ATM Grey mirror after polishing!!

[arning@itn.is (Arni Ingimundarson)]

Hi all...

you might remember when I was posting with questions about my mirror
being gray after polishing.   Well I have found the problem !!

I was polishing with mirror on top and was probably using to much
CeO and did not finish each wet before adding more CeO.  And probably
more importand, I just added water or CeO on the edge with my machine
running.  The CeO nor the water did ever reach the center.  I discoverd
this when I had polished with TOT for a while with much better results
and wanted to try MOT again, but then the mirror was grey again, until
a stopped and added CeO and/or water to the center of the mirror.

Now all is going well and I have quite fine surface, I have not been 
able to spot any scratces but I was wondering if same did apply to 
finegrinding about adding more AlO to the center (MOT there to) because
I have less polished center than edges now?????


p.s. A friend of mine gave me a 4cm wide glass from and old radar display
(lots of scratces on it now) and it has about 40-50 cm focal length.
It is flat on one side.  Is there any use for this kind of lens for
astronomical use ???


--------------------------------
Arni Ingimundarson
arning@itn.is
Electronics Technician
Amateur Telescope Maker
Iceland.