St Lawrence river valley, NY
Word of warning, this especially applies to Lee moulds- As you cast you may smear a little alloy onto the top of the blocks or bottom of the sprue plate. Carefully (it's REALLY HOT!) go after that smear with some 4/0 steel wool and then hit that spot, if you want, with a carpenters pencil. A little graphite seems to cover the raw metal and prevent further sticking/smearing. There is probably a newer way of dealing with it, but a cheap caprenters pencil works as good now as it did 40 years ago. If you don't fix it ASAP you run the risk of galling the aluminum. Lee moulds are very soft. Do not apply any forms of "mould release" spray on type snake oil. Just work at keeping the mould in good shape for now. The mould will surely stain and be discolored, and that's fine. But you don't want galling, so watch for it. It tends to happen more often if you aren't waiting quite long enough for the sprue to harden. Been there, done that, got the tee shirt!