Gary Syers, age 10, of Seattle Washington, for his question:

How are mirrors made?

A mirror is a sheet of glass with a special backing. A sheet of black paper on the back of the glass will provide a dim mirror. You can see a reflection if you put dark paint on the back of a sheet of glass. However, this reflection will be vague and distorted.

A good clear mirror, able to reflect sharp accurate detail must have a very even backing to the glass. A coat of silver salt solution is poured onto the glass end the excess silver rinsed away. The mirror now has an even coat of silver. Next a layer of copper is applied in an electrolytic bath. Then comes a coat of lacquer and lastly a coat of paint.

Good mirrors are made from fine, highly polished plate glass. Special mirrors are made for automobiles. Here lead sulphide is used instead of silver coating. The reflection from such a mirror is less brilliant, less glaring to the eyes of the driver.