Which materials are mirrors made of?

Answer 1

While silver is expensive, a vacuum chamber for aluminizing is also expensive. I think one of the previous answers may have it backwards, since aluminum doesn't tarnish like silver, aluminum is preferred for most telescope mirrors, which are usually relatively small so the cost of a vacuum process is not such a big issue (and big telescope mirrors are so expensive that the cost a a big vacuum chamber is still not a big issue) It seems that despite the high cost of silver, the efficiency of atmospheric processing is still cost effective (the video referenced above mentioned a deposit of 70-80mg /ft² which is less than 5¢/ft²)

Some special telescope or scientific mirrors are made of fused silica rather than glass, and a few special mirrors are made of solid aluminum. For wavelengths of light outside the visible range, other metals may be coated on the substrate, for example gold is used for infrared.

Answer 2

Most modern mirrors are glass and aluminium. The aluminium is sputtered onto the glass in a vacuum, so it is deposited at the atomic level and sticks better than any glue. Sputtering involves heating the aluminium electrodes then applying a huge voltage so that the aluminium ions are accelerated away from the cathodes and towards the target, which in this case is the glass. Some are still made by wet deposition of silver, in this case the first layer is actually Tin then Silver and a backing of Copper or some other protective layer to stop oxidation of the silver (see the video at the link below).

Normal household mirrors are coated onto the back, so the glass protects the mirrored surface. In scientific mirrors, like those in telescopes, the metal is deposited on to the front of a polished substrate so that the glass does not distort the image.

Answer 3

Your regular mirror, like the one in your bathroom, is usually made from a polished sheet of silver bound to a sheet of glass.

Of course there's your variants, like type of metal, thickness of glass, and method of cohesion... What I mean by that is often in large scale manufacturing plants, the silver is submerged in slightly corrosive chemicals to polish it, and then a second which causes the glass to stick to it without leaving a residue. In smaller applications even in the dark ages, the molten glass was just made into a sheet on top of the silver plate.

Answer 4

Chris is right -- glass and aluminum. They don't use silver any more. Too expensive for anything but telescopes and microscopes.

Answer 5

silver is the shiny part and any type of surface. The silver coats the surface through an organic reaction.