Alum, More Precious than Gold: The Amazing Influence and Trade of Alum Across the Ages

An exploration of the vital but overlooked role of alum in global trade, dye production, and historical events spanning centuries.

Never heard of alum? You’re not alone.

Yet, for centuries, alum was vital to the production of coloured cloth. Alum was needed to fix dyes and colours to the cloth. Without alum, the colours ran and faded. With alum, they shone and were fast. As a result, as the Italian scientist Vanoccio Biringucci put it in the 16th century, alum was as ‘essential to dyers as br...