David Weaver
OK, not that stunning. Years ago, the wheel was slow, and I decided to use an abrasive rubber on the wheel (rubber, not abrasive, but for abrasive belts, etc). It cleaned the wheel off and made it like 80% of new again.

It's slow now and will burn AEB-L and V11 if you're not careful, but I just went out and tried the rubber again. Little change. I decided to scrub it hard with a grill brush style wire brush in case what's stuck to it is resistant to something like a rubber, and it did greatly refresh the wheel and cut back on the heat. It's no about half as fast as new, and cool grinding again (relatively cool), so that's a great improvement.

No clue what the thin layer was (it came off as dust when brushed, but didn't come off with the rubber).

The A24 wheel is still a lot faster working. The virtue of a 24 grit wheel like I'm comparing is that in 6" size, they're $17 at mcmaster carr. just under $30 for an 8x1 wheel.