Part III, ‘The Workshop’, unpacks the cultural significance of the mineral alum, which was imported in bulk, as an essential mordant for the cloth industry. Chapter 5 revives the origin narrative of the essential mineral as the product of the Dead Sea – which itself was seen as the ashes of the destroyed cities of Sodom and Gomorrah. Sturmy’s ship contained 152 tons of alum, an amount which would have dyed 34,000 cloths, equivalent to the total number of cloths exported from England in a year in the 1450s. Sturmy’s intent accordingly appears to have been to monopolise the English supply of alum: this object assumes crucial significance as a motivating factor for his venture. Alum both extends and deviates from the themes of this study. Instead of the rare, luxurious and sweet objects seen hitherto, alum was bought in bulk, industrial and noxious. Alum was a widespread presence in medieval English imaginations and culture, overlaid with a narrative of Dead Sea origins which caused it to be received as Sodomite salt – the Dead Sea said to have been formed from the destroyed cities of Sodom and Gomorrah. These Sodomite origins continued to inflect the use of alum in dye-making, surgery, bookmaking, and alchemy.