Historical Traditions in the Manufacture of Antique Window Glass
The history of antique window glass goes back to a time just before the turn of the first century AD. Phoenicians along the Syrian-Palestinian coast developed a technique of glassblowing that allowed for a variety of shapes of hollow glass items. Spreading throughout Germany, Italy, France, and Switzerland as a result of the rise of the Roman Empire, glassmaking flourished and the Romans began using it for architectural purposes.
Antique Window Glass: Then and Now
It wasn't until the eleventh century that the mouthblown cylinder technique of making sheet glass for windows was first developed in Germany and later adopted by the Venetians. Cylinder glass and Crown glass are two types of authentic, mouthblown antique window glass typically found in historical structures in the United States. Both types employ a blowpipe to shape the molten glass.
Cylinder glass begins as a ball of molten glass on the end of a blowpipe that is rhythmically blown and swung in a deep pit until an elongated pod-shape forms and a desired length and diameter are reached. Once cooled, the ends of the "pod" are cut from the glass to form a cylinder, which is then scored down its length, reheated and flattened.
Crown glass was originally developed in the 7th - 8th century and later revived for the purposes of window glass making as an alternative to the mouthblown cylinder glass. The process for blowing Crown glass, also called bullion because of its disc-like shape, is slightly different. It begins with a ball of semi-molten glass on the end of a blowpipe that is opened outwards on the opposite side of the pipe, like a Žcrown.' It is then transferred from the blowpipe to a pontil, or "punty" rod, and flattened into a bullion or disc-shape by reheating and spinning. This type of sheet glass has size limitations. Oftentimes, panes had to be joined together with lead strips to create windows.
Although replaced by modern methods developed during the Industrial Revolution, some of these early manufacturing processes for making window glass are still practiced in Europe today to capture the original look and feel of authentic antique window glass - the characteristically "wavy" glass originally installed in fine American homes throughout the seventeenth - early twentieth centuries.
Manufacture of Antique Window Glass After the Industrial Revolution
The Industrial Revolution of Western Europe eventually made its way across the ocean to influence the industrialization of the United States and many of its manufacturing processes. Antique window glass found in many American homes and structures after the beginning of the 20th century was no longer produced by the mouthblown method.
In 1903 the first mechanical method for "drawing" window glass was invented in the United States. Somewhat resembling the mouthblown process for making cylinder glass, large cylinders of glass measuring forty feet in height were drawn vertically from a circular tank and then cut into seven to ten foot cylinders. Just as with the mouthblown method, the drawn cylinder glass was cut lengthwise, reheated and flattened.
Bendheim Restoration Glass®: All the Beauty of Authentic Antique Window Glass Today
Now you can have the old world look and feel you desire, including the characteristic imperfections found in authentic antique window glass, in a special glass product that offers you:
Antique glass look and feel made using the authentic mouthblown cylinder glass techniques as they have been preserved and handed down through generations of Lamberts craftsmen
Custom sizes cut to your specification
Greater ease of handling than salvaged authentic antique glass
Consistency of color, brilliance and body
Easier color matching (authentic antique window glasses can differ slightly in hue, making them very difficult to match)
Available in safety laminated form to meet stringent modern building safety codes and provide sound control benefits
Bendheim Restoration Glass® is the mark of distinction.
Hand Blown Glass: Manufacturing Process: http://www.londoncrownglass.co.uk/Manufacturing.html
A Brief History of Glass: http://www.glassonline.com/infoserv/history.html
Crown Glass: http://en.wikipedia.org/wiki/Crown_glass_(window)
Machine Drawn Cylinder Sheet: http://en.wikipedia.org/wiki/Machine_drawn_cylinder_sheet
McGrath, Raymond and A.C. Frost. Glass in Architecture and Decoration. London, England: The Architectural Press, 1937