On the role of tannins and iron in the Bogolan or mud cloth dyeing process

Abstract

We have investigated the chemistry of the Bogolan or mud cloth dyeing process, a traditional technique of coloring cotton cloths deeply rooted in Mali. Textiles produced by the traditional Bogolan process, using tannin-rich plant extract and iron-rich clay-based mud, were compared using infrared (IR) spectroscopy, scanning electron microscopy (SEM) and X-ray absorption near-edge spectroscopy (XANES) with cotton fibers that were impregnated with tannin and iron salt solutions. IR spectroscopy in both reflective mode on the cloth and cotton and in transmission mode on single fibers, together with SEM, showed that gallic and tannic acid adsorb and precipitate onto the cotton fiber surface. IR spectroscopy and comparison with tannin and iron solution-impregnated cotton showed that the black color of the traditional Bogolan cloth is dominated by the formation of iron-tannin complexes. The presence of iron in the Bogolan cloth was confirmed using XANES data, supporting the notion that iron has been transferred from the iron-rich clay-based mud to the cloth. The chemistry of Bogolan cloth is not only historically and culturally significant and of importance in textile conservation, but may also inspire future research on sustainable dyeing and processing techniques based on natural products.