CRT mold

[Gordon JC Pearce]

Loboyko Steve wrote:
> Sellam Ismail wrote:
> 
> 
>>One of the folks
>>here (I forget who it was) fixed a monitor with this
>>problem by using a heated wire to remove the
>>protective outer laminate and replace it 
> 
> 
> That was me. As dangerous as this was, I did take some
> safety measures; firstly, I made a plywood box in
> which to mount the CRT face up. (Needless to say, I
> wore a heavy long-sleeve coat, safety glasses and a
> hat at all times.) Then, I used nichrome wire
> (obtained from a hobby shop used in cutting foam),
> powered by +12 from an AT power supply as the cutter.
> Wooden handles with screws mounted in them held the
> wire as I cut through. I adjusted the length of
> nichrome to get just under dull red hot (having a
> high-current adjustable power supply would have been
> better). I worked pulling up towards the faceplate in
> order to avoid heating the face of the CRT, which
> might have had "undesirable results".

How thick is the glass?  The thicker the glass, the more likely a 
temperature gradient is to crack it, but the more heat it will take (if 
you see what I mean).

> I'm almost sure that some sort of optical quality RTV
> was used. It came off easily with acetone - so easy,
> that it might even be possible to remove the plate if
> you could suspend the tube in an acetone bath face
> down for a while.
> 
> Upon close examination, I'm certain that what these
> tubes experience is mold - the same type of mold that
> gets into the double-pane glass used in homes. This
> type of mold is actually capable of etching glass!

Might the damage be caused by acetic acid, formed by the RTV silicone 
setting?

> this desparate task. I think that there is some valid
> question as to whether this tube is as "safe" as it
> once was. I will say that the face of the CRT itself
> seemed quite thick (it would have to be, anyway). It
> may be that the bonded-on plate is an extra measure of
> safety or simply for anti-glare purposes.

I supppose the answer would be to get a "bad" tube (excessive screen 
burn, low emission, gone soft, physically damaged) and smash it open to 
measure the thickness of the faceplate.  It's easy to break up CRTs 
safely - just knock the evacuation tube off the end of the neck, air 
will rush in, and no, the tube won't implode.

Gordon.