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Posted on October 24, 2007 by Jason Petrina | Posted under Reference and Education
The History of Mirrors
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The ancient Egyptians, Romans and Greeks were quite fond of mirrors and often produced small hand mirrors from sheets of highly polished copper and bronze. A handle would be attached so that one could easily use the mirror for self-viewing. Glass mirrors came about during the third century A.D. and were quite common in Egypt, Gaul, Germany and Asia Minor. Generally, the earliest known glass mirrors were only about three inches in diameter and many people still preferred to use mirrors manufactured from metal due to the fact that glass mirrors still not have a very good reflection. They became more popular as a method was discovered which allowed artisans to produce flat thin glass and spread hot metal onto the glass without breaking it. By the twelfth century, glass mirrors were coming into more usage in Germany and Italy and eventually spread to England. The discovery of glassblowing during the 14th century led to the invention of convex mirrors, which did much to increase the popularity of glass mirrors. Until this time all mirrors had been flat or plane mirrors. The production of a convex mirror allowed a reflection to appear larger in the center. About the same time, people became experimenting with the production of mirrors from liquid metals. One of those experiments involved an amalgam of tin and mercury, leading to the development of mercury mirrors. In Venice, during the 16th century, artisans refined the production of glass mirrors and developed a method that would allow them to back a plate of flat glass with a sheet of thin reflecting metal. Glass cylinders were leveled out to produce flat mirrors. Artisans could then cover the reverse side of the mirror with a mixture of tin and mercury. The process was slow and painstaking, requiring artisans to carefully mold and cut the mirror then attach the backing before the metals hardened. Overall, the entire process to create one mirror took more than a month to complete. This type of mirror production was also known to be dangerous and unhealthy due to the fact that exposure to the mercury fumes was known to be toxic. As a result, such mirrors were quite expensive and only the very wealthy could afford them. The process of producing mirrors underwent another drastic change during the 19th century at which time it was discovered that a glass surface could be coated with metallic silver. This discovery seemed to galvanize the mirror production industry, which until this time had been primarily reserved to a few small portions of the world. Just after the turn of the 20th century, in 1903, a method that allowed the production of a two-way mirror, or transparent mirror was discovered by a Russian immigrant living in the United States. Transparent mirrors are produced in a way quite similar to regular mirrors; however, the mirror becomes transparent when strong light is flashed at the back of the mirror. Today, modern mirrors are produced by applying a thin layer of molten silver or aluminum onto the back of a section of glass. Depending on the purpose of the mirror, the aluminum may be evaporated onto the front surface of glass. This method is commonly used in the production of mirrors to be used in telescopes in order to eliminate even faint reflections from the glass. About The Author: Jason Petrina is the Editor and Publisher of Article Click. For more FREE articles for your ezine and websites visit - www.articleclick.com |
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