|
Post by rock_and_stone on Aug 7, 2023 15:57:37 GMT -5
I tumbled a batch of iolite in a rotary through all 4 stages, and in retrospect, I probably should've asked questions about it on here before doing so. I took care to clean each piece with some Dawn and a toothbrush before moving them on to each stage, but they didn't take polish the way I'd hoped they would. Is there something I did wrong? Is there something fundamental about the material that I should understand?
|
|
tkvancil
fully equipped rock polisher
Member since September 2011
Posts: 1,546
|
Post by tkvancil on Aug 12, 2023 8:17:11 GMT -5
copied from Stone Mania
Although iolite grades 7 to 7.5 on Mohs scale of mineral hardness which makes it quite hard, it's not particularly tough. Hardness and toughness in rocks and minerals is not the same.
Hardness refers to the ability of one mineral to scratch another whilst toughness also known as "tenacity" refers to its resistance to cracking, chipping, pressure or breaking.
Iolite has a perfect cleavage in one direction which means it can break easily as result of a knock, pressure or even an extreme change of temperature. This makes cutting and polishing quite difficult
You might be able to salvage these by starting over at stage one and using a lot of cushioning along the way. Rock on...
|
|
|
Post by rock_and_stone on Aug 13, 2023 18:13:33 GMT -5
copied from Stone Mania Although iolite grades 7 to 7.5 on Mohs scale of mineral hardness which makes it quite hard, it's not particularly tough. Hardness and toughness in rocks and minerals is not the same. Hardness refers to the ability of one mineral to scratch another whilst toughness also known as "tenacity" refers to its resistance to cracking, chipping, pressure or breaking. Iolite has a perfect cleavage in one direction which means it can break easily as result of a knock, pressure or even an extreme change of temperature. This makes cutting and polishing quite difficult You might be able to salvage these by starting over at stage one and using a lot of cushioning along the way. Rock on... Thanks for that insight! I did use ceramic media in stages 2-4, so would you suggest I start over and use media in stage 1 as well?
|
|
iamchris
has rocks in the head
Member since June 2023
Posts: 668
|
Post by iamchris on Aug 14, 2023 10:05:04 GMT -5
It looks like the Cloudinary automatic resizing ate up a ton of the resolution and detail in the picture. Not that I'm competent enough to offer any advice other than IT support, but it makes it difficult to see what's going on.
|
|
|
Post by velodromed on Aug 14, 2023 22:23:07 GMT -5
copied from Stone Mania Although iolite grades 7 to 7.5 on Mohs scale of mineral hardness which makes it quite hard, it's not particularly tough. Hardness and toughness in rocks and minerals is not the same. Hardness refers to the ability of one mineral to scratch another whilst toughness also known as "tenacity" refers to its resistance to cracking, chipping, pressure or breaking. Iolite has a perfect cleavage in one direction which means it can break easily as result of a knock, pressure or even an extreme change of temperature. This makes cutting and polishing quite difficult You might be able to salvage these by starting over at stage one and using a lot of cushioning along the way. Rock on... Thanks for that insight! I did use ceramic media in stages 2-4, so would you suggest I start over and use media in stage 1 as well? What rotary tumbler do you have? The versions with multiple speeds tumble too fast for delicate rock tumbling, even on the slowest speed, so there are measures to take to avoid damaging the rocks. If you have a single speed tumbler…what is your process for loading it?
|
|
|
Post by rock_and_stone on Aug 14, 2023 23:01:35 GMT -5
Thanks for that insight! I did use ceramic media in stages 2-4, so would you suggest I start over and use media in stage 1 as well? What rotary tumbler do you have? The versions with multiple speeds tumble too fast for delicate rock tumbling, even on the slowest speed, so there are measures to take to avoid damaging the rocks. If you have a single speed tumbler…what is your process for loading it? These were tumbled in a Lortone 33B, though I just got a Raytech TV-10 (vibratory) a couple days ago that I also eventually want to try. edit: Forgot to answer your second question. I fill up the barrel with material up to about two-thirds to three-quarters full. If it's stage 1, I'll fill with water up to the top layer of material and then add 3 Tbsp of grit. If it's stage 2-4, I'll add ceramic media after the material and before the water. In between each stage, I empty out the slurry and then put everything back in the barrel and run it for an hour or so with a drop of Dawn. Afterwards, I scrub each individual piece and the barrel & lid with a toothbrush and more Dawn.
