but their steel fittings can and do.
I thought I'd done right by my molds by coating the sprue plate with Sheath and oiling the hinges well prior to storage. This has worked for my aluminum molds before, but when I took a couple of matched molds out for a casting session after couple or three month break, the sprue plates had rust on the edges and especially around the hinge bolt, whose bearing sheaths and wave springs were nearly frozen together
I think the problem is that the last session was the first time I used both molds for speed casting, where the sprues were water cooled on a damp towel after each pour. I guess water/steam worked its way into the hinge where the heat of sprue plate wasn't enough to evaporate it all as the mold cooled, and the oiling didn't penetrate enough to displace the moisture.
So once I manage to clean off all the rust I can go back to speed casting, but I'll have to disassemble, dry, relubricate and reassemble the fittings every time.
Live and learn...