One of our local volunteers has written an article to give you an introduction to Alum. Come and see some real alum at the museum - and a unique urine barrel... Alum was used as a mordant or fixative for dyes in the textile industry, for waterproofing leather, in the manufacture of parchment, glass and candles, and as a fire-retardant. As a fixative for natural dyes it was essential to allow the finery of the Church, the crown or the court to be distinctive from the drab colo