Open main menu
Home
Random
Recent changes
Special pages
Community portal
Preferences
About Wikipedia
Disclaimers
Incubator escapee wiki
Search
User menu
Talk
Dark mode
Contributions
Create account
Log in
Editing
Glassblowing
(section)
Warning:
You are not logged in. Your IP address will be publicly visible if you make any edits. If you
log in
or
create an account
, your edits will be attributed to your username, along with other benefits.
Anti-spam check. Do
not
fill this in!
===Principles=== [[File:bristol blue glass manufacture arp.jpg|thumb|A stage in the manufacture of a [[Bristol blue glass]] ship's [[decanter]]. The blowpipe is being held in the glassblower's left hand. The glass is glowing yellow.]] As a novel glass forming technique created in the middle of the 1st century BC, glassblowing exploited a working property of glass that was previously unknown to glassworkers; inflation, which is the expansion of a molten blob of glass by introducing a small amount of air into it. That is based on the liquid structure of glass where the atoms are held together by strong chemical bonds in a disordered and random network,<ref name="Frank">Frank, S 1982. Glass and Archaeology. Academic Press: London. {{ISBN|0-12-265620-2}}</ref><ref name="Freestone">Freestone, I. (1991). "Looking into Glass". In S. Bowman (ed.) ''Science and the Past''. pp.37β56. University of Toronto Press: Toronto & Buffalo. {{ISBN|0-7141-2071-5}}</ref><ref name="Pollard">Pollard, A.M. and C. Heron 2008. [https://books.google.com/books?id=CT_FWEfanCIC Archaeological Chemistry]. The Royal Society of Chemistry {{ISBN|0-85404-262-8}}</ref> therefore molten glass is viscous enough to be blown and gradually hardens as it loses heat.<ref name="Cummings">Cummings, K. 2002. [https://books.google.com/books?id=nm387Ui_DEAC A History of Glassforming]. University of Pennsylvania Press {{ISBN|0812236475}}</ref> To increase the stiffness of the molten glass, which in turn makes the process of blowing easier, there was a subtle change in the composition of glass. With reference to their studies of the ancient glass assemblages from [[Sepphoris]]. postulated that the concentration of [[natron]], which acts as [[Flux (metallurgy)|flux]] in glass, is slightly lower in blown vessels than those manufactured by casting. Lower concentration of natron would have allowed the glass to be stiffer for blowing. During blowing, thinner layers of glass cool faster than thicker ones and become more viscous than the thicker layers. That allows production of blown glass with uniform thickness instead of causing blow-through of the thinned layers. A full range of glassblowing techniques was developed within decades of its invention.{{Citation needed|date=March 2013}} The two major methods of glassblowing are free-blowing and mold-blowing. ====Free-blowing==== [[File:Brooklyn Glass (32606)a.jpg|alt=Glassworking in a hot shop in New York City|thumb|Glassworking in a hot shop in New York City]] This method held a pre-eminent position in glassforming ever since its introduction in the middle of the 1st century BC until the late 19th century, and is still widely used as a glassforming technique, especially for artistic purposes. The process of free-blowing involves the blowing of short puffs of air into a molten portion of glass called a "gather" which has been spooled at one end of the blowpipe. This has the effect of forming an elastic skin on the interior of the glass blob that matches the exterior skin caused by the removal of heat from the furnace. The glassworker can then quickly inflate the molten glass to a coherent blob and work it into a desired shape.<ref name="Cummings"/><ref name="Mariacher">{{cite book|last1=Mariacher|first1=G|title=Glass: from Antiquity to the Renaissance|isbn=0600012506|date=1970|publisher=The Hamlyn Publishing Group Limited|location=Middlesex|url-access=registration|url=https://archive.org/details/gothicilluminate00coen}} (apparently out of print)</ref><ref name="Zerwick">{{cite book|author1=Chloe Zerwick|author2=Corning Museum of Glass|title=A short history of glass|url=https://books.google.com/books?id=G1ZQAAAAMAAJ|date=May 1990|publisher=H.N. Abrams in association with the Corning Museum of Glass|isbn=9780810938014}}</ref> Researchers at the [[Toledo Museum of Art]] attempted to reconstruct the ancient free-blowing technique by using clay blowpipes. The result proved that short clay blowpipes of about {{convert|30|β|60|cm|abbr=on}} facilitate free-blowing because they are simple to handle and to manipulate and can be re-used several times.<ref name="Stern">{{cite book|author1=Birgit Schlick-Nolte|author2=E. Marianne|title=Early glass of the ancient world: 1600 B.C.