemical Name
Monoazo, 2-naphthol
C₁₇H₁₃N₃O₃
DISCLAIMER: Please note that we are not experts in health and safety and we are not toxicologists, please consult the proper experts. We are not liable for any issues that may arise from the use of our website or its contents. The information contained in this site is provided without warranty or guarantee of any kind. We do not necessarily endorse any other website that are linked from our site. For any important pigment specs, please reference the manufacturer details. If you discover errors or omissions, please reach out through our contact form. Thank you.
