Platinum, Sonicap makes them..
I need to reread the jneutron stuff... If heat is totally negligible as you say, then what the heck is causing a change? Molecules are reforming, then why?
Ok so what I get out of it is electrolytics are cheap and just wear out over time because the fluid in them wears out/dissipates.
Metal caps "break in" due to oxidation caused by the voltage. Is that correct?