On 08/11/2020 16:19, Dave Plowman (News) wrote:
In article ,
michael adams wrote:

I mean I don't know. I've always turned the lids, but my recent experience
suggests that maybe I along with everyone else it seems has been doing
it wrong all along. As there's nothing that readily comes up on Google
about turning the jar instead.

The only problem is, I don't really want to go round opening jars of stuff
I don't need to open right now, hopefilly jars with really tight lids,
just to find out if it was a one-off or not.


Most of these things tend to assume the jar won't turn when you use them.
Never did work that one out.

I take a tight one to the workshop. Support it in the woodwork vice - not
tight, obviously - and use a couple of strap wrenches, one to stop the jar
turning, one to turn the lid. Most do open with Marigolds, though. ;-)

I don't think it actually matters which one you try to turn. Newtons
third law is relevant here and the grip with the weaker friction will
slip first. There might be a slight advantage therefore in using your
stronger grip on the smaller lid than on the body of the jar.

I find that for very stiff jamjar lids holding the lid and jar as hard
as I can out so that my arms cross at 120 degrees and moving the thing
sharply towards me allows me to put much more instantaneous torque onto
the recalcitrant jar lid than I can from just the wrist.

--
Regards,
Martin Brown