History of Mirrors - Part 1

• published: 06 Nov 2014
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What we know today as the modern mirror, in which we can see a crystal clear reflection of ourselves, did not come into being just overnight. The primitive mirror, the first mirror used by people were most likely pools of dark, still water, or water collected in a primitive vessel of some sort. The development of mirror started in the ancient world around 6000 BC, when the earliest manufactured mirrors were made out of pieces of polished stones, such as obsidian, a naturally-occurring volcanic glass. Examples of obsidian mirrors were found in Anatolia or modern-day Turkey. These mirrors had a round and slightly convex reflective surface. Their diameters were approximately 9 centimetres, and they form reasonable images. Indeed, for a polished piece of rock, this mirror gives a remarkably clear reflection! Fast forward by almost 3000 years, metal mirrors were invented starting with mirrors of polished copper alloy (especially bronze), which were crafted in Mesopotamia and ancient Egypt. These mirrors allowed correction of some refractive errors present in their predecessors. The early versions were nearly flat; later mirrors were rather convex, which created an upright image in a smaller mirror surface area, thus requiring less bronze. Concave mirrors used to magnify objects were also manufactured. From 2000 BC onwards, mirrors were also made from other metal alloys, such as silver alloy and gold alloy, as well as electrum (a naturally-occurring alloy of gold and silver). Studies into the advanced application of curved mirrors only began in earnest during the period of classical antiquity, in particular by the great classical scholars, Diocles and Ptolemy, who lived between 240 BC and 168 AD. Parabolic (or concave) mirrors were described and studied by the mathematician Diocles in his work On Burning Mirrors, while Ptolemy conducted a number of experiments with curved polished iron mirrors, and discussed plane, convex and concave spherical mirrors in his work Optics. Up to this point in history, we can see that ancient mirrors were useful for basic grooming purposes as they provided a reasonably accurate reflection of self. However, the reflected image was not precise, due to the colour and uneven texture of the surface. The variability of these factors also meant that the reflected images would not have a high degree of consistency. Furthermore, it was rather bulky and inconvenient to carry around these mirrors. The development of curved mirrors was also limited to the experimental stage, without much practical application. The only exception was that convex mirror helped to cut the amount of bronze used to manufacture mirror. Now turning up to the modern era, metal-coated glass mirrors (similar to the modern mirror that we use today) are said to have been invented in Sidon (or modern-day Lebanon) in the first century AD. Glass mirrors backed with gold leaf are mentioned by the Roman author Pliny in his work Natural History, written in about 77 AD. The Romans also developed a technique for creating crude mirrors by coating blown glass with molten lead. By the 11th century, glass mirrors with clarity that is on par with today’s mirrors were being produced in Moorish Spain. However, the technological development surrounding mirrors did not stop there, as manufacturers sought better methods in making mirrors. Some time in the early Renaissance, European manufacturers perfected a superior method of coating glass with a tin-mercury amalgam. The exact date and location of the discovery is unknown, but in the 16th century, Venice, a city famed for its glass-making expertise, became a centre of mirror production using this very technique. Nonetheless, glass mirrors from this period were still an extremely expensive luxury. The invention of the silvered-glass mirror is credited to German chemist Justus von Liebig in 1835. His process involved the deposition of a thin layer of metallic silver onto glass through the chemical reduction of silver nitrate. This silvering process was adapted for mass manufacturing and led to the greater availability of affordable mirrors.