Also I would like to add on to some stuff I always thought was odd.

Like the tape on 120 films, some spark when you take the tape off the paper, some only when you take the tape off the film, and others don't spark at all if peeling slowly, other spark like crazy going fast or slow.

Also the little floaty things in xtol stock, they disappear when you shake it up but seem to precipitate out after a while when sitting.