[cyberferret]

I'd be interested to learn more too. Old methods of tube production produced a lot of waste like Mercury and other toxic (carcinogenic) byproducts. I believe modern production methods (where they still exist) are better, and I bet this subject would make an interesting video/read in its own right.

[analognoise]

We should connect and try to figure this out - there must be more of us; maybe even dozens!