Question

Why are door locks made of metals ?

Answer 1

Answer:

So brass effectively sterilizes the bacteria from all those hands turning the knobs. ... While brass remains the most common type of metal used for door knobs, stainless steel and plastic have grown increasingly popular (and cheaper) as a material choice—and that may be bad news for cutting back on the spread of germs.

Answer 2

Answer:

Door knobs are made of brass or copper, a chemical reaction helps to reduce this germ build up. It all boils down to what scientists call the "oligodynamic effect" .