[meteorite-list] Hard to Polish Meteorites - Any Ideas? (diamond grit sandpaper?)

From: Michael Gilmer <meteoritemike_at_meteoritecentral.com>
Date: Fri, 28 Oct 2011 17:55:46 -0400
Message-ID: <CAKBPJW_pO_FWhyH964yUr5CJmi7EWNGsV9wcpwbao_afQM=Q4w_at_mail.gmail.com>

Hi Count and List,

You are fortunate to work with Adam firsthand and watch him work his
magic. It's no secret in the collector world that the Hupes do some
top-notch preparation work for all of their specimens. When I
purchase a meteorite from Adam or Greg, I know I am getting some of
the best preparation available, even if the specimen is a small micro.
 I wouldn't expect them to divulge their trade-secrets for
preparation, but I was hoping for a couple of pointers on how to
polish these hard to polish types.

The responses I have received in public and private have been valuable
and I am very thankful for the advice.

It seems part of my "problem" is dry sanding and part is the fact that
I don't have a lap-polisher. I guess I could do some wet-sanding,
using distilled water, but I don't like introducing moisture into a
specimen unless it is absolutely necessary. That is why the specimens
I prepare are stable and free of oxidation. The only water my
specimens see is during cutting (which is unavoidable) and then they
go straight into a hot waiting oven for 6-10 hours to purge all
remaining water. I use distilled water during cutting. Once the
pieces are dry, I don't like getting them wet again. But, I will try
some wet-sanding tonight and see how it goes.

Does anyone know if/where I can purchase some diamond grit sandpaper
for hand-sanding? I have been using the typical carbide sandpaper
from the local hardware store - 100, 200, 320, 400, 600. I purchase
higher grits online because they are hard to find locally without
paying an arm and leg - 800, 1000, 1200, 1500. But I don't recall
seeing any sandpaper with diamond-based grit. I'd like to locate some
if I can.

Right now I am polishing a gorgeous IMB meteorite for another dealer.
This meteorite takes a great polish, unlike the CR2 I am also
preparing. I'll be busy polishing most of the night and my right-arm
will be tired to the point of fatigue. I should have an incredible
Hulk right arm by now. On the bright side of hand-polishing - I am
learning to use my left hand/arm to good effect, once my right side
tires out. LOL

Best regards,

MikeG

-- 
---------------------------------------------------------------------------------
Galactic Stone & Ironworks - Meteorites & Amber (Michael Gilmer)
Website - http://www.galactic-stone.com
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---------------------------------------------------------------------------------
On 10/28/11, Count Deiro <countdeiro at earthlink.net> wrote:
> Hi Peter, Ed, Mike and List,
>
> I have spent a few days cutting and polishing dozens of various types with
> Adam Hupe'. With his guidance I set up my own shop with 6" and 8" saws and
> table and hand mounted polishing equipment. Basically, Adam uses quality
> diamond blades and arbor free polishing discs. Inspection cuts and slices
> are made with as fine a blade as will do the material in order to keep the
> kerf as thin as possible and reduce loss.. and at the same time eliminate
> the deep saw marks left by cheaper, thicker, blades.
>
> Polishing is accomplished with diamond impregnated discs both powered and in
> hand held blocks. He is a virtuoso with being able to turn our nice even,
> polished slices by hand. But, I never saw him dry cut or polish anything. He
> uses distilled water. This could be the secret, because when I used the same
> equipment dry, I couldn't get the same results until I added water for
> cooling and cleaning. The water also adds a fine abrasive sedimentary
> element to the polishing mix that I think is overlooked in it's ability to
> take up minute imperfections.
>
> Because of the fine (max.018) cut of his blades, I rarely found that I had
> to use coarser grained material to start polishing. Oh! Yes! It's really
> important to dress and clear the saw blade between cuts by running it
> through a piece of hand held common red brick. I could get by starting with
> 600 grit on small samples of friable material and move right into 1000 and
> then go on up. Bigger, harder, meteorites, or where I may have gotten ham
> handed with the saw, required 300 to start. Remember these are diamond
> impregnated polishing discs and hand held blocks like the type used by
> masons to finish counter top granite and marble. They can be bought in sets
> on eBay. I learned from Adam how to hand hold specimens safely while cutting
> and polishing. We both agree that there is something to feeling the pressure
> through your fingers on the stone.
>
> All of this seems, I'm sure, very ordinary and it isn't rocket science, but
> the key info here is to use the best diamond abrasives and the smallest
> diameter blades... and work by hand...and use water to carry off the removed
> material from the surface. Dry them out in the oven and fine finish wit
> ultra fine jeweler's non-resin cloths.
>
> P.S. Watch out for Urelites...they eat polishing discs.
>
> Have fun,
>
> Count Deiro
> IMCA 3536
>
>
>
> -----Original Message-----
>>From: Michael Gilmer
>>Sent: Oct 28, 2011 9:34 A>Cc: meteorite-list at meteoritecentral.com
>>Subject: Re: [meteorite-list] Hard to Polish Meteorites - Any Ideas?
>>
>>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
>>--
>>---------------------------------------------------------------------------------
>>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
>>---------------------------------------------------------------------------------
>>
>>
>>
>>On 10/28/11, Ed Deckert 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"
>>> To:
>>> 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 05:55:46 PM PDT