Editing Mirror (section)

===Middle Ages and Renaissance===
[[File:Johann Jacob Kirstein 001.JPG|thumb|An 18th century [[vermeil]] mirror in the [[Musée des Arts décoratifs, Strasbourg]]]]
[[File:Mirror with laquered back inlaid with 4 phoenixes holding ribbons in their mouths. Tang Dynasty. Eastern Xi'an city.jpg|thumb|A mirror with lacquered back inlaid with four phoenixes holding ribbons in their mouths during the [[Tang dynasty]] in eastern [[Xi'an]]]]
The evolution of glass mirrors in the [[Middle Ages]] followed improvements in [[glassmaking]] technology. Glassmakers in [[France]] made flat glass plates by blowing glass bubbles, spinning them rapidly to flatten them, and cutting rectangles out of them. A better method, developed in [[Germany]] and perfected in [[Venice]] by the 16th century, was to blow a cylinder of glass, cut off the ends, slice it along its length, and unroll it onto a flat hot plate.<ref name=bonn2011/>{{rp|p.11}} Venetian glassmakers also adopted [[lead glass]] for mirrors, because of its crystal-clarity and its easier workability.

During the early European [[Renaissance]], a [[gilding#Fire-gilding|fire-gilding]] technique developed to produce an even and highly reflective [[tin]] coating for glass mirrors. The back of the glass was coated with a tin-mercury amalgam, and the mercury was then evaporated by heating the piece. This process caused less [[thermal shock]] to the glass than the older molten-lead method.<ref name=bonn2011/>{{rp|p.16}} The date and location of the discovery is unknown, but by the 16th century Venice was a center of mirror production using this technique. These Venetian mirrors were up to {{convert|40|in|cm}} square.

For a century, Venice retained the monopoly of the tin amalgam technique. Venetian mirrors in richly decorated frames served as luxury decorations for palaces throughout Europe, and were very expensive. For example, in the late seventeenth century, the Countess de Fiesque was reported to have traded an entire wheat farm for a mirror, considering it a bargain.<ref name=hads1993/> However, by the end of that century the secret was leaked through industrial espionage. French workshops succeeded in large-scale industrialization of the process, eventually making mirrors affordable to the masses, in spite of the [[toxicity]] of mercury's vapor.<ref name=iriw2018/>