The purple coloration of four late 19th century silk dresses: A spectroscopic investigation

•The development of purple synthetic dyestuffs was achieved during the 19th century.•Four purple silk dresses from this period were studied to determine the dyes used.•Using SERS, three of the dresses were found to be dyed with methyl violet 2B.•Warp and weft yarns from the other dress were mordanted with tannic acid and tin.•The warp yarn was dyed with methyl violet 2B while the weft yarn was with mauve.

Prior to the 19th century the use of purple dyes for textile coloration was expensive and usually limited to royalty. The discovery of several synthetic purple dyes during the 19th century made the production of purple textiles more affordable and thus more readily available. The identification of the source of the purple coloration is of historical interest. Small yarn samples from four late 19th century silk dresses were analyzed using a combination of thin layer chromatography and surface enhanced Raman spectroscopy, Fourier transform infrared spectroscopy and energy dispersive x-ray spectroscopy. This combination of techniques enabled the analysis of the complex extraction products. While three of the dresses were found to be dyed using methyl violet, the fourth dress was found to be constructed from a warp yarn dyed with methyl violet in the presence of a tannic acid mordant, and a weft yarn dyed with mauve and a tin mordant.

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