When i was young and stupid i smoked a mold really bad and couldn't get the soot out once i learned how to actually cast lead bullets....
So i soaked this 6 cavity mold for 3 hours and took my trusty tooth brush to the mold. After years of cleaning and casting the mold is now carbon free.
I might actually keep this one now. It looks new like the day i learned to cast.
A 32 oz pump spray bottle can be bought for $1 @ most 99c stores.