User:TwoScars/sandbox6

From Wikipedia, the free encyclopedia

Glassmaking

Glass is made by starting with a batch of ingredients, melting it, forming the glass product, and gradually cooling it.[1] The batch of ingredients is dominated by sand, which contains silica.[2] Other ingredients such as soda ash, potash, lime, and recycled glass (cullet) are added.[3] Additional ingredients may be added to color the glass. For example, an oxide of cobalt is used to make glass blue.[4] The batch is placed inside a pot or tank that is heated by a furnace. A 2004 description of the Blenko melting process said the batch is heated to about 2600 °F (1427 °C), and cooked for about 24 hours. Then the mixture is cooled to between 2000 °F (1093 °C) and 2300 °F (1260 °C), making it ready to be blown and shaped.[5] Final glass products must be cooled gradually (annealed), or they will break.[6] A conveyor oven called a lehr, hot at the beginning of the conveyor and room-temperature at the end, is used for annealing.[7]

Glassware production

Glassware making at Blenko Glass Company is done using centuries-old processes, with all products handmade. During the 1950s, there were typically ten glassware production teams consisting of six or seven people led by the glassblower.[8] Glassware production begins with a gatherer collecting a "gob" of molten glass from a furnace using a blowpipe.[1] The blowpipe is given to a glassblower who blows into the pipe to shape the glass. The shaping is assisted by the use of tools, and some glass is blown into a mold. In some cases, separate gobs of glass (such as handles) may be added to the main piece. The glass can be reheated in a small furnace called a "glory hole" that makes it easier to modify the glass. Final shaping is done by a finisher who may cut off pieces of glass. The final product is annealed on the lehr. After the glass has cooled on the lehr, the product is inspected, packaged, and shipped.[1]

Flat glass production

Flat glass making at Blenko utilized the hand–blown cylinder glass method that was common in the 1880s.[9] During the first quarter of the 20th century, many other flat glass makers replaced well-paid human glassblowers with the Lubbers glassblowing machine. A few years later, the entire process was changed and became more automated.[10][Note 1] Blenko did not update its method for making flat glass. Its process remained similar to its glassware methodology, but less shaping was needed. After the gatherer retrieved a gob of glass, the glassblower blew a hollow cylinder into a mold. The cylinder was annealed and then cut on both ends. A cut was then made lengthwise on the cylinder and it was placed in a reheating furnace where the cylinder opens and flattens. The glass was then annealed once again.[1]

Blowing the cylinder into a mold is not a normal part of the cylinder method. William J. Blenko received a patent on his process of using an unpolished mold to make the flat glass uniform in size and giving it an appearance that suggests it is old. The patent was called "Art Glass and Method of Making the Same". He filed for the patent on February 26, 1924, and it was granted on May 4, 1926.[13] In the illustration accompanying Blenko's patent, one can see a drawing of the inside of a mold in Figure 1. A gob of molten glass attached to a blowpipe is inserted into the mold in Figure 2. The glassblower blows the gob of glass into cylinder inside the mold, and the mold with the glass cylinder inside can be seen in Figure 3. In Figure 4, the ends of the cylinder have been cut off, and the remains of the cylinder was sliced lengthwise. Figure 5 shows the flat glass after it had been flattened and annealed. Each sheet is uniform in size.[13]

Notes

Related Articles

Wikiwand AI