I have a number of jadeite cabochons polished in Myanmar (I think using bamboo). Some reflect light nicely but others are rather lack-lustre. Might they be improved by western diamond dust polishing? I'd be very grateful for your opinions.
Joined: Wed Apr 26, 2006 12:44 am Posts: 2056 Location: San Francisco
Your issue will be undercutting and orange peel due to differential hardness in the way the matrix lies. I've had this happen with diamond. The best jade polish I have ever seen was done with a composite tin wheel on a hand grinder. Tin oxide seemed to do it.. mirror smooth, no pebble/orange peel, super reflective. He ran it hot.. It was a black composite matrix one. Fortunately the dealer shared with me his method as I had talked to everyone I know about how to do it..
Bamboo wheels may work with the natural bamboo silica.. let us know if you find anything else that works well
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I have gotten a good polish on nephrite by fine sanding it on the inside of a worn 400 grit silicone carbide belt then using chrome oxide mixed with vinegar on the finished side of a leather pad ran almost dry. Yes, a fair amount heat builds up as it polishes.
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Joined: Wed Apr 26, 2006 12:44 am Posts: 2056 Location: San Francisco
allen wrote:
I have gotten a good polish on nephrite by fine sanding it on the inside of a worn 400 grit silicone carbide belt then using chrome oxide mixed with vinegar on the finished side of a leather pad ran almost dry. Yes, a fair amount heat builds up as it polishes.
Yes that was one technique that was mentioned, using sandpaper that was used and loaded, so only the high points of the matrix were knocked off.. haven't tried acidic chrome oxide.. will give that a try.
_________________ Custom Gemstone Cutting and various other activities!
As a carver of jade I have used many different polishing techniques and compounds, jade, jadeite and nephrite can vary so much from one location to another, my preferred compound is diamond or linde A, but would rate diamond better, I purchase 3M diamond imperial exp drum belts, US made, these are the BEST I have used, grits from 1200 to 50 K, will make your jadeite gleam, loose grit diamond can still undercut but these work awesome, heaps of water is a must.
I have good luck using diamond powder and oil on hard wood (maple) with my carvings. I have a spool polisher for cabochons that I use with diamond and oil that is made out of some type of phenolic material; they are also made out of wood. An old-timer I know got great polishes on nephrite jade on diamond belts with a tiny bit of water; he said the secret was to run the wheels just dry enough for the jade to get hot.
I also have had good luck grinding and carving jade with different types of stones before I go to polish. I use Gesswein moldmaker's stones by hand, but I'm sure they make similar ones for rotary machines.
Here's one. It's a carved citrine head with tourmalines, herkimers, sapphires, peridots, rutilated quartz and tigereye. I hope it can post, if it's too big or I'm doing it wrong, please delete it.
Attachment:
Point of no Return.small.jpg [ 108.59 KiB | Viewed 1911 times ]
Thank you! And sorry that I've been spelling your name wrong!
I was rereading this thread and saw that Michael B had already commented. Listen to him; he is the master of polishing jade.
Jadeite is tougher to get a polish on than nephrite; as a matter of fact I'm dreading the next piece I'm going to carve as it is Burmese moss in snow type which I know will be problematic.
I also wondered whether or not the pieces mentioned originally had been waxed and that the wax had worn off. It's a common practice to immerse jade and jadeite in wax and then polish them. It's worth a try and easy to remove if it doesn't work.
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