Quote Originally Posted by michaelbsc View Post
Somewhere, if I still have it, in an old ARRL handbook I have an article about making your own triodes. If I recall correctly you use mercury to scavenge the air in the sealed envelope.
Some of the old Vacuum pumps used mercury. It is too far off topic on APUG but their are a few hardy folks who have built there own tubes/Valves.

The existing commercial makers of Tubes tend to be from China and Russia and exist mainly on the Guitar market, often using tooling that was designed for Soviet Military production.

I would guess that the level of technology required to make a Black and White paper, and to make a vacuum tube are on the same order of magnitude. Unlike Film making, there is the posibilty to find the machinery that used to be used to rebuild Picture Tubes for B&W TV sets. The smallest setups would fit in a double garage and conatin the "tricky bits.

As far as Film, I an crossing my fingers taht one of Foma or Ilford can hold on and successfully downsize or diversify to fit the market.