英语论文网

ng pipe would keep the glass symmetrical and round as it expanded. More and more layers of liquid glass are added, and the final shaping touches are applied with tools to create a base and lip for the vessel. After it gets cooler, the piece is carefully broken off the pipe and set down to finish hardening (Stern, 20-34).

A further advancement by the Romans was a technique called mold-forming or kiln-forming. This is achieved by placing the pipe inside of a pre-made mold, and blowing the molten glass gob inside of it until it fills it up and presses against the insides of the mold. After the mold has been filled up by the glass, the glass blower's assistant(s) remove pieces of the mold from around the pipe. The pipe was held vertically so that gravity would not cause the molten glass to become asymmetrical. Then it is removed and further shaped (Stern, 45). Kiln-forming allowed for more intricate and advanced vessels. Even so, not everything was perfect with these vessels. When cups, vases, and other containers were made, the lips were usually lightly grounded had a slightly sandpapery texture, rather than the smooth, sleek texture most people today enjoy. The reason the Romans had these issues was because when the glass was gently broken off of the pipe, the edges of the lip would be sharp (Cummings, 47). The edges would be ground up until the sharp edges were gone, leaving a symmetrical but slightly different-textured finish (Stern, 45). Folded rims were the solution to this issue. Roman glass blowers would, instead of waiting for the rims to cool for grinding, reheat the neck of the vessel and manipulate it in such a way that the rim collapsed inward to form a lip folded outward, upward, and inward. All of this was skillfully done without even touching the glass - merely using heat and gravity; the glass blower could achieve this effect (Stern, 45).

Because of the ease of production brought on by glassblowing, many glass artisans feared loss of prestige and societal standing due to the possibility of mass production. In response, they developed new and inventive processes fusing formative and decorative shapes into some of the most prized pieces of luxury glassware that have ever existed (Cummings, 174). Stained glass, sheet glass, and mosaic glass were all the products of artisans experimenting with developing new techniques.

The invention of sheet glass by the Romans in the first century CE was the earmark of using glass for windows in a building. Sheet glass is creating by blowing glass on a pipe, like normal, but the glass bubble would be raised up and spun as if spinning a lasso and the gravitational pull would flatten the glass out in a sheet a few meters in diameter, depending on the purpose it was being made for. The sheets were trimmed into rectangles and fused together with lead strips, effectively forming a window grid. This glass wasn't perfectly flat, of course, nor was it perfectly transparent. The windows made from these sheets of glass were cloudy, but they still served the purpose of letting light in and keeping the elements out. These windows, at first, were only installed in the homes of the wealthy, upscale churches, and government buildings (Cummings, 175). Even then, more efficient methods of production were discovered for producing sheet glass and most people eventually had glass windows installed in their homes and businesses. Glassmaking artisans then went on to produce e本论文由英语论文网提供整理，提供论文代写，英语论文代写，代写论文，代写英语论文，代写留学生论文，代写英文论文，留学生论文代写相关核心关键词搜索。