From: "Ellen Mackenzie" 
To: 
Reply-To: "Ellen Mackenzie" 


I have used burgundy pitch on machines for mirrors up to 24 inch diameter.
I temper the pitch with beeswax, 10-15%.I found that unless I held the
mirror(MOT)in my hands it is easy to develop an orange peel surface. By
holding the mirror in your hands you can feel the force and determine
quickly when the lap must be lubricated with rouge compound. For mirrors
over 12 inches I found it necessary to bond handles to the back of the
mirror with pitch so I could hold the mirror against the torque.
        If you are set on trying to polish completely with the machine--hands
off--then listen carefully for "singing" which creates orange
peel, from a dry lap.Patience is not only a virtue it is a necessity.

-----Original Message-----
From: owner-atm{at}shore.net [mailto:owner-atm{at}shore.net]On Behalf Of
Michael Burr
Sent: June 6, 2003 12:40 PM
To: ATM list
Subject: ATM Burgundy pitch/machine polishing



Greetings:

I'm about to place an order for pitch, and I am considering using Burgundy
pitch instead of Gugolz, which in my experience seems to be inconsistent
from can to can. I am polishing with a Mirror-o-Matic machine. I posted
this question to the MOM list, but I thought I'd also ask the ATM list.

Has anyone on the list used Burgundy pitch with their machine before? What
grade (soft, medium or hard)? Did you mix anything with it -- i.e.,
beeswax, rosin, talc, ... walnut shell flour? (Seriously.)

Also, Willman-Bell sells a "tempered" Burgundy pitch that has
rosin and beeswax in it. It's a bit more expensive, but they say it
"flows accurately for normal focal length mirrors and flats and is
consistent from package to package and year after year. This pitch is the
favorite of thousands of ATMs and professionals."

Would this tempered Burgundy pitch be appropriate for machine polishing?
I'm guessing the source of the W-B pitch has arrived at a happy medium that
its customers like, but it could be happy for hand polishing and very sad
for the machine. It seems to me that the beeswax would offset the effects
of the rosin, so what's the point of adding both?

From what I've read on the ATM list, burgundy pitch seems to be softer than
Gugolz, but I'm guessing it also has inconsistency problems.

Any thoughts welcome.

Regards,
MTB

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