Doug Ferrell Xerox Desktop Document Systems writes:
>...
>...Upon finding some larger pits which measured
>from 3/1000 to 5/1000 inch across I decided to spend a little more time
>on the #220, hence the extra hour.
>...#001#
>...Having spent about 2.5 hours (same method as with the #220) I think
>I should be moving on to #400, but under a 10x loupe I see a mostly
>uniformly granular surface with some larger pits. These are about 2/1000
>to 3/1000 inch across. Are these small enough to be removed by #400 grit?
>It seems like they are to me, but I'd hate to waste a couple of hours
>grinding to find out.
-------------------------------------- Doug,
I remember my first mirror (10") years ago where I observed a uniform surface after each of the medium grits (200-600) except for a random scattering of larger pits. I spent hours chasing them until I marked some (with a permanent marker on the back) and found that they disappeared only to be "replaced" by others elsewhere. I finally decided to just go on to the next grit and they DID grind out. The worst that can happen is you waste some time. DO mark the larger ones first to determine if they grind out with the next finer grit. If you continue to get larger pits, you may have contaminated abrasives.
-- Tom Lum tom_lum@risc.sps.mot.com