if a jar lid is screwed on too tightly to remove, why is it sometimes possible to loosen the lid by heating it

Question

expain

Answer 1

if we heat then the lid expands
so it becomes easy to open

Answer 2

Yep ... could be the metal expands more than the glass ... so it loosens up. Could also be that whatever is in the jar softens when heated (or I sometimes loosen them with hot water and the water can dissolve some of the crusty stuff that can build up and cause the lid to stick).

Answer 3

Heat does 2 things, it expands the lid, and if the contents of the jar have sugar, it loosens the sugar holding the lid closed.

Answer 4

if the lid is metal-heat will slightly expand the lid and make it way eaiser to open. If the jar contains something sticky the heat will thin the gunk and give the same result.

Answer 5

The metal lid expands faster than the jar its screwed onto.

Answer 6

1) The lid expands more than the jar
2) Heating the stuff congealed in the threads of the lid can loosen it up

Answer 7

Normally metal has a greater thermal expansion than glass so if you heat the two the metal expands faster than the glass causing a release.

Answer 8

I've found it safer to stick a butter knife under the edge of the lid and gently twist, breaking the air seal. That way it opens easily.

Answer 9

because the metal band the top is made of expands with heat...and therefore it grows and loosens itself off the glass jar threads.

Answer 10

expansion. The easiest way is to turn it upside down and smack the lid firmly on a level surface,,,,be careful not to hit it too hard, but it breaks the seal, and opens easily