For Sounding Balloons or Red Bull Stratos: Why not use hydrogen over helium

Like the dryness of acetylene when it comes from the tank. Can be quite sensitive to static and create - surprises.

It is sometimes hard to figure out some peoples' thought processes. "Let me think - what is it that allows me to stick a balloon to the wall, and what is it that causes my welding torch to ignite?"
Ethyne-deniers are simply Darwin Award fodder.