|
|
|
Post by rock_and_stone on Aug 14, 2023 23:06:34 GMT -5
It looks like the Cloudinary automatic resizing ate up a ton of the resolution and detail in the picture. Not that I'm competent enough to offer any advice other than IT support, but it makes it difficult to see what's going on. Sorry, I'm new here 😅 Will these work?
|
|
|
Post by velodromed on Aug 15, 2023 7:17:13 GMT -5
What rotary tumbler do you have? The versions with multiple speeds tumble too fast for delicate rock tumbling, even on the slowest speed, so there are measures to take to avoid damaging the rocks. If you have a single speed tumbler…what is your process for loading it? These were tumbled in a Lortone 33B, though I just got a Raytech TV-10 (vibratory) a couple days ago that I also eventually want to try. edit: Forgot to answer your second question. I fill up the barrel with material up to about two-thirds to three-quarters full. If it's stage 1, I'll fill with water up to the top layer of material and then add 3 Tbsp of grit. If it's stage 2-4, I'll add ceramic media after the material and before the water. In between each stage, I empty out the slurry and then put everything back in the barrel and run it for an hour or so with a drop of Dawn. Afterwards, I scrub each individual piece and the barrel & lid with a toothbrush and more Dawn. That’s a machine with proper speed and your process is good, so that is probably not the issue. At least if these were regular agate It wouldn’t be the issue. I researched that particular rock. It sounded similar to quartz at first until I read it has a several easy cleavage planes, so I understand it’s super delicate, more so than quartz. I think if I was going to try to tumble it, I would do it completely in the vibratory (I have a raytech 5) and very carefully. I would treat it like quartz basically, except I usually start off quarts with a gentle run in a rotary Tumbler with stage two grit. I don’t think I would do that with this rock. Straight into the vibratory, packed with ceramics, with 280 range SiC grit I think. I know the Raytech can be pretty violent unless they are loaded high, so I would definitely load it up. Good luck man! You got a challenging stone to tumble there. * I was just reading your response again and noted that when you ran it through stage one in the tumbler, you didn’t use ceramics. I think this rock is so delicate that if you do run it in a rotary Tumbler, you would have to really pack it full of ceramics and tumble carefully, checking often.
|
|
|
Post by rock_and_stone on Aug 15, 2023 19:43:53 GMT -5
These were tumbled in a Lortone 33B, though I just got a Raytech TV-10 (vibratory) a couple days ago that I also eventually want to try. edit: Forgot to answer your second question. I fill up the barrel with material up to about two-thirds to three-quarters full. If it's stage 1, I'll fill with water up to the top layer of material and then add 3 Tbsp of grit. If it's stage 2-4, I'll add ceramic media after the material and before the water. In between each stage, I empty out the slurry and then put everything back in the barrel and run it for an hour or so with a drop of Dawn. Afterwards, I scrub each individual piece and the barrel & lid with a toothbrush and more Dawn. That’s a machine with proper speed and your process is good, so that is probably not the issue. At least if these were regular agate It wouldn’t be the issue. I researched that particular rock. It sounded similar to quartz at first until I read it has a several easy cleavage planes, so I understand it’s super delicate, more so than quartz. I think if I was going to try to tumble it, I would do it completely in the vibratory (I have a raytech 5) and very carefully. I would treat it like quartz basically, except I usually start off quarts with a gentle run in a rotary Tumbler with stage two grit. I don’t think I would do that with this rock. Straight into the vibratory, packed with ceramics, with 280 range SiC grit I think. I know the Raytech can be pretty violent unless they are loaded high, so I would definitely load it up. Good luck man! You got a challenging stone to tumble there. * I was just reading your response again and noted that when you ran it through stage one in the tumbler, you didn’t use ceramics. I think this rock is so delicate that if you do run it in a rotary Tumbler, you would have to really pack it full of ceramics and tumble carefully, checking often. Thanks for all the insight! I will take it all into account on a future attempt. It's interesting to me that you don't start quartz with a 60/90 SiC grit? Is the shape as rounded and smooth when going straight to stage 2?
