Back to black (II): Reproduction and evaluation of historical black dyeing (1700–1899)

This study presents a systematic experimental reconstruction and quantitative evaluation of black dyeing techniques applied to wool, silk, and cotton textiles, based on recipes documented in 18th and 19th century dye manuals. Thirty-one samples were produced using historically significant methods, including iron-tannate complexation, logwood- and copper-based lake formation, and subtractive color mixing on indigo or fawn grounds. Comprehensive colorimetric analysis ( K/S , CIELAB) revealed that black produced on blue grounds consistently achieved the highest color intensity across all fibers, while iron-tannate overdyes yielded the deepest shades but also caused substantial fiber degradation. Tensile testing and accelerated UV aging, conducted under simulated museum conditions enabled assessment of both immediate and long-term physical stability. Iron-tannate dyeing resulted in the greatest tensile loss, up to 20% following UV exposure, due to the combined effects of acid hydrolysis and iron-catalyzed oxidative stress, with silk exhibiting the highest sensitivity. In contrast, subtractive mixing and indigo-based methods produced stable shades with comparatively minimal fiber damage. These findings elucidate the trade-offs between chromatic depth and mechanical stability inherent in historical black dyeing processes and clarify the chemical and photochemical mechanisms of fiber degradation, including metal-catalyzed radical formation. The results provide practical data for heritage textile conservation and inform the sustainable development of high-performance natural black dyes for modern applications.