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Glass is made by starting with a batch of ingredients, melting it, forming the glass product, and gradually cooling it. The batch of ingredients is dominated by sand, which contains silica.[1] Other ingredients such as soda ash, potash, lime, and recycled glass (cullet) are added.[2] Additional ingredients may be added to color the glass. For example, an oxide of cobalt is used to make glass blue.[3] The batch is placed inside a pot or tank that is heated by a furnace roughly to temperatures that range from 2100 °F (1149 °C) to 3090 °F (1700 °C).[4][Note 1] The molten glass is typically shaped into the glass product (other than window glass) by glassblowing or pressing it into a mold.[6] Window glass production during the last half of the 19th century, using a process known as the cylinder method, involved blowing a cylinder and flattening it.[7][Note 2] Glass products must be cooled gradually (annealed), or they will break.[9] An conveyer oven called a lehr, hot at the beginning and room-temperature at the end, is used for annealing.[10]
A major expense for glass factories is fuel for the furnace.[11] In the United States, gas and oil began replacing coal as a fuel for glassmaking in the 1870s—where it was available.[12] Transportation resources are also important for the glass industry. Waterways provide an efficient and safe way to transport glass, especially before the construction of high-quality roads and the railroad system.[Note 3] As the American railroad industry developed, it also became an important transportation resource. The first commercial segment of track in the United States was 13 miles (21 km) long, and it opened in 1830.[14] By 1920, there were over 252,000 miles of railroad line operating in the United States.[15]
- ^ "How Glass is Made – What is glass made of? The wonders of glass all come down to melting sand". Corning. Archived from the original on July 5, 2023. Retrieved July 5, 2023.
- ^ Skrabec 2007, p. 25; Shotwell 2002, pp. 114–115
- ^ Shotwell 2002, p. 94
- ^ "Care and Feeding of the Glass Furnace". Museum of Glass (Tacoma, Washington). Retrieved October 15, 2024.; "How Glass is Made – What is glass made of? The wonders of glass all come down to melting sand". Corning. Archived from the original on July 5, 2023. Retrieved July 5, 2023.
- ^ "A Family Name in Glass". Olney Enterprise (Newspaper Archive). March 18, 2004. p. 22.
The mixture is then placed into an oven, heated....
- ^ Weeks & United States Census Office 1884, p. 45
- ^ Weeks & United States Census Office 1884, p. 20
- ^ "Syrup Off the Roller: The Libbey-Owens-Ford Company". University of Toledo Library. Archived from the original on December 7, 2022. Retrieved March 7, 2024.
- ^ Shotwell 2002, p. 17
- ^ "Corning Museum of Glass – Lehr". Corning Museum of Glass. Archived from the original on July 5, 2023. Retrieved July 5, 2023.
- ^ United States Department of Commerce, Bureau of Foreign and Domestic Commerce 1917, p. 12
- ^ Skrabec 2007, p. 26
- ^ Unknown 1912, p. 25
- ^ "Today in History - February 28 - The B & O Railroad". U.S. Library of Congress. Archived from the original on February 19, 2024. Retrieved February 19, 2024.
- ^ United States Interstate Commerce Commission Bureau of Accounts 1966, p. 50
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