Glassblowing

• 1. Origins And Invention

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  In the middle of the 1st century BC, Phoenician and Syrian craftsmen developed a technique that changed history. They blew air into molten glass to create bubbles. This method exploited inflation, an unknown property at the time. The liquid structure of glass allowed atoms to hold together in a disordered network. Molten glass became viscous enough to be blown while gradually hardening as it lost heat. Researchers studying ancient glass assemblages from Sepphoris found subtle changes in composition. The concentration of natron acted as flux but was slightly lower in blown vessels than cast ones. Lower natron levels made the glass stiffer for blowing. Such inventions swiftly eclipsed all other traditional methods like casting or core-forming.

• 2. Technical Principles

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  A stage in the manufacture of a Bristol blue glass ship's decenter shows the blowpipe held in the left hand. The glass glows yellow inside the furnace. Thinner layers of glass cool faster than thicker ones during the process. These thinner layers become more viscous than the thicker sections. That allows production of blown glass with uniform thickness instead of causing blow-through. A full range of techniques developed within decades of its invention. Free-blowing held a pre-eminent position until the late 19th century. It remains widely used today especially for artistic purposes. The process involves blowing short puffs of air into a molten portion called a gather. This forms an elastic skin on the interior matching the exterior skin caused by cooling.

• 3. Methodologies And Tools

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  Glassworking in a hot shop in New York City demonstrates modern free-blowing practices. Researchers at the Toledo Museum of Art reconstructed ancient techniques using clay blowpipes. Short clay blowpipes about three feet long facilitate free-blowing because they are simple to handle. Skilled workers shape almost any vessel form by rotating the pipe and swinging it. They control temperature while blowing to produce drinking cups or window glass. An outstanding example is the Portland Vase manufactured during the Roman period. Gudenrath and Whitehouse re-created this vase by gathering blue glass then dipping it into white glass. Inflation occurred when the worker blew the molten glass into a sphere stretched into a vase. Mold-blowing emerged as an alternative method during the first part of the second quarter of the 1st century AD.

• 4. Roman Expansion

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  The invention of glassblowing coincided with the establishment of the Roman Empire in the 1st century BC. Blown glass has been found in many areas of the Roman world. On eastern borders, Phoenicians set up large workshops in contemporary Lebanon and Israel. Ennion was among the most prominent glassworkers from Lebanon of that time. He produced multi-paneled mold-blown vessels complex in shapes and decorative motifs. The technique reached Egypt and appeared in a fragmentary poem printed on papyrus dated to the 3rd century AD. Later craftsmen advanced to northern Europe building workshops in Switzerland and France. One prolific center established Cologne on the river Rhine by the late 1st century BC. Stone base molds and terracotta base molds were discovered from these Rhineland workshops. Remains of blown blue-green glass bottles and indented beakers were found at Poetovio and Celeia in Slovenia.

• 5. Medieval And Renaissance Revival

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  The glass blowing tradition continued through the Middle Ages until the demise of the Roman Empire in the 5th century AD. During the early medieval period, Franks manipulated the technique creating simple corrugated molds. They developed claw decoration techniques for drinking vessels imitating animal horns. These objects were produced in the Rhine and Meuse valleys as well as Belgium. Byzantine glassworkers made mold-blown glass decorated with Christian and Jewish symbols in Jerusalem between the late 6th century and middle of the 7th century AD. Mold-blown vessels with facets and relief decoration were discovered at Samarra in Islamic lands. Renaissance Italy witnessed revitalization of the industry when Venetian workers from Murano produced fine cristallo glassware. The technique combined with cylinder methods manufactured sheet or flat glass for window panes in the late 17th century. Glass was being blown in many parts including China Japan and Islamic Lands.

• 6. Modern Studio Movement

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  The studio glass movement began in 1962 when Harvey Littleton and Dominick Labino held workshops at Toledo Museum of Art. Littleton was a ceramics professor while Labino served as chemist and engineer. They experimented with melting glass in small furnaces to create blown art. Littleton promoted use of small furnaces in individual artists' studios. This approach blossomed into worldwide movement producing flamboyant artists like Dale Chihuly and Dante Marioni. Today institutions offer resources for training and sharing equipment globally. Working with large pieces requires team choreography of precisely timed movements. Recent technology allows use of glass components in high-tech applications. Machineries shape and form products of highest quality for semiconductor medical and industrial uses. Lampworkers manipulate preformed rods using oxygen propane flames to create laboratory glassware.