Raw ULE Body dirt type stuff...

[Thermus]

Theres some black stuff on a ULE body I just bought, almost like rust, and I was wondering if I could sand it or polish it out. Would polish work on a ULE body? Would sanding be bad even though its raw?

[MicroMiniMe]

Its probably just aluminum oxidation. It buffs right out. Otherwsie it might be some leftover lubricant from milling if its near some threading. That is sticky but wipes down with cloth after a few passes.