Re: [ATM] Polishing question

["Bob May" <rmay@nethere.com>]

First off, please change the way that you are replying to a
message.  My email address appears in the text of your message
and I really don't care to have a thousand or more pieces of
email coming to myt email box again as was with my old emailbox.
Large mirrors do tend to have more of a problem with pushing the
mirror around on top of the pitch and at about the sixteen inch
size, it becomes very diffic8ult to push evven a normal force lap
around.  There are techniques like microfaceting and thicker CeO
mixtures to help get the lap moving but they only go so far.
Eventually the lap will become a bit less sticky, especially
after the big pits are gone and the pitch can glide over the
smooth glass better.  Towards that end, I usually use the
polishing pads (eyeglass makers use them in place of pitch as
they don't change their shape over time) and that gets the pits
out without any problems with high friction while doing so.  The
only problem with polishing pads that I've seen is that they
usually end up with a TTDE due to the edge being ground a bit
more than the rest of the surface of the glass.  Polishing with
the lap on top does migitate this to a great extent tho.
For larger mirrors, the subdiameter lap is a must and those often
don'6t go over the twelve inch size.
Bob May
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