marlinguy wrote on Jul 27
th, 2025 at 7:32pm:
I never allow any oil around my molds! Oil for me has always caused contamination, and a real booger to get cleaned out of the metal. Wonder if it's the oil that's causing the issue for the sprue plate to lead up?
Ditto. I would no sooner introduce a petroleum product in or on a mold or clean it than I would so such to a seasoned cast iron skillet. Have I had iron mold blocks rust, or bought used ones that had surface rust? Yep, as has anybody who's been deep in the game. The thing is, carefully cleaning light rust with 0000 (oil free) steel wool won't hurt it and I swear I've had recalcitrant molds become sweethearts after having steel wooled rust out of cavities.
Heck, long ago I had a treasured Lyman .30 mold (311284) get horribly rusty after I haphazardly forgot to bring it indoors after an outdoor casting session. Heartbreak city. I figured I had nothing to lose so I bead blasted it inside and out and it remains today, 40 years later, one of my favorite molds and casts beautiful bullets.
New molds get washed in acetone, then I'm off to the races. I store my molds in the same environment I store powder and primers - cool & dry - and rust is very rare.
Everybody will get some lead smear at some point if they cast enough. It's especially likely if opening the mold too soon, and much more prevalent when using high antimony content alloys. When it happens, a quick lick with a single edged razor blade makes it go away. Having switched to binary alloys (tin/lead) for a large percentage of my bullets saw incidence of smearing recede greatly.