How come liquid glue doesn’t dry up inside the bottle when it’s exposed to air?

Question

Especially after using the same bottle of glue repeatedly

In: 22

Answer 1

Since the bottle has a small hole at the top, not much air moves in or out of the bottle. The glue needs a fresh supply of air to harden, so the hardening process takes a very long time. Also, the glue at the top of the bottle hardens first, since it’s in direct contact with the air. This helps protect the rest of the glue underneath it, but not entirely. Eventually, it will all harden. It just takes time.