On Tue, 09 May 2006 21:26:14 -0000, Art Greenberg
wrote:

On Tue, 09 May 2006 13:56:01 -0700, pe wrote:

I have to disagree with this, at least related to some vacuum bags. My SO
has that vacuum storage system you see on the Home Shopping network.
http://www.comforthouse.com/spacebag.html She has a couple that have
stayed fully 'vacuum packed' for over two years. Some leak some don't.

Hardly the same amount of vacuum used in a press. Much easier to keep a seal.

Really?

The pressure developed by the vacuum bag is the result of creating a
pressure differential between the inside and outside of the bag.

The pressure outside the bag is ~14.7 lb/in^2 (psi) at standard
temperature at sea level. The absolute maximum pressure the bag can
develop is 14.7 psi regardless of how good the vacuum is inside the
bag. Sucking harder can't make it better.

So if you have a partial vacuum that leaves a residual pressure inside
the bag of 0.1 psi is this really a big deal? Is the veneer going to
lay flatter with an additional 0.1 psi?

And is it really that much easier to keep the bag sealed against a
differential of 14.6 psi than it is 14.65 psi?