Hi there,
In a previous life, as part of my TV & video repair work, I used to sell ex- rental tv's from time to time. Mainly thorn 9000's, TX9 & 10, Gll's etc. I frequently had sets with scratches on the screen and if the scratch was vertical, it would interfere with the stripe of the phosphor and be very noticeable.
At the time, I bought a tube polishing kit from a company in Ware or Hoddesdon I think. I believe it was advertised in TV magazine.
It consisted of a foam cylinder about 4" diameter attached to a shaft which you mounted in an electric drill. There was a couple of different grades of sanding belt which went round the foam. The bulk of the scratch was removed with a fairly course belt and then finished off with a fine one. You were aiming for a fine matt finish over the surface of the tube where the scratch used to be.
Once this had been achieved, it was finally polished up with what I always assumed was jeweller's rouge. This was done wet using a different foam pad.
I achieved excellent results using this kit and got pretty good at doing it. I managed to get rid of some quite major damage- certainly no one ever seemed to notice!
I worked on the assumption that the tube face is pretty thick so would not be unduly weakened and I never had any problems. Whether this was a good assumption, however, I'm not sure. I did wear a breathing mask for the sanding down.
If I needed to do so, I would use a similar technique again, but would like to experiment on a scrap tube first to regain some experience.
Certainly, if I was doing this on a pre- implosion protected tube, (ie. one with a safety glass) I would wear face and body protection just in case
I have never tried on such a tube though.
Cheers Nick