PG 12 – naphthol green – Cultural Heritage Science Open Source

PG 12 – naphthol green

Created in 1883 by Otto Hoffmann and still in use. It is mostly applied in the textile industry and coloring paper but has been used also for artists’ supplies (Windsor & Newton watercolors) from its early discovery. Though it is not among the most stable green dyes, it was appreciated in order to replace the even less lightfast natural green colorants.

Manufacturer/ product code: Sigma-Aldrich / N7257
Chemical description: iron complex of 1-nitroso-2-naphthol-6-sulphonic acid. C30H15FeN3Na3O15S3 . Acid Green 1 (C.I. 10020, AG1) Sigma-Aldrich CAS: 19381-50-1
Color: green
Color Index: PG12
More info:

W. Neugebauer, et al., Naphthol Green – a forgotten artists’ pigment of the early 20th century. History,
chemistry and analytical identiﬁcation, Journal of Cultural Heritage (2018).