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Post by rmf on May 24, 2021 13:01:57 GMT -5
The problem with obsidian is if you push too hard it continues to scratch deep. Use a real light touch from 280 on. I normally stop at 3000diamond and go to tin oxide from there.
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Post by stephan on May 24, 2021 17:30:49 GMT -5
Light touch, throughout, definitely. I cut with the 220 wheel, as it is softer than agate, and can be quite brittle at 80 grit.
I semi-dry polish with 50k diamond or 100k CO, and let it get HOT!!! Once here (leather pad), moderate pressure is OK.
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Post by manofglass on May 24, 2021 17:51:05 GMT -5
I use super cerium oxide polish  |
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Post by stephan on May 24, 2021 22:31:46 GMT -5
3k or 12k, depending on the newness of the wheels. A new 12k side pad on the Genie can do some damage. Currently, my 3000 is pretty bald, and my 12000 is aggressive, so is skip the 12k.
Generally, I have success on obsidian when I follow the same practices as with nephrite.
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Post by stephan on May 24, 2021 23:47:24 GMT -5
3k or 12k, depending on the newness of the wheels. A new 12k side pad on the Genie can do some damage. Currently, my 3000 is pretty bald, and my 12000 is aggressive, so is skip the 12k. Generally, I have success on obsidian when I follow the same practices as with nephrite. Thanks for the additional info. My one jade carving is my only lapidary experience with jade, and I still haven’t attempted to sand and polish the thing. Honestly I love jade, but I can’t find enough great quality material to risk cutting without experience. I did get a chuckle when I read that you use similar techniques to nephrite. I cut obsidian for this month’s cab contest and it was like a chess match and an endurance race all wrapped into one hellish package. I ended up hand polishing with cerium on leather. Funny. With your screen name, I assumed you had a lot of experience with jade. Also, I find it interesting that people are so intimidated by jade. Granted, it can be challenging, but it’s also more forgiving than most materials, given that it’s so tough. It will rarely break (unless you happen to find a piece where a fracture was healed with gypsum). It’s also more forgiving than material that is prone to undercutting (plume or moss agates, poppy jasper...). In most cases, orange peeling can be resolved by backing up and using lighter pressure or deglazing wheels. Pieces with iron inclusions can be a bugger in terms of undercutting and uneven polishing, but those are low quality anyway. Decent jade isn’t too hard to find at shows, but I won’t buy it online, due to much of it being fake. |
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Post by stephan on May 25, 2021 0:33:35 GMT -5
That part is true. A lot of people seem to think they’re selling top-shelf Burmese jade. It can be right up there with rhodochrosite in terms of being over-priced. I was lucky enough to get a handful of slabs as part of one of the estate lots it bought.
One of these days, I want to go to the Big Sur jade festival. Just to drool, mind you. I don’t expect that adding jade and Big Sur together will yield anything approaching reasonable prices.
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Nov 15, 2024 17:44:51 GMT -5
Nov 15, 2024 17:44:51 GMT -5
