Chemical analysis of dyes on an Uzbek ceremonial coat: Objective evidence for artifact dating and the chemistry of early synthetic dyes

• In-depth study of dyes used on a Uzbek man's coat from early 20th century.
• Identification of 42 synthetic dyes and 17 naturally occurring dyes.
• Dating of historical textile by the patent dates of synthetic dyes.
• Chemical basis for dyer's palette and the chemical profiles of early synthetic dyes.

A silk cross-stitched man's overcoat in traditional Uzbek style in the Indianapolis Museum of Art was thought to originate from late 1800s to early 1900s. To shed light on its history and associated textile dye chemistry, threads from the coat were subjected to dye analysis by LC-DAD-ESI-MS. Dyes identified include seventeen natural colorants from barberry, larkspur, madder and cochineal, and forty-two synthetic compounds in the diazo, xanthene, and triarylmethine class. Many of the synthetic dyes were heterogeneous, attributable either to crudeness in synthetic process or to age related degradation. The different shades of red and green in the threads were obtained from blending two or three synthetic dyes as well as, in one case, the combination of natural and synthetic components. Direct Red 23, C.I. 29160, first reported in 1900, was the most recent, thus refining the creation date of the garment to the early twentieth century or later.