Re: Maybe metal dust...
Had to clean a computer used at for site-work at Sellafield. When the case was opened there was a thick layer of grime on the motherboard, deep enough to grow vegetables, if it didn't contain so much metal.
The only reason the motherboard hadn't shorted was that the Sellafield dirt was sitting on the dried mud from a previous site. As it was, the 386 happily chugged along regardless.