Why magnesium ribbon is washed before burning the same?

Question

Why magnesium ribbon is washed before burning the same?

Answer 1

Magnesium oxide builds up on magnesium ribbon and needs to be removed before burning as it is unreactive i.e.it would stop the magnesium ribbon catching fire

Answer 2

magnesium is stored under oil to reduce the likelyhood of it combusting spontaniously, it is washed to remove the oil covering before being burned.