Can you put a tea bag in the microwave if it has a staple in it?
According to electrical engineer William Beatty, it’s fine as long as the staple is submerged in water. If metal is left unexposed in a microwave oven, the metal will deflect the microwaves and cause sparks. However, if it is submerged in water, the microwaves dissipate and are absorbed by the liquid. In turn, the water is heated.
Although one dry staple probably won’t start a fire, it can do some damage.
“It will be much the same as running the microwave empty, which could [burn] a hole through the microwave wall,” warns Mats Selen, professor of physics at the University of Illinois.