Re: DIY ground glass pumice

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From: John Cremati (johnjohnc@core.com)
Date: 07/09/02-02:43:00 PM Z


       If you use a Pumice grade 2F ( the coarser ) or 4F ( the finer of
the two) you will not visibly scratch the glass...... a major ingredient in
Bon Ami is "Feldspar" which is a major ingredient of optical pumice. I have
to assume that is what they are using as it is abundant and cheap...... It
is a crystalline mineral and I believe it to be used in Bon Ami in the
finer grades.....
         What you are calling pumice is volcanic rock which may consist of
other minerals which will in fact scratch glass .. the size of the abrasive
also means a lot... You can pre -polish glass with a 800 grit aluminum
Oxide or silicone carbide with out creating visible scratches but shore
nuff if you use 80 grit your gonna visibly scratch the heck out of it....
       Actually fine pumice and Bon Ami will "micro" scratch the glass
which is why it is used as a glass pre polish as well as a abrasive
cleaner, but again it is so fine that it is not visible with out
magnification....
       Sorry I do not know what the baby chicken and egg represents on Bon
Ami's logo but if there are egg shells or baby chicks in there, I just
don't know....
----- Original Message -----
From: "Jeff Sumner" <jdos2@mindspring.com>
To: <alt-photo-process-l@skyway.usask.ca>
Sent: Tuesday, July 09, 2002 2:27 PM
Subject: Re: DIY ground glass

> I always thought of Bon Ami as finely ground eggshells ("Hasn't scratched
> yet!") and it won't scratch glass, but I've scratched it with pumice (and
> ash- from Mt. St. Helens, on a parents good coffee table... Not a good
> scene)
>
>
>
>
> BonAmi is just fine
> > ground pumice and is used in a prepolish step to bring optical glass to
a
> > high polish....I would then coat the glass heavily and evenly and be
> patient
> > allowing extra time... You could apply several coats brushing in the
> > opposite directions..Any finger prints will cause the etching cream to
> work
> > slower in that area and cause a uneven etch..You may want to clean it
with
> > acetone as well prior to the buffing with Ami.....
> > ----- Original Message -----
>
>
>


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