ATM 4.25" mirror progress report!

[BRYAN LEENHEER <BLEENHEE@millersqa.com>]

I've started on the grinding and the plaster tool.  I ground the front and
back plano on an old piece of flat steel plate I had lying around; took
about 1/2 an hour with numerous breaks for the X-Files. (oh the joys of
videotape!)  Once I had the face and back flat, I decided to experiment a
bit (shrug) and used baby oil on the front of the mirror, mixed up the
plaster of paris (I couldn't find hydrocal anywhere) and made a dam of
aluminum foil about 70% of the diameter of the blank. (Note:  there wasn't
any form of barrier between the blank and the plaster besides a thin film
of baby oil!)

The results were... um, well, OK.  The plaster set up quickly (I never
knew how fast it set; took about 45 minutes!) and I trimmed off the bit of
flashing that had slipped under the foil dam.  There wasn't much, really,
just a thin ridge which was easily trimmed off with a razor.  Then tried to
get the tool off the blank.  Veins popped out on my forehead, and my
thews strained mightily.  The idea of good ole' Porter for separating stuck
disks came to mind, and off I ran to get my clamp.  Tightened up and
heard a crunch noise.  Loosened it up and there was  a chunk of plaster
stuck to the clamp.  Wasn't that bad, though, just a chip from the back
side. I then went back inside to bemoan my life to my wife, and showed
her the predicament I was in, and while I was desticulating wildly (with
the disk still in my hand) the tool popped right off and landed right in my
other hand.  I still have no idea why it came off, but I am happy it did.  Will
I use plastic wrap next time?  Yup.  

Later!

Bryan