dano
off to a rocking start
Member since February 2008
Posts: 1
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Post by dano on Feb 7, 2008 16:57:48 GMT -5
bp1.blogger.com/_kJlOZYlKv3c/RrdfuqB2sWI/AAAAAAAAAtU/xy2Sw7p0ym8/s1600/3077.JPGThis is a link to the stone in slab form. I need help figuring out if this stone will polish up or not. I work at a slab shop and we had a green onyx slab break. I have tumbled it round, but so far I haven't had much luck getting a high polish on it. I know the slab was polished in slab form. This is only my third batch tumbling, but I had had good success with the other things I have tried. Please help me experts!!! Thanks, Dano
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Sabre52
Cave Dweller
Me and my gal, Rosie
Member since August 2005
Posts: 20,484
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Post by Sabre52 on Feb 7, 2008 18:54:21 GMT -5
I can't seem to get the pic up but it sounds like you have calcite onyx ( travertine) rather than true agate type onyx. Since rocks in the travertine group tend to only be maybe mohs 3-4 in hardness and often have bands of variable hardness it's very difficult to tumble to a mirror polish If you run four or five stage process starting with 110-220 fine grind or just a short run in coarse prior to fine grind, then move to maybe a 400 or 500 grit, followed by prepolish and maybe tin oxide or chromium oxide for final polish they might come out pretty decent with a satin finish. I'd use lots of plastic pellets in all stages to prevent surface glazing from having the stones knock together too much. You might check back through the old posts because I seem to remember someone doing pretty well on a lot of travertine a while back.....mel
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Post by Bikerrandy on Feb 15, 2008 22:15:59 GMT -5
Here ya go....
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181lizard
Cave Dweller
Still lurking :)
Member since December 2005
Posts: 2,171
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Post by 181lizard on Feb 27, 2008 12:58:23 GMT -5
Now THAT'S what I call a rock!
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Post by NM Stone Supply on Mar 3, 2008 0:00:38 GMT -5
Thats travertine onyx. Calcium Carbonate. I cut shapes tumble them for 3 days in a 400 grit and then take them out and polish them on a buffing wheel for a glass like shine. I use a white rouge polish. Jason
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