Crown glass
Description
1) A hard, clear optical glass made of soda-lime. Crown glass has a low dispersion and a low refractive index.
2) An old form of window glass produced by spinning a globe of glass to form a thin, flat circle. The flattened sheet had a thicker raised center, called a crown or bull's eye, from the glassmaker's pontil. The spun circles had diameters up to 1.2 meters (44 inches). The outer, thin areas were cut into small rectangular, triangular or diamond shapes and mounted in a lead lattice. The glass retains concentric ripple lines from the spinning process. Perhaps originally developed in Syria, crown glass was used in Europe since at least the 14th century. Crown glass made in Normandy region of France was considered to be a high quality glass. It was typically a light blue or green color with a bright fire-polished finish. Because, England had a glass tax for which the inferior center bull's eye was exempt, those portions were often used for inexpensive windows in doors.
Synonyms and Related Terms
2: verre en plats (Fr.); vidro de coroa ou prato (Port.); Normandy glass; bull's eye glass
Resources and Citations
- Bill Bryson, ‘At Home: A Short History of Private Life’ Doubleday Publishers, London 2010.
- G.S.Brady, Materials Handbook, McGraw-Hill Book Co., New York, 1971 Comment: p. 361
- Walter C. McCrone, John Gustave Delly, The Particle Atlas, W. McCrone Associates, Chicago, IV, 1972
- Dictionary of Building Preservation, Ward Bucher, ed., John Wiley & Sons, Inc., New York City, 1996
- G.Allen, L.Black,K.Hallam, "A Preliminary Investigation into the Effect of Self-Adhesive Ultraviolet Absorbing Films on Window Glass" in ICOM preprints Lyon, 1999. p.757-763; EU dictionary
- Encyclopedia Britannica: https://www.britannica.com/technology/crown-glass
- Wikipedia: Crown glass Accessed March 2025