I suspect that after a CRT type fell out of popularity, that there were no new versions of it being made. Even RCA reused glass envelopes for their Silverama tubes. Yet some Silverama tubes clearly stated "all new materials" on the box. I doubt there were any new evelopes being made for 10BP4's or 12LP4's into the early 60's. And to think that we used to drink soda from rebuilt bottles.
