Re: [ATM] How to grind and polish Slumped Mirror

[vorblesnak@peak.org]

Mahmood Hassan wrote:

> Hello

> I received a 9 inch slumped mirror blank in the Care Package last year.
I >want to offer this mirror to a person who is showing interest in
mirror >making.  The question is that "will this mirror be grind and
polished MOT >(Mirror on top) or is there any other strategy for slumped
blanks".
>
>
> Thanks
> Mahmood

The 16 inch is a slumped blank.  I ground and polished it mirror on top
using a full sized tool.  I received the slumping tool to use as a
grinding tool but I did not want to damage it.  So I built a paper dam
around the rim of the slumped blank and poured a concrete tool to use for
the grind.  Once it was hard I cleaned the surface well and used epoxy
glue to glue broken glass on the concrete.  I started with 320 grit but
that was a bit too fine for the irregularities in the glass.  So I dropped
down to 120 grit for a few wets, maybe a dozen or so, then finished the
rough grind with 220.

That blank was 3/8ths inches, or 9.5mm thick.  If I had it to do over I
would grind the back before I started on the front.  I ground the back
when I was done with the mirror because I was getting an odd reflection
from the back of the mirror.  It turned out OK but it was a nervous time
while grinding the back of a polished mirror.  Had I done so at the start
there would have been no problems later.

If your blank is one of Richard's engineered blanks, two pieces of glass
with ribs between them, all fused together, you can just grind it like a
full thickness blank.

David Davis
Toledo, OR 97391



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