Originally Posted by
onehundred80
You are the expert on this kind of stuff, but surely if a substance gave up its oxygen it would slowly or rapidly change to something else. I have not seen any of my abrasives disappear.
What am I missing? Inquiring minds and all that. 
Ok, "Inquiring Mind"! Here it is:
Assuming that one has trapped dust from an abrasive pad, Al2O3, Aluminum Oxide, will transfer some of its O2 molecules to the Pb, lead, over time. This is assuming a tight sandwich of materials. If one were able (as I am) to analyze the resulting layers using a 2 MeV He (alpha) beam and Rutherford Backscattering Spectroscopy (RBS), one would find:
Lead. Lead oxide. aluminum oxide/alumina mix. Lead oxide. Lead.
The lead is always trying to oxidize and will "leach" oxygen from any environment. Even air. This is why freshly polished lead or copper or magnesium or aluminum will change color (oxidize) overnight in the right conditions.
And this is why I had such an argument with Infinite a while back about the futility of polishing our intake manifold. How is Beaners' (?) polish job doing? Has it stayed nice and bright? I'm curious.
The same reason they oxidize so readily is the same reason they conduct electricity. Unfilled spaces is the valence energy band:
Why do metals conduct electricity.? - Yahoo! Answers
As to why your sandpaper sheets haven't morphed, they are in an oxygen-rich environment. (air). They have no reason to give up their oxygen.
Next?
