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So I came across a 75% off sale on opals and bought a few to try and cab.
First thing- they came covered in an oily substance. Hopefully not a stupid question, but was that just something they put on there to show the colors and can I clean them off?
And next, is there anything I should know before working them?
Thanks!
Too much walking shoes worn thin Too much trippin' and my soul's worn thin _______________________________
It's most likely because the seller believes the myth that coating or storing opal in oil prevents crazing. It doesn't.
Thanks...I just did a quick Google search and it seems like they do it so the opal doesn't dry out and crack- which doesn't sound good if I'm wanting to cab them. Not really into specimens. I probably should have done my research first- I'm old enough to know better. 🙂
Oh well, we'll see what happens!
Too much walking shoes worn thin Too much trippin' and my soul's worn thin _______________________________
Post by opalpyrexia on Aug 15, 2024 16:31:41 GMT -5
Go ahead and cab them, Mike. It's just as likely that the seller oiled them in order to get better photos. Capturing opal fire with a camera often feels like a fool's errand.
I wouldn't automatically assume that the opal you purchased is likely to craze. I've cut a couple hundred over the last 15 years, most of which are still in my possession. I can count on one hand the ones that have cracked or crazed. Well, maybe one hand and one or two fingers...
That’s a nice piece! It looks like jelly opal from Mexico. That one seems really large compared to what I’ve seen before.
Most of what I ordered is smaller but I can hopefully get some decent cabs. By the way, I still have the opals from you Brent, and I think I might have enough experience and confidence to work them now- I just need to find them in my rock stash! 🤣
Too much walking shoes worn thin Too much trippin' and my soul's worn thin _______________________________
Go ahead and cab them, Mike. It's just as likely that the seller oiled them in order to get better photos. Capturing opal fire with a camera often feels like a fool's errand.
I wouldn't automatically assume that the opal you purchased is likely to craze. I've cut a couple hundred over the last 15 years, most of which are still in my possession. I can count on one hand the ones that have cracked or crazed. Well, maybe one hand and one or two fingers...
😁
I'm going to give them a try, thanks Gary!
Too much walking shoes worn thin Too much trippin' and my soul's worn thin _______________________________
Looks to be Ethiopian water opal or Ethiopian crystal opal, not to be confused with Ethiopian welo opal, this opal is a non hydrophane opal so it doesn't absorb much water, and when it does start to dry out it will craze, crack and lose some of its flash, typically sold as specimen opal and to be stored in water or oil. Can you cab it, sure, will it crack most likely
Looks to be Ethiopian water opal or Ethiopian crystal opal, not to be confused with Ethiopian welo opal, this opal is a non hydrophane opal so it doesn't absorb much water, and when it does start to dry out it will craze, crack and lose some of its flash, typically sold as specimen opal and to be stored in water or oil. Can you cab it, sure, will it crack most likely
That's what I was wondering- and thinking.
Thanks for the response, I appreciate it.
Too much walking shoes worn thin Too much trippin' and my soul's worn thin _______________________________
Post by vegasjames on Aug 15, 2024 20:32:08 GMT -5
I agree that it is from the myth that storing in oil will prevent crazing.
Personally, I would try to stabilize the opal first to reduce the risk of fracturing. First by removing the oil then a common method to try and stabilize is to wet a paper towel and put the opal in it. Then put in a plastic zip lock bag. Some people put that bag in another zip lock. Then put somewhere that is temperature constant and leave for a year or two to allow the opal to stabilize as it slowly loses water. See my earlier post about opal being a gel and why it crazes for more details on why this can work.
When working opal, use a lot of water to keep the stone from heating up from the friction from the wheels, and lighter pressure to reduce heat build up.
I agree that it is from the myth that storing in oil will prevent crazing.
Personally, I would try to stabilize the opal first to reduce the risk of fracturing. First by removing the oil then a common method to try and stabilize is to wet a paper towel and put the opal in it. Then put in a plastic zip lock bag. Some people put that bag in another zip lock. Then put somewhere that is temperature constant and leave for a year or two to allow the opal to stabilize as it slowly loses water. See my earlier post about opal being a gel and why it crazes for more details on why this can work.
When working opal, use a lot of water to keep the stone from heating up from the friction from the wheels, and lighter pressure to reduce heat build up.
Thanks James, I read that also. Not sure I have the patience for a year- maybe I'll try it with the nicer ones. I also watched a video about soaking them in acetone and then using... something that starts with an x, I can't remember.
I did get some small "gift" opals with the order, I may experiment with those.
Thanks!
