The Blue That Once Was: Preparation of Aniline Blue Model Fabrics for Investigating the Light-Fading Characteristics of the Historic Textile Dye

Aniline blue is among the early synthetic organic dyes that became commercially prominent in the late 19th century due to their brilliance and wide range of colours, despite their reputation for low fastness. The literature suggests its popularity and likely presence in historic textiles from this period. This paper discusses the study leading to the preparation of model fabrics that were to be used for investigating the dye’s light sensitivity, including understanding the history, nomenclature and chemical constitution of aniline blue, as well as the procedure and results of the actual reproduction of a historical dyeing recipe. To clarify the terminology used in recipes from the 19th century and to inform the chosen dyeing procedure for the model fabrics, descriptions of the dye from manuals from the period were compared to those of more recent references, including handbooks and chemistry textbooks. Drawing from literature from different time periods, aniline blue molecules are di- or triphenylated derivatives of rosaniline homologues found in the magenta dye. Dye manuals written shortly after 1860 refer to three types that vary in solubility and application method: spirit blues, soluble blues and alkali blues. Pieces of silk were dyed with reagent-grade Acid Blue 93 (CI 42780), established as a modern equivalent of a soluble blue, following a corresponding recipe from 1885.