Benzimidazolone Orange HSL
PO36
Alternate Names
Benzimidazolone Orange HL
Benzimidazolone Scarlet
Pigment Description
Offered by four major oil paint manufacturers as a single-pigment color. The lightfastness for this color varies widely according the supplier. It would be advisable to do lightfastness tests if it is a color you like to use. From some pigment suppliers the lightfastness is excellent, and for others it is merely moderate. Williamsburg describes their version as, "Strong, somewhat sour, tomato-like red orange," and cites the ASTM I rating.
However a word of caution is needed. Though it was previously thought to be of low concern for toxicity, Monona Rossol's work mentions that this is one of the pigments which may metabolize to cause a condition called methemoglobinemia-- please consult her work on pigments for more information.
Resources
PO36 pigment data from David G. Myers, The Color of Art Pigment Database, Artiscreation.com
Information about PO36 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
Varies
Depending on the manufacturer this color may be excellent or it may be only moderate. If you are using this color it may be advisable to do your own lightfastness tests. Many varieties have a slight falloff in tints (7’s on the BWS), but some show solid high marks (all 8’s).
Transparency
Opaque, Semi-Opaque, Semi-Transparent, Transparent
Toxicity
Previously thought to be in the category of Low Concern (with notes to avoid dust and spray), new research suggests this may metabolize to cause a serious health condition.
May metabolize to something that could cause methemoglobinemia. See Monona Rossol's research available upon request here for more information. Treat all pigments and paints with studio safety protocols.
Dry Time
Medium
Average, 2-5 or 2-7 days in oil
Chemical Name
monoazo, acetoacetyl, HL
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