showet
Cave Dweller
Member since June 2015
Posts: 65
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Post by showet on Aug 2, 2015 7:50:41 GMT -5
I have recently acquired some obsidian but I have never worked with obsidian before. I want to try some cabs.
Does anything really need to be done differently or just don't force things and be aware that it is prone to breaking?
Cut like any other stone?
Polish like any other stone?
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Post by rockjunquie on Aug 2, 2015 12:02:17 GMT -5
I can't really help except to say that obsidian is soft. It is a natural glass. There are soooo many kinds and some are treated much, much differently than others. So, you should mention what kind you have for the best answer.
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Post by broseph82 on Aug 2, 2015 13:10:37 GMT -5
It's soft but not that soft. You'll see. Go slow in the trim saw. Wear rubber gloves cause it's very sharp and can cut. Also wear safety glasses while trimming. Anytime I'm trimming glass there are shards that fly up. I've been hit in the eye a few times on those occassions I felt I didn't want the glasses on and now I wear them every single time.
Take your time with obsidian. If you don't you'll see by the time you polish where those tiny scratches or flat spot(s) are.
I've worked with quite a bit and always think I'm done on each stage and have always taken everything back down to the 280 again. I also use cerium on the buffing wheel at the end.
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Post by Bluesky78987 on Aug 6, 2015 16:20:25 GMT -5
Obsidian is a great stone to cab. My advice would be to dry it completely after each grit, and check carefully for scratches at each stage. I call obsidian an "honest" stone because the scratches show up very clearly on the black surface. Not like those sneaky agates where you only notice the scratch after polishing it sometimes! Once all the "big looking" scratches are out, move to the next grit. You will soon be able to tell which ones are the new finer scratches from the current wheel and which are the "bigger" scratches from the prior wheel that you're trying to get out. Also, for polishing, my best results have been with diamond on felt, with a little squirt of silicone lube, and pressing hard enough to build up a little heat. My current setup of diamond on leather isn't creating as nice a polish, but still ok. I've never had obsidian break on the dop stick. Broseph82 is right though, on the trim saw, little shards go everywhere. You might want to wear nitrile gloves or something to avoid the little stabs (I sometimes do, sometimes don't). If you are cutting sheen obsidian, such as rainbow or silver/gold sheen, other things apply too regarding orientation and polishing.
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obsidian man
off to a rocking start
Member since June 2015
Posts: 23
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Post by obsidian man on Aug 6, 2015 19:32:15 GMT -5
bluesky is on the money, if you are cutting say rainbow obsidian you have to consider it like a sliced loaf of bread, and cut with the layers. if you are off by a little and it's all diferent. obsidian from the davis creek pits are diferent than any other in the us. it seems to be brittle hence the fracturing to make all those crazy needle shapes! the rocks themselves are mostly mixed mahogany, but you can find any color of the rainbow there. I have been playing with obsidian for a while, and it is exactly like bluesky says the low spots or scratches you don't see when it is wet, will show up on the next sand, wipe dry often. it should help some. I just the opposite I have lots of obsidian and not hardly anything else, I'm working on that. good luck! I know I still need it.
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showet
Cave Dweller
Member since June 2015
Posts: 65
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Post by showet on Aug 6, 2015 20:28:45 GMT -5
So far so good. I got the preform cabs cut without any real problems. I tried not to cut them too close which proved to be good because they often chipped a little when I got to the end of most cuts. I will probably get to the shaping and polishing next week.
Thanks for all the input from everyone.
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