exxos's Atari, Amiga & retro forum

Hi folks,

I was recently recapping an old 12" CRT which brought back its brightness. As an unwanted side effect, this now makes a scratch in the upper center of the screen more visible.

When googling I read that the typical auto glass repair resin wouldn't work, due to different glas properties and coating (which this one doesn't have, as far as I can tell) of CRTs and due to different refraction indices (as the CRT ain't flat).

Has anyone here any experience with repairing such scratches he could share?

I once tried to polish scratches out of a car window. I was recommended cerium oxide as a polishing powder.

peters wrote: 03 Jan 2026 21:49 I once tried to polish scratches out of a car window. I was recommended cerium oxide as a polishing powder.

Was that a flat surface or one with a curvature?

My only concern about polishing scratches out of a CRT is that if the scratch is particularly deep, then you risk weakening the screen.

Now of course a nice smooth polished out scratch is going to be much better than a jagged scratch as far as stress raisers in the glass are concerned, but there is always a risk of taking too much glass away and thus weakening it especially since there is a strong vacuum in the tube.

I'd try the car glass repair resin, especially if it's not coated, and the coating will be gone where it's scratched anyway. Of course it may give distortion, but is it worse then the scratch? Just use very thin plastic film over the top to make it a very thin layer so clean up after setting is a bit easier.

CRT glass is really thick. They are very hard to break.

I doubt losing 0.1mm is going to affect it.

peters wrote: 04 Jan 2026 14:35 CRT glass is really thick. They are very hard to break.

I doubt losing 0.1mm is going to affect it.

I'm not saying it will, but my Uncle was a TV repairman back in the days of CRT and always put safety first when dealing with screens that were scratched. I'm just saying think safety first when dealing with CRTs.

The other thing to watch for (which I cant see mentioned yet), is dont go too mad over a wide surface area if you are polishing out, as most (if not all?) CRTs were coated with an anti glare/anti static coating on the screen area.

Polishing this off may leave a bright 'patch' on the screen/ or uneven colour distributions, etc, which may be more annoying than the scratch.

Think carefully before proceeding. :)

mrbombermillzy wrote: 05 Jan 2026 19:48 The other thing to watch for (which I cant see mentioned yet), is dont go too mad over a wide surface area if you are polishing out, as most (if not all?) CRTs were coated with an anti glare/anti static coating on the screen area.

Polishing this off may leave a bright 'patch' on the screen/ or uneven colour distributions, etc, which may be more annoying than the scratch.

Think carefully before proceeding. :)

The "early" computer color CRTs - that are like our ATARI SC1224 - don't have a coating. That came later with matte coatings (e.g. on Eizo Multi sync CRTs).

As someone who has a car windscreen which has been repaired multiple times, the polishing out method rather than filling in looks 1 million times better. I've had both done and you can still see the "fill in" scratch but the polish out ones are imperceptible.