What is a Mirror Made Of?
Mirrors are objects that reflect images. People have been making mirrors with stone, metals, and glass for thousands of years. Generally, a mirror is composed of transparent glass and a thin coating on the back. The layer on the back is both protective and functional. On one hand, it could protect the mirror against tarnishing and abrasion. On the other hand, metals like silver or aluminum are used as coatings to enhance the reflectivity of the mirror.
Why silver mirror is more expensive than aluminium mirror?
First, the prices of raw materials for production are different. It is well known that the price of silver is much more expensive than that of aluminum. So silver mirrors are of course more expensive than aluminum mirrors.
Second, the production process is different. The production of silver mirrors is a chemical reaction process, while the production of aluminum mirrors is a physical process.
The silvering process deposits a thin layer of silver onto the surface of glass via a chemical reduction of silver nitrate. The layer of silver produces a flawless reflection, while the glass protects the silver from corrosion, oxidation, and scratches.
The aluminum mirror is made in a vacuum sealed chamber in which aluminum coils are placed behind the glass in the chamber, this is what we called vacuum magnetron sputtering.
Different processing process determines the durability of the coating is different. The chemical process is much better than the physical process, so the life span of silver mirror is much longer than aluminium mirror.