-A.D. 50 : Ernesto Wolf collection|url=https://books.google.com/books?id=dJUsAQAAIAAJ&q=clay+blowpipe|year=1994|publisher=[[Gerd Hatje|Verlag Gerd Hatje]]|isbn=978-3-7757-0502-8|pages=81β83}}</ref> Skilled workers are capable of shaping almost any vessel forms by rotating the pipe, swinging it and controlling the temperature of the piece while they blow. They can produce a great variety of glass objects, ranging from drinking cups to window glass. An outstanding example of the free-blowing technique is the [[Portland Vase]], which is a cameo manufactured during the Roman period. An experiment was carried out by Gudenrath and Whitehouse<ref name="Gudnerath">{{cite journal |last1=Gudenrath |first1=W. |last2=Whitehouse |first2=D. |year=1990 |title= The Manufacture of the Vase of its Ancient Repair |journal=Journal of Glass Studies |volume= 32 |pages= 108β121 |jstor=24188035}}</ref> with the aim of re-creating the Portland Vase. A full amount of blue glass required for the body of the vase was gathered on the end of the blowpipe and was subsequently dipped into a pot of hot white glass. Inflation occurred when the glassworker blew the molten glass into a sphere which was then stretched or elongated into a vase with a layer of white glass overlying the blue body. ====Mold-blowing==== [[File:Bamboo Framing.jpg|thumb|left|upright|Glassblower [[Jean-Pierre Canlis]] sculpting a section of his piece "Insignificance"]] Mold-blowing was an alternative glassblowing method that came after the invention of free-blowing, during the first part of the second quarter of the 1st century AD.<ref name="Lightfoot">{{cite journal|author=Lightfoot, C.S.|year= 1987|title= A Group of early Roman Mould-Blown Flasks from the West|journal= Journal of Glass Studies |volume=29|pages= 11β18}}</ref><ref name="Pricea">Price, J. (1991). "Decorated Mould-Blown Glass Tablewares in the First century AD". In M. Newby & K. Painter (eds.) ''Roman Glass: Two Centuries of Art and Invention''. pp. 56β75. The Society of Antiquaries of London: London {{ISBN|0-85431-255-2}}</ref> A glob of molten glass is placed on the end of the blowpipe, and is then inflated into a wooden or metal carved mold. In that way, the shape and the texture of the bubble of glass is determined by the design on the interior of the mold rather than the skill of the glassworker.<ref name="Cummings"/> Two types of mold, namely single-piece molds and multi-piece molds, are frequently used to produce mold-blown vessels. The former allows the finished glass object to be removed in one movement by pulling it upwards from the single-piece mold and is largely employed to produce tableware and utilitarian vessels for storage and transportation.<ref name="Tattona">Tatton-Brown, V. (1991). "The Roman Empire". In H. Tait (ed.) ''Five Thousand Years of Glass''. pp. 62β97. British Museum Press: London {{ISBN|0-8122-1888-4}}</ref> Whereas the latter is made in multi-paneled mold segments that join together, thus permitting the development of more sophisticated surface modeling, texture and design. The Roman leaf beaker which is now on display in the J. Paul Getty Museum was blown in a three-part mold decorated with the foliage relief frieze of four vertical plants.<ref name="Wright">{{cite journal|author=Wright, K.|year= 2000|title= Leaf Beakers and Roman Mould-blown Glass Production in the First Century AD|journal=Journal of Glass Studies |volume=42|pages= 61β82}}</ref> Meanwhile, Taylor and Hill<ref name="Taylor">Taylor, M. & D. Hill 1998. Making Roman Glass Today. In The Colchester Archaeologist 11</ref> tried to reproduce mold-blown vessels by using three-part molds made of different materials. The result suggested that metal molds, in particular bronze, are more effective in producing high-relief design on glass than plaster or wooden molds. The development of the mold-blowing technique has enabled the speedy production of glass objects in large quantity, thus encouraging the mass production and widespread distribution of glass objects.<ref name="Pricea"/><ref name="Cuneaz">Cuneaz, G. (2003). "Introduction". In R.B. Mentasti, R. Mollo, P. Framarin, M. Sciaccaluga & A. Geotti (eds.) ''Glass Through Time: history and technique of glassmaking from the ancient world to the present''. pp. 11β30. Skira Editore: Milan {{ISBN|978-88-8491-345-6}}</ref>
Edit summary
(Briefly describe your changes)
By publishing changes, you agree to the
Terms of Use
, and you irrevocably agree to release your contribution under the
CC BY-SA 4.0 License
and the
GFDL
. You agree that a hyperlink or URL is sufficient attribution under the Creative Commons license.
Cancel
Editing help
(opens in new window)