Don't mean to necro my own thread, but I finally got around to trying Cerium powder and it did work. I couldn't find a post showing the work on a CRT (most posts talked about cabinet glass/cocktail glass...) so I figured it may have some value to others.
I will start by saying this CRT had some decent depth to the scratches. It was definitely put on concrete or pavement on it's face and moved around a little bit. The picture on the tube was just too nice to junk it so I gave this a try.
1.) I started out using a regular battery powered drill and it just didn't have enough RPMs to do any significant polishing of the glass. It would have worked eventually, but I would have had to charge the battery 4-5 times to complete the job and hours of polishing.
A high RPM drill is a must.
2.) This does get messy... I did it outside, but powder flung all over my damn siding and basement door. I was maybe 5-6 feet from my house so I should have done this in the middle of my yard and faced the CRT in a manner that wouldn't fling crap all over my house.
3.) I used a lot more Cerium than I saw glass professionals using on YouTube. I maybe used about 1/3 a pound (I purchased 1 pound of powder).
4.) Make the Cerium into a muddy consistency... at first everything was too wet... both the powder and my polishing wheel and it just shot everything all over the place and nothing stayed on the monitor itself (DOH!).
5.) Be careful of how hot the monitor gets... I was polishing about 15-20 seconds then stopping to feel the glass and wiped away the powder to examine the scratches. I have no idea how hot you can get the glass, but it if feels really warm you should just stop polishing for a few minutes and let everything cool. I was spraying down the glass at each break with water to help keep it cool and made sure the Cerium wasn't too dry by adding a little water to my buffing wheel and Cerium mixture if needed.
6.) Finally, it is a slow process so don't get frustrated and try to polish the damage all in one shot... Just go at it slowly and make more Cerium mixture if you have to... I had to 3 times... I also had to keep applying the Cerium like 14-15 times. If you get pissed you might screw up the tube or even worse make it exploded into your face. I've never had a tube blow up on me so I don't know how dangerous it would be, but I didn't want to find out. I also wore goggles and a mask just in case something decided to exploded and fly at me.
This took me about an hour total to completely remove the scratches in the top left corner in dead center. The scratches would produce a rainbow effect when any bright screens were displayed so it was either fix this or not use the tube in a game.