Joerg wrote:

I think many of the German ones were melamine resin. My Aristo is really
sturdy. But yeah, in school I had a simple one that always got stuck
when it was warm and the old trick with "soap greasing" didn't work. I
don't dare to do that with a piece that cannot be replaced but I always
wonder what Teflon spray would do.

Usually graphite for tight ones and chalk dust for loose ones worked
pretty well. I have a K&E log-log decitrig. I even remember how some
of it works.

Cheers,

Phil Hobbs