Originally posted by Yobgod:
<STRONG>I suspect that having no valid path to the melting objects helps keep the clean jobs down.</STRONG>
Nah, the dwarves just moan about not being able to find a valid path to complete their cleaning job.
I'm surprised nobody else mentioned it, but yes, molten objects will eventually melt completely in the magma. There are few materials that will survive exposure to magma (iron, steel and bauxite are the ones you'll most commonly come across, though off the top of my head I think adamantine is another, and graphite will burst into flames but won't melt)