[Eliot Ness]

It will work for older tubes that have a thoriated tungsten filament, such as the 01A and 99. I have successfully rejuvenated, maybe a dozen, 01A's years ago when I first read about it in an old publication called The Horn Speaker. Later tubes, even if they are globes, probably won't respond as well, if at all. In fact newer 01A's have an oxide coated rather than a thoriated tungsten filament so they will not respond well to the process.