RS at work fired this volley in news:45d6e4a8-
:


OK I can answe that. If you were to pressurise the outside of the bag
everything inside the bag would try to escape, including the stuff you
wanted to keep in the bag.

Think about a kid stepping on a packet of ketchup.

Roger Shoaf

Well, Roger, I think, then, that you missed something.

That "kid" is still at work when you pull a vacuum on the bag.

1) the contents will try to escape out the evacuation hole because,
2) the KID weighs 14.7psi at sea level, and he's stomping crap out of
your ketchup.

LLoyd