RE: ATM How to pre-polishing

["Frank Ward" <thewards@mindspring.com>]

Alfredo,

You seem to misunderstand the physical properties of grit and CeO.

When grit (any size) is placed between two surfaces its sharp edges
shatters the glass around it. We use grit of smaller and smaller
size to make that damage smaller and smaller.

Then we use CeO on a pitch lap to shave off the tops of the craters
made by the grit. CeO does not shatter glass, it shaves it. (There is
evidence that it also reacts with water to form a chemical that dissolves
the glass too.)

When you put grit on pads it will just grind up the pads and scratch up
the glass. When you put grit on a pitch lap it too will shave the
peaks off the craters on the glass surface. However, because it is
so large it can only take off the tops of the peaks. This gives a
superficial polish  (a "flash polish" used for testing). That's its only
practical use....but if you then switch to a good lap and good 
CeO you will improve that flash polish to optical quality within
a few hours.

Frank Ward
Atlanta, GA