Lapidaryforum.net
Rock Art => Cabochons, Intarsias, Cameos => Topic started by: rockherder on July 30, 2017, 11:14:24 AM
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This is such a great group.
I really enjoy reading what folks are doing and how helpful everyone is.
I need some help with a recent Jade Cabochon.
I have a slab of this green jade.
I created a cabochon from it but can't get it to polish.
There are dull spots in it that don't seem to brighten up.
I'm using a leather wheel with super cerium oxide.
Any ideas on what might work?
Do I need to seal this stone with something.
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Micheal Hoover (reddrum) has a good tutorial on Jade.
I really like Jade but it can be a PIA sometimes. I sand it to 6,000 diamond
And than polish with Linde A on leather (rough side) I let it dry a little intill
Stone drags. I let it get pretty warm but not to hot to touch.
Is that Wyoming jade? Some of it seams to take a polish like
That, it may be the best you are going to get.
I am not an expert I just like working with jade
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The critical stage for a stone like that is the 1200 stage.If the stone cannot be made close to a polish at that stage polishing will not make up the difference. Wet the 1200 sanding wheel and sand until the stone is tugged or grabbed by the wheel. Repeat. Fine polishing can exacerbate undercutting in jade so you may need to go back to 600 sanding and start over. We sand wet with the wheel very thoroughly then take the water away and bring the stone to the tugging stage all over the stone. Often the 1200 grit polish using the wet then the work till dry technique is superb. These are fairly well used diamond sanding wheels. Another trick that works well is to use a 1200 well worn flat pad on the stone. Wet it and work until very dry and repeat. Some jade cannot be polish but most jade can but it often needs a bit of dry sanding just like in the old days with very well worn 600 sic belts.
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And than polish with Linda A on leather (rough side)
Excuse me Jhon, but that should be Linde A not Linda A. Linde was the division of Union Carbide Corporation that developed the synthetic aluminum oxide (Al2O3) abrasive that is now known as Linde A. There are other grades but A is the one most of us use.
Normally I would not correct a typo like this because most of us that have been working in lapidary know what it should be. However, newbies out there reading this would not be able to find the correct material. Usually if there is a misspelling, the search engines will catch it. But to make sure before I posted this, I checked 4 of the major ones (Google, Yahoo, Bing and Duck, Duck, Go [my favorite because it doesn't track you]) and not one of them led to the correct information.
Jerry
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iPhone **#% auto correct. That wasn't the only goofy thing I hope it makes more since now
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Thank you everyone for your replies.
Much appreciated.
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If the rock contains harder and softer minerals it will not be possible to obtain the same consistent mirror polish on the whole surface by definition. Softer minerals take less of a polish than harder minerals. For example a rock like chrysocolla in quartz has softer chrysocolla particles floating in harder agate. So when you polish this rock the softer chrysocolla parts will "undercut" and polish at a more satin level compared to the mirror polish on the agate. Having said all this IMO you need a perfect prepolish surface before going to final polish to obtain the best possible finish. For jades I final polish with either Linde A, Tin Oxide, or Poly-Al F on soft leather.