A mirror is an object that reflects light (and other kinds of electromagnetic radiation).
It is usually a glass plate with a thin layer of reflective material (usually silver or aluminum) on the back. This is protected with a few lacquer layers. There are also mirrors that consist of highly polished, flat metal or stone slabs.
Previously, was first blown a big sphere. A mixture of metal such as lead, antimony, and tin was cast trough the blowpipe. The pieces were never flat.

Mercury mirrors
spiegelglastrekkenMercury mirrors consist of a glass plate covered with tin amalgam as reflective layer.
For 400 years they used mercury to the difficult fabrication of mirrors. They put on a table with a trellis border a sheet of tin foil. Then they poured mercury on the foil. Which was rubbed into the tin with a cloth (or rabbit's foot). Thus tin amalgam was formed. Then they poured a layer of mercury on the film. On this a clean glass. Then a woolen cloth for protection, and stones to weigh. They needed about 3 parts of tin to 1 part mercury. Then they took away the slats to drain excess mercury. After a few days, the glass plate was tilted on a platform and increasingly put upright to continue to drip off and dry. So he stood there for about three weeks. This was laborious, time consuming and very unhealthy because mercury vapors are highly toxic. Mercury mirrors are now banned.

Breaking a mirror would bring seven years bad luck. What is not too bad given the long production time.

In the 19th Century a chemical method to provide levels of a layer of silver was found.
A glass plate is cleaned with cerium oxide, chalk and water. Then dried, and plated with silver nitrate. Because the thin layer of silver was a bit transparent and vulnerable, on the silver layer one of copper and two coats of paint were applied.

“What type of mirror you want, a hand mirror?”“No, I want to see my face.”

There are two ways of spreading light: you can be a candle or a mirror.

Working in a mirror factory is something I can totally see myself doing.