Re: ATM [long] Getting the smoothest mirror (no dog biscuit)

[Ken Hunter <kb7h@cei.net>]

At 02:59 PM 9/23/98 -0400, you wrote:
>
>There is a hard-to-define feeling when the lap begins to work, instead of
just
>drag across the glass.  I found warm pressing, and generous cool pressing
>finally brought my lap into real contact, and then I realized it had been
>skidding previously - not making 100% contact before.
>Larry Manuel.
>--

Larry,

You made a good point here that I have been negligent in mentioning 
because to me and most experienced ATM's it is too obvious.

When warm pressing...

DO NOT START POLISHING UNTIL LAP AND MIRROR COOL TO UNIFORM (ROOM) TEMP. 

Warm pressing will heat the mirror at the lap facets and the mirror will 
be a tad bit cooler in the channels. Result: Raised bumps on the mirror..
These bumps will give you very interesting but totally undesirable effects 
on the surface of the mirror if you try polishing when warm.

Sometimes we trip over the obvious because it is out in the open.
This may be a contributing factor to all the dog-biscuit msgs lately.