How Come Early CRTs contained more Ions?

[Jeffhs]

Originally Posted by bgadow

It would show an image, if I zapped it with a rejuvanator and viewed in a dark room. All used up.

I didn't realize it was possible to completely "use up" the cathode in a television CRT unless the set was used 24 hours a day at nearly maximum brightness for years on end, and never shut off. I've heard of tubes with very low emission after years or decades of use, but this is the first time I've ever heard of one with absolutely zero cathode emission. The only other way this can happen, that I can think of anyway, is if someone tried to rejuvenate the tube and had the rejuvenator set so high it stripped the barium oxide coating right off the cathode.