Editing Glassblowing (section)

===Modern glassblowing===
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[[File:Goose 8 bg 112303.jpg|thumb|Use of a glory hole to reheat a piece on the end of a blowpipe]]
[[File:Kosta-Boda vinglas, 2018.webm|thumb|thumbtime=5.0|How a wine glass is made, [[Kosta Boda]], video]]
[[File:Mona Morales-Schildt på Kosta Bruk SLSA 1150 foto 2988.jpg|thumb|[[Mona Morales-Schildt]] at Kosta glassworks (Göran Schildt photo)]]
[[File:Cane Foglio - David Patchen.jpg|thumb|Glass can be made with precise striped patterns through a process called [[caneworking|cane]] which involves the use of rods of colored glass]]

The transformation of raw materials into glass takes place at around {{convert|2400|°F|°C|abbr=on|order=flip}};<ref>{{Cite book|url=https://books.google.com/books?id=4NJBAQAAMAAJ&q=glass+at+2%2C400+%C2%BAF+white+hot&pg=PA17|title=Purchasing Agent: Magazine of Centralized Buying|date=1919-01-01|publisher=Purchasing agent Company|language=en}}</ref> the glass emits enough heat to appear almost white hot. The glass is then left to "fine out" (allowing the [[liquid bubble|bubbles]] to rise out of the mass), and then the working temperature is reduced in the furnace to around {{convert|2000|°F|°C|abbr=on|order=flip}}. At this stage, the glass appears to be a bright orange color. Though most glassblowing is done between {{convert|1600|and|1900|°F|°C|order=flip}}, "soda-lime" glass remains somewhat plastic and workable at as low as {{convert|1350|°F|°C|abbr=on|order=flip}}. Annealing is usually done between {{convert|700|and|900|°F|°C|order=flip}}.

{{anchor|glory hole|lehr|annealer}}
Glassblowing involves three [[Industrial furnace|furnace]]s. The first, which contains a [[crucible]] of molten glass, is simply referred to as "the furnace". The second is called the "glory hole", and is used to reheat a piece in between steps of working with it. The final furnace is called the "lehr" or "annealer", and is used to slowly cool the glass, over a period of a few hours to a few days, depending on the size of the pieces. This keeps the glass from cracking or shattering due to [[thermal stress]]. Historically, all three furnaces were contained in one structure, with a set of progressively cooler chambers for each of the three purposes.