[meteorite-list] Hard to Polish Meteorites - Any Ideas? (diamond grit sandpaper?)
From: MexicoDoug <mexicodoug_at_meteoritecentral.com>
Date: Fri, 28 Oct 2011 19:29:23 -0400 (EDT) Message-ID: <8CE63E08F041527-DB0-D7D3F_at_webmail-d150.sysops.aol.com> Hi Mike, Trade secrets to sanding? Maybe you mean just the experience of knowing each meteorites favorite way to be sanded. It's kind of silly not to use deionized water to wet sand the specimens that you've determined look better that way unless we're talking about a stone that's never slept outside over night, if you can dry them after quickly enough. I appreciate your perfectionism of not wanting to allow water to touch your meteorites, but stony meteorites are like sponges anyway and soak up water. Dew tends to form on them inside your house if you're not careful or outside and they are porous, and once out of the oven will always be picking up water - they absolutely don't stay dry. All of the desert specimens which have been in the desert got tens, hundreds and thoudands of years have the unstoppable phenomenon of terrestrialization; that is dew cycles more than half of the nights, each night, every day of every year. The desert is especially prone to dew on meteorites, even though it is so arid it is another of those conundrums - why so much dew in the desert? Simple ... the meteorite is cold as stone in the morning and that is the time everything is the desert has most likely settled down in terms of winds which are what would normally wisk away the humid air before it cooled enough to deposit its dew. The core of the meteorite continues cooling the immediate air around the meteorite (this is infrared heating/cooling) faster than the radiative heating of the Sun can warm, so the go dew-dew on the meteorites all the time. This is accentuated by passing through the dew point of the air almost always in the desert due to the extreme day/night temperature variation, remembering even the dryest desert in the world has a lot of water still in it. The result is drplets of water all over the meteorite which collect and rust below it sometime for a long time. People in some places supposedly in the Atacama in prehistoric times used to pile up rock just to collect the water in them. Stone castle walls can have the same effect. In China, desert farming is accomplished by scattering gravel on the ground to take advantage of this and no additional irrigation is necessary in some cases. If you really are making a business of this and find yourself evaluating a capital purchase of costly equipment or holding off for the time being - and as posted want "diamond" sandpaper without having to buy a motor and disk or ready to use laping machine, and to do it by hand, there is no reason that you can't put nearly an equal finish on it over glass while purchasing the same polishing grit for the final step and impregnating it on some sort of shammy that you can be sure is clean of prior hard particles, exactly as you have been doing, wet or dry whichever works best for the piece. Of course 3360 rpm of a 6" diameter wheel at the edge will be traveling exactly a mile a minute worth of arm strokes. Kindest wishes Dioug -----Original Message----- From: Michael Gilmer <meteoritemike at gmail.com> To: Count Deiro <countdeiro at earthlink.net> Cc: meteorite-list <meteorite-list at meteoritecentral.com> Sent: Fri, Oct 28, 2011 5:55 pm Subject: Re: [meteorite-list] Hard to Polish Meteorites - Any Ideas? (diamond grit sandpaper?) 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 Facebook - http://tinyurl.com/42h79my News Feed - http://www.galactic-stone.com/rss/126516 Twitter - http://twitter.com/galacticstone ------------------------------------------------------------------------- -------- 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 >>>> ------------------------------------------------------------------------- -------- >>>> ______________________________________________ >>>> Visit the Archives at >>>> http://www.meteoritecentral.com/mailing-list-archives.html >>>> Meteorite-list mailing list >>>> Meteorite-list at meteoritecentral.com >>>> http://six.pairlist.net/mailman/listinfo/meteorite-list >>> >>> ______________________________________________ >>> Visit the Archives at >>> http://www.meteoritecentral.com/mailing-list-archives.html >>> Meteorite-list mailing list >>> Meteorite-list at meteoritecentral.com >>> http://six.pairlist.net/mailman/listinfo/meteorite-list >>> >>______________________________________________ >>Visit the Archives at >> http://www.meteoritecentral.com/mailing-list-archives.html >>Meteorite-list mailing list >>Meteorite-list at meteoritecentral.com >>http://six.pairlist.net/mailman/listinfo/meteorite-list > ______________________________________________ Visit the Archives at http://www.meteoritecentral.com/mailing-list-archives.html Meteorite-list mailing list Meteorite-list at meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-listReceived on Fri 28 Oct 2011 07:29:23 PM PDT |
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