From: "Bill T." 
To: atm{at}shore.net
Reply-To: "Bill T." 


I've had good results using 1/4" bubble wrap as a base for both
grinding and polishing.  Larger bubbles allow the mirror to rock too much,
but 1/4" gives a good solid feel.  I've used bubble wrap for mirrors
as thin as 18:1, without a hint of being near the edge of the envelope

When you put the wet mirror down on the wrap, observe the variation in how
the bubbles flatten out at different locations.  This gives a good
indication of the flatness of the surface, and/or how evenly made the wrap
is. With the wrap I use, the flattened bubbles have "air" between
them equivalent to about 50% of the diameter of the supporting part of a
typical bubble.  If you see a lot of variation in the diameter of the
flattened bubbles, rotate the wrap to see if you have a problem with the
underlying surface flatness, or inconsistency in wrap manufacture.

You lose a few bubbles each time you place the mirror, I go through about 4
or 5 pads to polish and figure a mirror.  With a cardboard template it
takes just a few second to cut out a new disc with a razor blade.

Bill T.


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