[high_vacuum_house]

Probably just a peculiarity caused during manufacture. I think that the white is where the gas jets would have been melting the glass and a tool being used to form the joint between the pinch electrode assembly and the glass bulb itself.

I have seen valves with white patches around the base and funny coloured getters but are all fine. Some clean B9a valves have quite powdery white looking bases inside.

Could be the glass to base cement but this is usually much darker and rougher.

Christopher Capener