Re: [ATM] Cerium Oxide.. and Color

[Guy Brandenburg <gfbrandenburg@yahoo.com>]

I have barnesite, I have pink cerium [di]oxide, I have
white cerium oxide, I have red rouge, and I have black
rouge. They are all different.

The pink cerium oxide sold by Willmann-Bell is
probably pink because of some impurities, but I don't
think the impurities are Barnesite. Barnesite is
brown-ish, not pink, and frankly doesn't work very
well. It works slowly, it appears to me, and produces
a very rough surface. Previous posts on barnesite
(many years ago) in this list established (?) that is
really is NOT radioactive.

I suspect the real reason that use of barnesite was
discontinued is because it sucks as a polishing or
figuring agent.

Guy B

--- Lawrence Sayre <lsayre@neo.rr.com> wrote:
> Russell Jocoy wrote:
> 
> >
> >
> >     Geoff,         I would question the cerium
> oxide of a different 
> > color... From the white color
> > it sounds , or feels like Aluminum oxide... 
> 
> 
> All of the chemical properties websites I visited
> upon doing a search 
> for "Cerium Dioxide" (the true name, its formula
> being CeO2, and with 
> mainly the ATM crowd distorting this to 'Cerium
> Oxide')  stated that the 
> color should be pure white to very pale yellow (with
> the latter color 
> being for less pure grades, I assume).
> 
> All of the CeO2 sold by 'Salem distributing' 
> (perhaps the largest 
> distributor of glass grinding and polishing agents
> in the US)  is white, 
> in my experience.
> 
> For years many of the ATM old timers used a compound
> called "Barnesite" 
> [chemical formula: Na2V6O16·3(H2O)], which is red. 
> I believe that 
> Barnesite was (voluntarily?) taken off of the ATM
> market for some reason 
> that I can't remember, but I seem to think it was
> either a proclivity to 
> have trace to moderate radioactivity, or its
> toxicity level, with my 
> strong gut feeling being that it was for the former.
>  Barnesite is not 
> to be confused with Rouge, but its action was more
> akin to the slow 
> action of Rouge than the quick action of Cerium
> Dioxide.
> 
> If some Barnesite was mixed in with Cerium Oxide, I
> would assume the 
> resulting color to be pink.  I'm not suggesting that
> this is in fact 
> happening, but I'm just thinking out loud (through
> my fingers) here.
> 
> Lawrence Sayre
> 
>  
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> 

Guy  Brandenburg
Washington, DC
My home page:
http://home.earthlink.net/~gfbranden/GFB_Home_Page.html
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