[ATM] Polishing with WAO?

[Mel Bartels]

Squeaking:  For me and my students, squeaking during polishing occurs when
rapid polishing progress is being made, and occurs when sleeks are
suppressed. The squeaking likely comes from the pitch being rubbed over the
drying glass.  That means that much of the rest of the pitch lap is in close
contact with the glass, a good deal.  When too much pitch is in contact, the
tool cannot be moved against the glass.  Ask yourself if you've ever heard
squeaking with a pitch lap that you can finger push across the mirror?

Smoothness: I too have noticed that heavy slow work tends to produce smooth
surfaces.

Heaviness: I press as hard as I can, so the PSI is probably in the realm of
1 or 2 lbs/inch^2

Embedding pitch: Within a few minutes, the pitch lap should show the
discoloration of pitch that's embedded into its surface.  If you start with
a thick mixture (standard for me is 1:10 compound to water) and go slow, you
can start to feel a heavy drag right away.  Eventually the lap goes bad, and
acquires a bubbly aged look, performing poorly in that I've seen pits
reappear.

Extended polishing: I polish until inexpensive tests like lasers reflecting
off the glass show no more pits.  I then continue polishing for 50% more
time.  By the time figuring is finally concluded, probably there's 2x time
behind full polish.  The ultimate tests are 1) what does the coating look
like and 2) star tests for smoothness and scatter.  Many amateur made
mirrors are not fully polished out.  In the hands of amateurs, I've seen
mixed results in extending polishing time.  As often as not, it results in
an uncovering of the original fine grinding pits!

Extended polishing cannot be intelligently talked about without discussing
the particulars.  Some people need longer polishing times because fine
grinding ended with an undetectable number of deeper pits.  Some people
declare polishing finished prematurely, embarking on an extended polishing
sequence.

As for Carl Zambuto, there are many differences.  The biggest is that he's
in a production environment, where we necessarily don't know the
manufacturing and QA particulars.  Carl's a thoughtful investigative man
with a very real purpose: make money and make great optics.  If he says that
extended polishing makes a difference, then at minimum, I safely conclude
that it indeed exists to him in his situation with his production line and
QA methodology etc etc.  Since I do not know the exact particulars, speaking
further adds only speculation to a subject that enjoys way too high of
speculation to fact ratio.  

One way to help answer a question is to expand it, namely, do others
(whether telescope optics or not) employ extended polishing and if so, what
is the purported mechanisms?  If they don't use extended polishing, then
what is unique about CZ's production?

Mel Bartels