I probably won't do this anytime soon, but I am interested in making small neon signs. Considering neon sign electrodes are hard to find and only come in diameters as small as 8mm (too big for my purposes), I would be interested in making my own if I ever get to do this.

I have the following questions:

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1) Electrode material:
I keep getting conflicting results as to whether nickel or iron is used. What if I used steel, stainless steel, aluminum, etc? Which easily accessible metal has desirable sputtering characteristics?

2) Activation:
Is it really worth it to activate the electrodes? From what I hear it only saves a couple hundred volts dropped across the discharge. I know barium carbonate powder is relatively accessible, but I don't know if it is worth it to add an extra processing step for very limited benefit.

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Thanks!

Just thinking, would it be possible to eliminate the electrodes completely ? What if you seal the proper gas mix in the tube, then near each end there is a section wrapped in foil, and HF HV is applied externally to those foils

Electrode material is either pure iron or nickel plated pure iron. Regular iron will likely give poor results because of high outgassing.

Neon electrodes are easy to get pre-made in fact. If you absolutely insist on making you own (which is hard to justify) you can cut some material from factory-made electrode and bend your own in a preferred size.

Electrodeless lamps are hard to get properly outgassed, surprisingly because of lack of any metal inside with its gettering action. A long oven bake is needed.

Plus you heed to heat the electrodes red hot either with of without activation, to outgas the metal. So not having an activation won't save you a process step.

@Ash
Yes that is possible, but I would prefer to have the genuine-ness of an actual electrode. Personal preference.

@RRK
Nice info, do you know specifically where someone could buy neon sign electrodes in sizes smaller than 8mm?

AFAIK, no factory made neon sign electrode available below 8mm. May be you can dig out some CCFL stuff in China. 8mm is an outer tube diameter, so it is already quite small. You can attach 8mm electrodes to 5-6mm tube. Small diameter neon tubes are quickly becoming tricky to make and run due to reduced gas volume and a combination of high ignition voltage and low working current, even 8mm ones suffer a lot!

6mm neon was practiced sometimes, in neon art and as scale decorations for cinema. But is tricky. Mercury filled tubes were said to work better, pure neon more problematic.