English Medieval glass-making technology : scientific analysis of the evidence

• Main Author: Merchant, Ian James
• Published: University of Sheffield 1999
• Subjects: 930.1
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.287681

This scientific analysis of evidence excavated from glass-making sites, Blunden's Wood (c. 1330 AD), Knightons (c. 1550 AD) and Sidney Wood (1600 - 1620 AD), has provided further understanding of the technology used to produce `forest' glass in England between the fourteenth and seventeenth centuries. The influx of immigrant glass-makers into England during this time, especially during the sixteenth century, had a large impact on the English glass industry. The production of `forest' glass used ash and sand as the raw ingredients in the glass batch. This work demonstrated that it was possible to determine the correlation between certain components in the glass, and therefore, determine which components entered the batch from the sand, and those that entered from the ash. This work hinted that oak ash was used in preference to beech. In addition to this, it appeared that fritting did take place, from the evidence from Blunden's Wood, at a temperature in the region of 900 °C. This frit was then melted at a temperature that may have been as high as 1300 °C. The changes in glass technology began to take place during the middle of the sixteenth century, and in the first quarter of the seventeenth century the `forest' glass industry ceased. The move to coal-fired furnaces, the higher demand for glass and the improvement in quality of glass all contributed to the expansion and migration of the industry that was seen at the start of the seventeenth century.