Q. How were cylinder glass windows made?

Making Cylinder Glass Windows

Image: Postcard is of photograph of Verreries du Centre de Jumet, in Jumet, Belgium, around 1910. Featured in foreground are three women holding large glass cylinders; the cylinders would then be cut into windows. Several young boys are featured, posing, behind other cylinders while many men are pictured in background, some posing while others are working. 

Here is a short answer of how cylinder glass (also sometimes called broad or sheet glass) was made, from Kenneth M. Wilson's article "Plate Glass in America: A Brief History," in Journal of Glass Studies:

Cylinder glass was made by blowing a large sphere of glass and then elongating it by swinging it, either in a pit or from an elevated platform opposite the furnace. After a cylinder had been formed, it was broken off the blowpipe and, when it had cooled, the ends were removed. The glass was then slit lengthwise, reheated in a special annealing oven, and partly opened by a workman using a wooden block at the end of a stick. The glass collapsed under its own weight into a flat sheet, and it was then smoothed with the wooden block, which created blemishes and irregularities in the finished sheet.

Those looking for a more highly detailed description should read Chapter 3: The Hand Process in Arthur Fowle's book, Flat Glass.

Resources:

Books:

• Asahi Garasu Kabushiki Kaisha. Window Glass. Japan: Asahi Glass Co. Ltd., 1920. 
• Cook, Frank Palmer. Talk to Me of Windows; an Entertaining Story About Windows. [1st American ed.]. South Brunswick: A. S. Barnes, 1971. 
• Corning Museum of Glass. Innovations in Glass. Corning, N.Y: The Corning Museum of Glass, 1999. 10-11.  
• Fowle, Arthur E. Flat Glass. Toledo, Ohio: s.n., 1924. Read Flat Glass now at HathiTrust Digital Library 
• Giblin, James Leonard. Let There Be Light: a Book About Windows, Illustrated with Photographs and Prints /. 1st ed. New York: Crowell, 1988. 
• Wilson, Kenneth M. “Window Glass in America.” In: Building Early America: Contributions toward the History of a Great Industry, edited by Charles E. Peterson, 150-64, 1st ed. Radnor, Pa: Chilton Book Co., 1976.  

Articles: 

• Firth, Mike. “Making Tubes & Sheets of Glass.” Hot Glass Bits (2002). Read “Cylinder Glass - Blowing a bottle for sheet” now at Mike Firth’s website 
• Scientific American. “How Common Window Glass is Made.” Scientific American 20, no. 8 (1869): 114. Read “How Common Window Glass is Made” now at ScientificAmerican.com 

• Wilson, Kenneth M. “Plate Glass in America: A Brief History.” Journal of Glass Studies 43 (2001): 141–53. Read “Plate Glass in America: A Brief History now at JSTOR 

Videos: 

• “Cylinder of Window Glass.” Corning Museum of Glass. 2012. YouTube video, 00:01:49. https://youtu.be/hx2JO1QcZjY  
• Fremont Antique Glass. “Fremont Glass Demo - Antique stain glass windows - Blown glass.” Siuco. 2009. YouTube video, 00:04:19. https://www.youtube.com/watch?v=4_FyF01ua7k 
• Leap, J. Kenneth. “Muff method for making stained glass sheets.” J. Kenneth Leap. 2012. YouTube video, 00:03:07. https://www.youtube.com/watch?v=4_ctsi5_FhI 
• Spillman, Jane Shadel, curator. “Uncut Crown of Glass.” Corning Museum of Glass. 2012. YouTube video, 00:02:22.  https://youtu.be/kzBXU2ovfGo 
• Thompson, Cappy. Cappy Thompson Gathering the Light /. Tacoma, Wash: Museum of Glass, 2003. 
• Verrerie de Saint Just. “Handblown Sheet Glass.” VitreosityInMotion. 2010. YouTube video, 00:06:16. https://www.youtube.com/watch?v=ExyfPl5z2NY 

The Rakow Research Library will lend designated books from its collection and will send copies of articles on request from other libraries. Your local school, public, academic or special library can request items through the OCLC WorldShare Interlibrary Loan (ILL) system or by direct request through email at ill@cmog.org. For more information, please see our ILL website (https://info.cmog.org/library/using-rakow-research-library/interlibrary-loan).