Early modern glass in England
[1] The organisation of production evolved from the small-scale family-run glass houses typical of forest glass-making to large monopolies granted by the Crown.
[4] In the early modern era, network formers were obtained from fine or coarse sands which were usually located near the area of production or from silica based pebbles.
[8][13][14] The groups include: The following table represents the mean compositional data derived from the analysis of materials at the Old Broad Street furnace in London, dated to the early 17th century.
[13] and those recovered from Phase Two (circa 1680-1700 AD) Silkstone, Yorkshire[8][14] This information was gathered from Dungworth's compilation and analysis[8] The data is represented in wt% oxides and those below the detection limits (0.2% or less) are shown by '-'.
These include contaminants in raw materials, furnace conditions, and deliberate additives that would provide known colour variations.
Medieval glasshouse traditions continued in the Weald, which was becoming deforested by the early 17th century; local glassmaking spread elsewhere, where timber was available to fire furnaces, to Hampshire, Gloucestershire, North Staffordshire and the Scottish Borders.
Cullet heaps of broken glass residue were found on either side, suggesting the use of a flux to reduce melting temperatures.
This patent was awarded to Carré on the condition that prices remained low and that glassmaking and blowing would be taught to native Englishmen to promote the craft.
[5] He brought many Venetian craftsmen to his London workshop and opened a second furnace outside the city to produce vessel and green glass.
[2][5][6] This effectively helped to lower the price of clear glassware and made it available to a wider range of the gentry and middle class.
[3] Wing-like additions were added to the late 16th–early 17th century furnace remains at two glass producing sites, Hutton and Rosedale in York, as well as at Vann Copse in the Weald.
[16] A smaller nearby furnace was abandoned around the same time as the addition of the wings, suggesting that they provided an area for either annealing or pre-heating pots.
[5] Rosedale and Vann Copse were constructed in similar styles but with four wings, one in each corner, which were built integral to the original furnace.
[2][11] At this time, a large number of high temperature industries were dependent on wood for fuel, and this began to diminish the country's forests.
[3] Additionally, the carbon from the coal fumes contaminated the glass in the uncovered pots which created a dark and often uneven colour.
[2][6] He began many ventures and set up a successful glasshouse near a coal source in the attempts to save money and to more easily meet the demands of London.
[2][13] Some of his earlier attempts to set up new a furnace to produce glass for the growing needs of London failed, as transportation costs proved to be too high.
[18] Unlike other wing furnaces, the one at this site had deep flues and a centrally located hearth, illustrating the adaptation to a new fuel source.
[6][11][19] Later batches had the addition of lead oxide (PbO) which combatted this problem and produced a superior glass that was more suitable for to engraving and etching.
[5][6][10] The archaeological remains of the Albion shipwreck off Margate in 1765 contained 11 lead glass ingots, which are thought to be meant for trade with China.
[7][11] Additionally, continuous melting production with tank furnaces helped mark the end of the early modern period and the beginning of the Industrial Revolution.
