Re: ATM 21" f/6 report: status and questions

["Bill T." <twentiethwave@hotmail.com>]

Ken,

As Jeff Arnold pointed out, the jump from an aggressive Carbide 320 grit
(roughly 35+ microns) to a gentle AlOx 12 micron is a pretty big one.  Plan
on lots of time at 12 microns.  The jump from 12 microns to 3 microns is
unknown territory for me.  I usually stop at 9 microns.  I've seen several
grit/micron comparison charts, they all disagree substantially!

I've occassionally toyed with 5 and 3 micron AlOx wets.  It all boils down
to physical technique at the superfine grits - the big trick is separating
the mirror and tool.  I start to get little "sleeks" when I pull the tile
tool and mirror apart, areas about 1/4" wide and 1/2" long where the edge of
an outer tile took a swipe at the mirror surface.   Watch how things go
during 12 microns, and decide what to do after that.  The sleeks aren't
really serious, they grind off easily at the same grit -- but you may need
to make several trys to get a final, non-sleeked removal.

I'd sure like to get some pointers from somebody who's perfected fine micron
technique with clumsy, big mirrors and tools.

As far as I can remember the 3 and 5 micron mirrors didn't polish
dramatically faster than the  9 micron mirrors.

On my previous post I wrote "add about 1 drop/quart of cerox/water mix."  I
meant, "add about 1 drop of detergent per quart of cerox/water mix."   Duh!!

Bill T.