On Mon, 16 Jan 2006 09:49:35 +0000 (UTC), "Mike Deblis"
wrote:

How can you (non-destructively) test double glazing to see if it had
"popped" (lost its vacuum) without having to look for moisture inside etc.

The definition of "popped" pretty much depends on whether there's
moisture inside. Although they're "sealed units", this is just
bog-standard workshop air that gets sealed into them, dried out by a
dessicator pack if you're lucky. Only the good ones have anything else
as a special filler, and even then it's still atmospheric pressure.