The dyer dyed
Tyrian purple, indigo and arsenic green on dress: sources, chemistry, process and names, told as history, with what tests on surviving cloth can show.
3 entries so far
Tyrian purple came from sea snails. In most species analyzed, its main pigment is indigo with two bromine atoms. What Aristotle, Pliny and a dye test show.
"Murex brandaris" by Wenceslaus Hollar — https://commons.wikimedia.org/wiki/File:Wenceslas_Hollar_-_Murex_brabdaris.jpg — Public domain (Wenceslaus Hollar d. 1677, PD in US and EU)
Indigo won't dissolve in water. An alkaline vat turns it into a leuco form that dissolves there; the fermentation vats studied went yellow-green. Air turns cloth blue.
"Indigo plant (Indigofera tinctoria L.): flowering stem with separate flower and fruit segments" by Wellcome Collection — https://commons.wikimedia.org/wiki/File:Indigo_plant_(Indigofera_tinctoria_L.);_flowering_stem_with_Wellcome_V0042997EL.jpg — CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/)
An 1861 inquest blamed arsenite of copper for a flower maker's death. Writers warned about wearers but named none; only a test shows which dresses held arsenic.
"The Arsenic Waltz" by Wellcome Collection — https://commons.wikimedia.org/wiki/File:Two_skeletons_dressed_as_lady_and_gentleman._Etching,_1862._Wellcome_V0042226.jpg — CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/)
;_flowering_stem_with_Wellcome_V0042997EL.jpg){kind=link}
