brent3369
starting to shine!
Member since December 2014
Posts: 29
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Post by brent3369 on Dec 27, 2014 11:00:40 GMT -5
What polish is everyone using for soft stones like obsidian or dolomite?
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,158
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Post by jamesp on Dec 27, 2014 11:21:06 GMT -5
What polish is everyone using for soft stones like obsidian or dolomite? Aluminum oxide for me. Are you thinking about a softer polish ?
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brent3369
starting to shine!
Member since December 2014
Posts: 29
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Post by brent3369 on Dec 27, 2014 11:30:59 GMT -5
Years ago I used chrome oxide for everything. Now I have that and I think cerium or aluminum oxide.
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Post by johnjsgems on Dec 27, 2014 11:45:27 GMT -5
Best bet would be a sub-micron aluminum oxide (like .3 micron). Tough to get a really nice polish on soft stones in a tumbler. If you are using a vibe, the Vibra Dry compounds from Diamond Pacific work pretty well.
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stonemaster499
noticing nice landscape pebbles
Member since July 2014
Posts: 97
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Post by stonemaster499 on Dec 27, 2014 12:49:42 GMT -5
Cannot polish soft stones in a rotary! The problem with the sub-micron (ie .3 micron = 60,000 mesh) polish, is it requires additional steps. So you would need to go 1000 or 800 -->3000--->9000 (add this step for <4 hardness)--->18000--->60,000 (for soft stones only) ref - page 70 from Ed. E Smiths book, and creator of vibra dry product mentioned above. 1 micron polish (14,000 mesh) you can go from 1000 straight to dry polish (using any organic media - corn cob, walnut shell..etc.) If you are not getting a good polish, add one intermediary 1500-3000 step. If that fails, then you require the sub micron polish and all the standard steps listed above. I have not required a sub-micron polish yet, and starting the sand blue calcite (h.3). Does anyone know the mesh size of Tripoli? I think it is 1500-3000, so this answer will help me in a few days
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Post by Jugglerguy on Dec 27, 2014 12:57:00 GMT -5
I tried several times to tumble Kona dolomite in a vibe, but it always went bad in 500 grit. I've done a lot of Kona and Petoskey stones on a flat lap though. I always finish with a 1200 disc on the flat lap and then I use Zam on a felt wheel on a Dremel tool. The Zam really brings out the shine.
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Sabre52
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Me and my gal, Rosie
Member since August 2005
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Post by Sabre52 on Dec 27, 2014 13:48:58 GMT -5
More expensive polish than most but I get best results with tin oxide.....Mel
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jamesp
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Member since October 2012
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Post by jamesp on Dec 27, 2014 14:10:29 GMT -5
Does anyone know the mesh size of Tripoli? I think it is 1500-3000, so this answer will help me in a few days Tripoli must be in the 1000-3000 range judging by the finish it puts on soft base metals. It comes in many forms of man made matrix, some fast cutting and some slow. Not sure if it is the matrix or the abrasive that is the cause.
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jamesp
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Member since October 2012
Posts: 36,158
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Post by jamesp on Dec 27, 2014 14:47:18 GMT -5
Would a softer vibe help ?
There is a donut shaped hopper, vertical barrel and horizontal barrel. Which design could be turned down slowest and still circulate the rocks ? A donut hopper has to force the rocks from a large diameter to a small diameter to circulate the rocks.
Would softer abrasive/polish be a benefit ? Soft stones seem easier to finish best in a vibe. Vibes break down abrasive. Breaking down Mohs 9 polish ? With soft stones ? Why not use Mohs 7 polish ? Say quartz/garnet/diatoms/staurolite. Or Mohs 6 felspar Aluminum Silicate. Tripoli is Mohs 7 I think. Perhaps Mohs 5 powdered glass.
Ceramic media will help break down the abrasives in a vibe. Is that why 50% ceramic media is recommended for soft stones ? Wouldn't think plastic media would. Maybe if the abrasive is softer you could run with out ceramic media, and the soft stones would break down the abrasive quicker/easier.
Does the ceramic media cushion or break down the grit or both ?
Seems like soft rocks would polish faster. From what I hear they don't. Maybe most vibes are dialed in for harder rocks like quartz. Harsh metal tumbling vibes are hard on rocks. As the abrasives get smaller and closer to final polish soft rocks seem to quit abrading well. Seems that the polish level may require a softer vibe level.
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brent3369
starting to shine!
Member since December 2014
Posts: 29
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Post by brent3369 on Dec 27, 2014 15:01:49 GMT -5
Thanx for all the information.
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jamesp
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Member since October 2012
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Post by jamesp on Dec 27, 2014 15:17:15 GMT -5
Thanx for all the information. Welcome to the forum Brent. You asked a great question. The soft rocks present challenges.
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Post by captbob on Dec 27, 2014 17:12:22 GMT -5
Cannot polish soft stones in a rotary! pppfffffttttt..... (and other raspberry type noises) More expensive polish than most but I get best results with tin oxide.....Mel agree
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brent3369
starting to shine!
Member since December 2014
Posts: 29
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Post by brent3369 on Dec 28, 2014 10:41:31 GMT -5
I moved my dolomite batch into polish mode in my vibe tumbler. I decided to go with the chrome oxide since I didn't have any tin oxide. In just over twelve hours there is signs that shine is happening. will keep you all posted.
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Post by Jugglerguy on Dec 28, 2014 11:36:37 GMT -5
What kind of dolomite is it? I'd love to learn how to tumble my Kona dolomite.
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jamesp
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Member since October 2012
Posts: 36,158
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Post by jamesp on Dec 28, 2014 11:47:10 GMT -5
What kind of dolomite is it? I'd love to learn how to tumble my Kona dolomite. I will try some of the Kona dolomite soon. Rob, you sent me a slab that looks like bands of purple and black sparkly material. Can you tell me what it is ?
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Post by Jugglerguy on Dec 28, 2014 12:14:51 GMT -5
James, that sounds like banded iron formation or jaspelite.
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jamesp
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Post by jamesp on Dec 28, 2014 12:24:46 GMT -5
James, that sounds like banded iron formation or jaspelite. Is that from your area ? tumble well ?
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Post by Jugglerguy on Dec 28, 2014 12:27:56 GMT -5
It's from the U.P., but I'm not sure exactly where. I bought it at a quarry in Marquette. There is jaspelite in that area, but I think that quarry has another quarry in the western U.P. that it may have come from. I have tumbled some, but it didn't turn out great, just ok.
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brent3369
starting to shine!
Member since December 2014
Posts: 29
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Post by brent3369 on Dec 28, 2014 12:48:07 GMT -5
The dolomite is one I found a few years ago. I've named it glacier dolomite. It has many patterns and some of the rocks are over 1000 pounds. Anyone who knows me knows I like the big ones...lol.
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jamesp
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Member since October 2012
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Post by jamesp on Dec 28, 2014 12:49:37 GMT -5
It's from the U.P., but I'm not sure exactly where. I bought it at a quarry in Marquette. There is jaspelite in that area, but I think that quarry has another quarry in the western U.P. that it may have come from. I have tumbled some, but it didn't turn out great, just ok. Thanks Rob. The black part looks like petrified silicon carbide 220 grit.
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