Last edited 06 Mar 2021

Glass blowing

Stained Glass Windows: Managing Environmental Deterioration, published by Historic England in 2020, suggests that glass blowing is a: ‘Glass-forming technique, probably developed in Babylonia and the Middle East by the 1st century BC. Molten glass is gathered into a ball on the end of a hollow pipe, and rolled on an iron former to roughly shape it and to slightly cool the surface. Then the pipe is used to blow air into the glass and form it into a bubble. By repeated blowing, shaping and reheating, the glass can be formed in many ways.’

Archaeological Evidence for Glassworking, Guidelines for Recovering, Analysing and Interpreting Evidence, published by Historic England in 2018, defines a blowing iron as: ‘A long iron tube that was dipped into the molten glass to collect a gather for subsequent inflating and shaping.’

It defines optic blowing as a process in which: 'A gather of glass is blown into a mould with a pattern on the inner surface, which transfers to the glass. Continued free blowing results in movement and distortion of the pattern.'

And overblow as: 'A by-product of mould blowing, referring to the glass that remains outside the mould, which is removed and recycled.'

It defines paraison as: 'The partially inflated gather of glass at the end of the blowing iron.'

And paraison end as: 'A marble-shaped blob of glass pinched from the end of the gather during the blowing of particular forms, such as the bowls of goblets.'

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