I noticed that it seemed to stay sharp until the abrasive almost
disappeared. Now I know why. It did a good job on the wood I was finishing,
BTW I used it with a small electric pad sander. It seemed to work fine,
though I don't know how it would have worked by hand.
From: Roger Gibbs [mailto:email@example.com]
As I understand these things, garnet is a mineral which easily
fractures, leaving sharp edges. As it is used, the garnet fractures and
two things happen: 1) the fracturing leaves new sharp edges, and 2) the
fracturing leaves the remaining garnet a smaller size, meaning your 80
grit paper becomes finer and finer.