Medieval and post-medieval glass technology: Bracken as a sustainable resource for glassmaking

The growth behaviour of bracken, which was sampled throughout the spring, summer and early autumn of 1999 from two different sites, is used to establish whether bracken was a sustainable supply of alkali for use by medieval and early post-medieval glassmakers. Data from the collection of bracken from the Snake Pass, Derbyshire and from Cannock Chase near Rugeley, Staffordshire is presented. The field evidence suggests that bracken could have played such a role, being used as a single alkali added to the glass batch for specialist glasses or to complement other alkali raw materials.