Too much walking shoes worn thin Too much trippin' and my soul's worn thin _______________________________
I agree that it is from the myth that storing in oil will prevent crazing.
Personally, I would try to stabilize the opal first to reduce the risk of fracturing. First by removing the oil then a common method to try and stabilize is to wet a paper towel and put the opal in it. Then put in a plastic zip lock bag. Some people put that bag in another zip lock. Then put somewhere that is temperature constant and leave for a year or two to allow the opal to stabilize as it slowly loses water. See my earlier post about opal being a gel and why it crazes for more details on why this can work.
When working opal, use a lot of water to keep the stone from heating up from the friction from the wheels, and lighter pressure to reduce heat build up.
Thanks James, I read that also. Not sure I have the patience for a year- maybe I'll try it with the nicer ones. I also watched a video about soaking them in acetone and then using... something that starts with an x, I can't remember.
I did get some small "gift" opals with the order, I may experiment with those.
Thanks!
The one you cannot remember the name is probably the epoxy HXTAL.
Thanks James, I read that also. Not sure I have the patience for a year- maybe I'll try it with the nicer ones. I also watched a video about soaking them in acetone and then using... something that starts with an x, I can't remember.
I did get some small "gift" opals with the order, I may experiment with those.
Thanks!
The one you cannot remember the name is probably the epoxy HXTAL.
Yessir, that's it. Thanks.
Too much walking shoes worn thin Too much trippin' and my soul's worn thin _______________________________
Post by hummingbirdstones on Aug 16, 2024 0:04:44 GMT -5
That looks like the chocolate Ethiopian that came out a few years before the Welo. I can't for the life of me remember where it was from in Ethiopia, but it wasn't Welo.
Robin
"Of all tyrannies, a tyranny sincerely exercised for the good of its victims may be the most oppressive. It would be better to live under robber barons than under omnipotent moral busybodies. The robber baron's cruelty may sometimes sleep, his cupidity may at some point be satiated; but those who torment us for our own good will torment us without end for they do so with the approval of their own conscience."
That looks like the chocolate Ethiopian that came out a few years before the Welo. I can't for the life of me remember where it was from in Ethiopia, but it wasn't Welo.
You may be thinking of Shewa, where most of the Ethiopian Chocolate Opal comes from. It forms inside thundereggs, so is presumably volcanic in origin, not sedimentary. Volcanic opal has a reputation for being "cracky." I've cut some that was cracky and some that was stable. I'm working on a piece right now but can't decide on a shape so I've set it aside to let my subconscious ponder it. I've ground on it a bit and so far see no sign of instability.
Use tons of water. Cab slow, stop and start. Fo not dry polish on leather etc. Put beautiful cab away to dry and A. Craze B. Crack C. Color will disappear D. Color disappears whole cabbing but comes back when dry
Learn to back, super easy Learn to put a top on the flat lapped opal and then cab, super easy.Do not use the freezer method to take off dop.
Opals are my fav
You can cab them so small that your dog is a toothpick
Worlds Greatest One Legged Cowboy turned rockhound lapidary nerd! LOL
That looks like the chocolate Ethiopian that came out a few years before the Welo. I can't for the life of me remember where it was from in Ethiopia, but it wasn't Welo.
You may be thinking of Shewa, where most of the Ethiopian Chocolate Opal comes from. It forms inside thundereggs, so is presumably volcanic in origin, not sedimentary. Volcanic opal has a reputation for being "cracky." I've cut some that was cracky and some that was stable. I'm working on a piece right now but can't decide on a shape so I've set it aside to let my subconscious ponder it. I've ground on it a bit and so far see no sign of instability.
Shewa, that's it! Thanks for relieving my brain of the stress.
Robin
"Of all tyrannies, a tyranny sincerely exercised for the good of its victims may be the most oppressive. It would be better to live under robber barons than under omnipotent moral busybodies. The robber baron's cruelty may sometimes sleep, his cupidity may at some point be satiated; but those who torment us for our own good will torment us without end for they do so with the approval of their own conscience."
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Welcome to the Rock Tumbling Hobby Forum where we share a love of rocks and a sense of community as enduring as the stones we polish.
The RTH Forum of www.RockTumbling.com is an Amazon Associate site and we earn money from
qualifying purchases you make after clicking on our links such as this
Rock Tumbling Supplies on Amazon
link for instance, or any of our various product ads and banners. By clicking our links every time you begin your Amazon shopping
experience, you are generating a bit of revenue for the forum which helps us cover our expenses. Thank you for your support!
