Just for info, following up on a discussion a while back :)
I've just removed the faceplate on the CRT for an HP 250 that was
suffering from the dreaded mould. Used a bit of resistance wire as
someone here had suggested, and it was a remarkably easy job. Took
about ten mins to make it all the way across the CRT (although I was
only running from a 10V DC supply - I expect there's a lot of scope for
increasing the voltage without risk of damaging the CRT)
The sealant stuff pretty much just peels straight off the front of the
CRT / rear of the faceplate once the two are separated. A knife blade,
not water, and washing detergent shifted the rest and cleaned everything
up.
I'm not sure about trying to re-seal it; that could go horribly wrong
and leave air bubbles trapped in there. Not even sure what stuff to use.
Padding the faceplace out as necessary right at the edges (where it
won't be visible when everything's back together) is probably the best
course of action and it'll look as good as new when back together.
Next interesting task will be getting the paint off the 250's console
desk though - seems like when they were scrapped someone just went
around with a spray-can and put big X's on anything that was being
disposed of...
cheers
Jules