michael adams wrote:
Maybe I got lucky and this was a one off and I've
checked Google - and nothing.

As before grip the lid with all your force, using
whatever additional help may be needed tea towel,
rubber glove etc.

Then take hold of the jar in the other hand

And er, turn the jar.

You can always get a better grip on a glass jar simply
with the width of your hand, given which it seems to
make more sense to turn the jar rather than the lid.
Which still needs to be gripped firmly, but not turned
at the same time.


michael adams

For commercial jar lids, you use a can opener, the one
with the triangle pointy bit on it, stick the pointy bit
under the edge of the jar lid. Apply a distorting force,
pulling the jar edge away from nominal position. This
will break the seal and allow you to turn it with ease.

Example of the can opener. The pointy end fits under
the edge of the jar lid. The rolling radius of where the
pointed part is bent, presses against the glass of the
jar, while you apply force. That's the fulcrum.

https://cdn.shopify.com/s/files/1/03...g?v=1598385093

Only apply enough force to distort the lid so that
the vacuum seal is defeated, not enough to permanently
damage the jar top and ruin it for home projects.

A second method, is to strike the jar lid (one side)
with the palm of your hand. This too can break the seal,
but is a much less effective technique and not
recommended. You strike the jar lid with heel of
hand, then revert to unscrewing the lid and see if
it's let go. There were some jars where this would
work, and others where it took too many strikes
to achieve a result.

The triangle can opener always works, because you can just
destroy the lid if so desired :-) Using the palm
of your hand, if you strike it hard enough, you
can take a chip out of the glass.

Paul