Hansa red

Description

Originally a Hoechst AG trademark for a line of bright, transparent red synthetic organic pigments. Hansa reds, also called toluidine reds, are based on the reaction of beta-naphthol with 2-nitro-4-toluidine. Toluidine red was first synthesized in 1905. In general, toluidine reds have fair lightfastness and weather resistance, and they have a tendency to bleed. They are used in industrial coatings for air-dried and baked enamels and auto finishes. Toluidine reds are also used in wax crayons, pastels and watercolors.

See also Hansa.

Synonyms and Related Terms

toluidine red; Pigment Red 3; CI 12120

FTIR PR4(MFA)

Comparisons

Pigment number (CI)	Pigment name	Manufacture	Comments
PR3 (12120)	Hansa Red3B, Toluidine red	discontinued	often a dark, intense red shade
PR4 (12085)	Hansa Red R-D, Chlorinated, para red, Toluidine red	unknown	yellowish-shade red
PR003 ()	Studio red, helio	Kremer (#23950)
PR004 ()	Hansa red R (beta-naphthol)	unknown	sample from Tate Collection

Risks

• Ingestion can cause cyanosis.
• Suspected carcinogen.

Physical and Chemical Properties

• Hue: ranges from yellowish-reds (like scarlet or fire engine red) to bluer reds (closer to crimson or ruby).
• Transparency: relatively transparent to semi-opaque
• Tinting strength: good to very good
• Lightfastness: early colorants had fair lightfastness, while more recent formulations have improved
• Stability: soluble in many organic solvents; resistant to acid, alkali and soap; not bleed resistant; very good heat resistance

Resources and Citations

• Richard S. Lewis, Hawley's Condensed Chemical Dictionary, Van Nostrand Reinhold, New York, 10th ed., 1993
• Michael McCann, Artist Beware, Watson-Guptill Publications, New York City, 1979
• Monona Rossol, The Artist's Complete Health and Safety Guide, Allworth Press, New York, 1994
• B. Berrie, S.Q. Lomax, 'Azo Pigments: Their History, Synthesis, Properties and Use in Artists' Materials', Studies in the History of Art , National Gallery of Art, Washington DC, No. 57, 1997