Re: [ATM] Acculap problems....

["Mel Bartels" <mbartels@bbastrodesigns.com>]

> Here's a conundrum for you: I'm teaching an ATM class (we
> have 18 college kids making 6" mirrors!)...and I'm using
> Acculap for the first time. After polishing for the 8-10
> hours it takes to clear pits, the kids started noticing a
> film on their mirrors. A few minutes of polishing with
> considerable pressure seems to take it off, but that, of
> course, plays havoc with the surface condition. So, has
> anyone else ever experienced this? It seems to be some kind
> of reaction between the Acculap and the plate glass (note,
> we're using plate, not pyrex)...or something similar. We're
> using CeO to polish. Suggestions?? I'd really like them to
> be able to finish their mirrors very soon.

The film is actually Cerium bound to the Oxygen atoms in the Silicon of the
glass.  This happens with certain combinations of pressure and wetness.
Almost always it comes from too little wetness and too little pressure.  So
I suggest (for polishing out, not for figuring) pressing much harder and
stroking slower.  A bit of wetting agent like a drop of soap or glycerin
will help too.

A minute or two of polishing releases the Cerium atoms so it's a cosmetic
issue, really.

Mel Bartels


_______________________________________________
ATM mailing list http://www.atmlist.net/