>> What is this CRT from again?
> It's a 30-year old CRT from a 30-year old computer. The surface is glass,
> AFAICT.
30 years ? That's not realy old - I had think of maybe
50 years, since I know special cases of degradiation
of old tubes from around the war, especialy when stored
in very dry (less than 60%) and warm (average 25 C)
conditions. But all of this doesen't affect the glass.
'Only' the coating around the tube (to keep light out).
and inside of the tube (sometimes additional coating
and of course the phosphor layer at the projection
screen).
The coating on the outside is often just turned to
dust on tubes of this or greater age, since they
didn't use any kind of ceramic material - often
just special kinds of paper, that turns out to be
very teperature and heat sensitive. When these
coatings have been kind of hard, they also suffered
from the expansion of the tube.
The coatings on the inside had only the teperature
and mechanical problems, and seam to be very stable
when stored properly and not to warm (I know TV sets
still working after 50 years!). But when exposed to
heat, the inner coatings also degenerate. I have seen
complete clear Braun tubes ... just some dust in one
corner...
Gruss
Hans
--
Ich denke, also bin ich, also gut
HRK
Received on Mon Nov 02 1998 - 09:29:47 GMT