On Mon, 01 Oct 2012 23:35:35 +0100, The Natural Philosopher wrote:

Any idea what they might have used as a release agent?

Oddly enough, 'silicone spray lubricant'..

Think I'd much rather use a excess of physical barrier (aka cling film)
rather than spray stuff that might be a bit patchy. It wouldn't take much
not to release to have the window siliconed shut and working out where
that was to slice it through with a blade could be a right begger...

--
Cheers
Dave.