[meteorite-list] Hard to Polish Meteorites - Any Ideas?

From: Michael Gilmer <meteoritemike_at_meteoritecentral.com>
Date: Fri, 28 Oct 2011 12:34:09 -0400
Message-ID: <CAKBPJW-qcwXRKdEh=frD6xQ+mMoQdpEKAdJH84WYvdvJLVaXEQ_at_mail.gmail.com>

Hi Peter, Ed, and List,

I know that the Hupes have a powered lap-polisher that most likely
uses a diamond grit. I need to break down and buy a lap-polisher
(flat lap). But I typically don't sand enough material to warrant the
expense of a flat lap. Also, I enjoy hand-sanding and find it to be a
zen-like relaxation exercise when combined with the right music. :)

But, every now and then I run across a meteorite that is stubborn and
won't take a polish. This is to be expected from friable types likes
LL6, most carbonaceous types, etc. But I know CR2 types are quite
hard and robust (also most CV3), so I expected this CR2 would be easy
to polish. Thus far, it has resisted my efforts to beautify it. It's
taking the polish, but the detail is becoming muddy and lost. I
thought it might be because I dry sand and powder from the sanding was
getting embedded in the matrix. So I tried giving the slice a quick
bath in alcohol, which removed most of the powder, but didn't improve
the appearance.

I have some 1200 and 1500 grit sandpaper, and I tried going straight
to those (skipping 400-1000), but the result is the same - muddy
matrix and subdued chondrules.

Best regards,

MikeG

-- 
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On 10/28/11, Ed Deckert <edeckert at triad.rr.com> wrote:
> Hi Mike,
>
> Perhaps the Hup?'s "trade secret" is using diamond polishing media at a much
> higher/finer grit than you are using?  It may be worth a try.
>
> Adam & Greg, can you share your secret?
>
> Ed
>
> ----- Original Message -----
> From: "Michael Gilmer" <meteoritemike at gmail.com>
> To: <meteorite-list at meteoritecentral.com>
> Sent: Friday, October 28, 2011 9:06 AM
> Subject: [meteorite-list] Hard to Polish Meteorites - Any Ideas?
>
>
>> Hi List,
>>
>> Some meteorites are hard to polish or just won't take a proper polish.
>> Allende is one example that comes to mind readily.
>>
>> I've got an endcut of NWA 801 CR2 that came from the Hupe Collection.
>> It has a wicked glossy polish on it that accentuates the chondrules.
>>
>> I'm working on some CR2 slices that need polishing and they won't take
>> a decent polish.  I can get the saw marks out, but beyond that I can't
>> get a polish to take.  The more I try, it just muddies up the matrix
>> and subdues the features.  The metal fleck and rings around the
>> armored chondrules come out nicely, but the rest of the specimen
>> becomes muddy and the chondrules fade into the matrix.  What am I
>> doing wrong?  This particular CR2 is similar to NWA 801, but a little
>> more weathered.  Could that have something to do with it?
>>
>> Do the Hupes have some magic trade-secret technique?  Or am I
>> overlooking something obvious?
>>
>> I started out with 320 grit and then progressed to 400, 600, and 800
>> grit - hand sanding, dry, on wet/dry sandpaper.
>>
>> Best regards,
>>
>> MikeG
>>
>>
>> ---------------------------------------------------------------------------------
>> Galactic Stone & Ironworks - Meteorites & Amber (Michael Gilmer)
>>
>> Website - http://www.galactic-stone.com
>> Facebook - http://tinyurl.com/42h79my
>> News Feed - http://www.galactic-stone.com/rss/126516
>> Twitter - http://twitter.com/galacticstone
>> ---------------------------------------------------------------------------------
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Received on Fri 28 Oct 2011 12:34:09 PM PDT