Glass roots: examining the archaeology of glassmaking in England

Glassmaking, like ceramic production, is one of those skills that went into abeyance in post-Roman Britain. The people of Britain seem to have been supremely competent when working in metal, wood, leather, bone, stone, textile, and even manuscript illumination during the early medieval period, but for glass they went elsewhere. High-status carousers at Tintagel and Cadbury used decorated glassware from south-west France and Spain for their alcohol consumption in the 5th and 6th centuries, while glass of Continental and Mediterranean origin was finding its way to high-status settlement sites as far apart as Devon and Strathclyde. Meanwhile, excavated finds from East Anglia show that this fragile material was reaching the region from the Rhineland. Rare and jewel-like millefiori glass was used as a decorative insert into early medieval metalwork – again possibly imported from the near Continent – and grave goods show that high-ranking women wore necklaces in which glass beads were treated as equivalent to semi-precious stones and jewels.

Though older glass lacks the transparency of modern float glass, the size and shape of the panes, the variation in colour, and the ripples in the glass all add to a building’s personality, as here at King’s Manor, York. ALL images: David Dungworth, unless otherwise stated.

Various excavations have uncovered evidence for insular glassmaking in the 6th to 9th centuries (for example, on Iona and at Whithorn), but when Benedict Biscop set about building his model Roman-style monastery at Wearmouth in AD 673, he had to bring glaziers from Gaul to make glass for the windows, lamps, and vessels used in the church. It is likely that glass salvaged from Roman sites was being recycled here, rather than being manufactured using raw materials. Certainly, this was true at Glastonbury Abbey, where chemical analysis of the glass from late 7th- or early 8th-century furnaces show that it was made from reused Roman glass. Carbon-dated charcoal from the same furnaces suggests that glassworking here was linked to the building of the first stone church by King Ine (AD 688-726) and that, as at Wearmouth, specialist masons and glaziers were brought to Glastonbury from the Continent to build the church and make the windows – indeed, it has been suggested that the same team from Gaul worked at Wearmouth, Glastonbury, and also, perhaps, at York.

OPPOSITE Though older glass lacks the transparency of modern float glass, the size and shape of the panes, the variation in colour, and the ripples in the glass all add to a building’s personality, as here at King’s Manor, York. LEFT Early glass in England is found in medieval buildings especially churches, where small pieces of irregularly shaped coloured glass were painted and held together by lead strips to form pictorial scenes. Most of the glass used in England was imported from the near Continent or made from recycling older glass (including, until the 13th century, ancient Roman glass imported from the Mediterranean). This early 14th-century glass in Christ Church Cathedral, Oxford, depicts St Hild (or Hilda) c.AD 614-680, founder of Whitby Abbey. — Early glass in England is found in medieval buildings especially churches, where small pieces of irregularly shaped coloured glass were painted and held together by lead strips to form pictorial scenes. Most of the glass used in England was imported from the near Continent or made from recycling older glass (including, until the 13th century, ancient Roman glass imported from the Mediterranean). This early 14th-century glass in Christ Church Cathedral, Oxford, depicts St Hild (or Hilda) c.AD 614-680, founder of Whitby Abbey.

The most-common defects in early glass were bubbles and ‘stones’ usually in the form of sand particles that had not melted fully or, as here, fragments of crucible or furnace roof that dropped into the molten glass during firing. This example, from a furnace site at Glasshouse Lane, Kirdford, West Sussex, had been pulled out of the molten glass by the glass-blower using tongs and thrown on a waste pile.

Leaping forward to the 14th century, where David Dungworth’s book on glassmaking in England begins (see ‘Further reading’ on p.27), the archaeological and historical evidence shows that domestic manufacture was now well-established in the Weald of Sussex, Surrey, and Kent, as well as on Cannock Chase in Staffordshire, and probably started in the previous century (an early 13th-century deed grants 20 acres of land near Chiddingfold, Surrey, the site of a later glassworks, to Laurence Vitrearius, a name derived from the Latin vitrum, glass). Crucially, the Weald and the Chase were both home to the extensive tracts of managed woodland that was needed as fuel to form molten glass. This required heating a mixture of silica (often in the form of river sand), a flux (to lower the melting point), stabilising elements (to stop it from tarnishing), and metal oxides (to provide colour) to temperatures of 1,100-1,400°C.

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