ATM - Polishing questions

["Michael O'Neill" <oneillm@together.net>]

Hi, All,

I'm about three hours into polishing a 12.5" mirror, using CeO and
an 11" pitch lap.  The mirror surface looks very nice so far, and the
"feel" is good; no sticking or grabbing.  Of course, I know there are 
many more hours of polishing time ahead.  

Following suggestion in Tex, I'm polishing TOT all the way, and then I'll
switch to MOT for figuring.  Would it be advisable to change to MOT
for an hour or two occasionally?  I'm using the same table, rotating
at 10 RPM, that I used for grinding;  it seems to me that with the mirror
rotating I have the best chance of avoiding any astigmatic effects.

I've seen a lot of references to cold pressing of the lap, and I wonder
if this is something I should worry about before I get to figuring?  Could
someone explain to me in simple terms why cold pressing is necessary
at all?

Finally, is there any reason not to do some preliminary testing
before polishing is complete?  

Michael O'Neill
Shoreham, Vermont