In a recent email, you mentioned the deterioration of the phosphor in a 15GP22 whose vacuum was lost. In our quest for a rebuild protocol only scant consideration has been given to the problem. Any speculation/experience you may be able to contribute on the subject of phosphor deterioration would be welcome and appreciated.
My comments about phosphor degradation are general, and not specifically about the 15GP22. Until a few years ago I worked for a company in nearby Vancouver which did warranty service for Emerson of Canada. When picture tubes were required we had to get them shipped to us from a rebuilder in Toronto. They very often arced and developed shorted guns in the first few minutes of operation. And when they did work they didn't look very good. I had to replace one tube three times before I got one that didn't short! That seems to have been due to poor cleanliness in the rebuilding process coupled with a very long shipping distance. That does not, however, address the fairly poor appearance of the picture. I got really angry about the situation and pretty much forced them to get tubes rebuilt locally. They never arced and looked VERY much better. The owner of the Toronto rebuilding company called me from Toronto to discuss the situation, and this gave me the clue as to why the tubes didn't look as good as the local ones. He said that at the end of their work day they would take all the tubes scheduled for rebuilding the following day and remove the necks. The tubes then sat there over night until the next day, exposed to air. I remembered reading some years ago that phosphors would be harmed by exposure to air for more than a few hours. So I talked to someone from the local rebuilder's place who told me that their tubes had their necks removed just prior to rebuilding, and that they were up to air for no more than half an hour. So there you have it. That's all I know about the subject. I have no idea where I might have read about this originally. Please keep me up to date about your project.
Best regards, Alan.
In case you didn't see it, I want to draw your attention to a new listing which appeared on eBay today. (www.eBay.com) Item 300041030, 6BD4 tubes (54 of them), opening bid $56.00, no bids as of this evening. The auction ends on April 8th.