Zinc oxide

Zinc oxide is a fine white powder made of zinc and oxygen atoms in equal numbers (ZnO). It is one of the most useful simple compounds there is, going into car tires, paints, ceramics, sunscreen and diaper cream.

Making it is close to burning a metal. In the French process, zinc metal is heated until it boils, at about 910 °C, and the vapor is burned in air. It combines with oxygen and condenses into a very pure white smoke that is collected as powder. Other methods start from zinc ore instead of the metal and give a less pure product.

In a television, zinc oxide is an ingredient of ferrite, the dark ceramic used as the core of coils and transformers. Manganese-zinc ferrite is made by mixing iron oxide with oxides of manganese and zinc, then firing them together. The zinc makes the material easier to magnetize and lowers the temperature at which it stops being magnetic, so makers adjust the zinc content to tune each core for its job.

The same powder blocks ultraviolet light, which is why it whitens mineral sunscreens.