which can become brittle and crack under UV exposure.

Polarity occurs only HV technician jobs  the Leydenerflaschen and the discs are completely discharged. It can also happen if the slices are touching. If the machine is unloaded, a load on the disks must first again collect due to friction (brush on segments). This is negative or positive on a random basis. The pole shift is for only spark discharge but not further bad when double balls are used.
By the way, humidity and deposits (oxide) enhance the effect.
If you put value on the polarity, you can HV power supply with a DC (20kV upwards) determine the fundamental charge yourself...

kilovolt has written: ch wonder just how much distance the two plates in a self-made CD Influenzmaschine may have. On my machines, I have a distance of 2-3 mm. The lower, the better it works. seppo3 wrote: I thought that, that you could take even plexiglass rather than glass.

Plastic has the disadvantage compared with high-quality laboratory glassware, that it absorbs more moisture. It is possible to take plexi, but it only makes worse the vulnerability of moisture. I think also plastics would be first for's okay. At that size, I'd take happy plexi glass. Evt. which would then even the better dielectric properties than glass and would to increase the capacity of the Leyden bottles rather little. By the major shock resistance and durability made glass would however prefer me because this not changed over a long period, in contrast to plastics, which can become brittle and crack under UV exposure.

Polarity occurs only HV testing  the Leydenerflaschen and the discs are completely discharged. Hi Zqueeek, that makes sense. Probably exactly this at high air humidity and prolonged short circuit of the spark happens.