It grinds a new surface all right, it grinds the
surface right off!
I've never seen this thing but just a thought: were you grinding the
wrong surface (seriously)?
I think things would have to be pretty bad for me to use
a grinding product on a CD. I do have what is essentially
a soft pad (just to remove dust and prints and suchlike
from the surface) and I have seen various "CD
restorer"
kits (these seem to be mostly fluids that claim to fill in the
scratches and prevent them from interfering with the
data readback ... I'm not sure I believe that!)
Antonio