On Jan 27, 2:47*pm, "Morgans" wrote:
"Stealth Pilot" wrote

*but my question
is, where does it come from, start, or what do you do to prevent it from
happening in the first place. *I did like your hints for dealing with it,
Jim in NC

Where does it come from? There is hydrogen all around when casting.
Comes from the propane(butane) burned to make the heat, from that oily
piston tossed into the fire, even the mayo on your hands from lunch.
I suspect those cooking with charcoal actually have less problems than
casters using the "cleaner" fuels.

What to do about it? Clean metal and some degas agent. When I melt
pistons and other salvage I never use it in the virgin state. Cast
some biscuits in your ingot molds and let cool. Then they are ready
to use, and in nice little chunks too :-) Toss in a little salt and
sidewalk de-icer, don't keep peeking at the pot, and you should be
good to go for the real parts.

Works for me. I've never noticed any problems with my castings, but
that doesn't mean there aren't some....................
===================
Leon McAtee