|
|
|
Post by velodromed on Aug 15, 2023 19:54:48 GMT -5
That’s a machine with proper speed and your process is good, so that is probably not the issue. At least if these were regular agate It wouldn’t be the issue. I researched that particular rock. It sounded similar to quartz at first until I read it has a several easy cleavage planes, so I understand it’s super delicate, more so than quartz. I think if I was going to try to tumble it, I would do it completely in the vibratory (I have a raytech 5) and very carefully. I would treat it like quartz basically, except I usually start off quarts with a gentle run in a rotary Tumbler with stage two grit. I don’t think I would do that with this rock. Straight into the vibratory, packed with ceramics, with 280 range SiC grit I think. I know the Raytech can be pretty violent unless they are loaded high, so I would definitely load it up. Good luck man! You got a challenging stone to tumble there. * I was just reading your response again and noted that when you ran it through stage one in the tumbler, you didn’t use ceramics. I think this rock is so delicate that if you do run it in a rotary Tumbler, you would have to really pack it full of ceramics and tumble carefully, checking often. Thanks for all the insight! I will take it all into account on a future attempt. It's interesting to me that you don't start quartz with a 60/90 SiC grit? Is the shape as rounded and smooth when going straight to stage 2? Not really. I tend to like a more natural shape to most rocks, so I put up with some blemishes and odd shapes. At first I tumbled quartz (amethyst technically) without much thought and it looked like crap, so I spent some time experimenting to get it to look how I liked. I don’t tumble it very often though. It’s kind of a pain. I’ve been collecting some local quartz though lately and I’m sure I’ll be dealing with some minor frustration when I start working with it.
|
|
|
Post by rock_and_stone on Aug 17, 2023 0:50:17 GMT -5
Thanks for all the insight! I will take it all into account on a future attempt. It's interesting to me that you don't start quartz with a 60/90 SiC grit? Is the shape as rounded and smooth when going straight to stage 2? Not really. I tend to like a more natural shape to most rocks, so I put up with some blemishes and odd shapes. At first I tumbled quartz (amethyst technically) without much thought and it looked like crap, so I spent some time experimenting to get it to look how I liked. I don’t tumble it very often though. It’s kind of a pain. I’ve been collecting some local quartz though lately and I’m sure I’ll be dealing with some minor frustration when I start working with it. Ah, cool! Much luck with the quartz! I'd love to see it when you're finished!
|
|
|
Post by velodromed on Aug 17, 2023 7:09:53 GMT -5
Not really. I tend to like a more natural shape to most rocks, so I put up with some blemishes and odd shapes. At first I tumbled quartz (amethyst technically) without much thought and it looked like crap, so I spent some time experimenting to get it to look how I liked. I don’t tumble it very often though. It’s kind of a pain. I’ve been collecting some local quartz though lately and I’m sure I’ll be dealing with some minor frustration when I start working with it. Ah, cool! Much luck with the quartz! I'd love to see it when you're finished! Ok cool, I have a running thread under rock tumbling photos called ‘Texas rocks’ and will put it under that when I eventually do it. Even though I have quite a few amazing store-bought agates and rocks, for right now I love tumbling the interesting stuff that we find around here most.
|
|
tkvancil
fully equipped rock polisher
Member since September 2011
Posts: 1,546
|
Post by tkvancil on Aug 19, 2023 9:06:01 GMT -5
I agree with the advice given in this thread. I haven't tumbled this stone but have done different feldspars which present similar challenges.
If we are doing all stages rotary here are some things to try...
Stage one cushioning ... ceramics or additional smalls could work, I would make them about 40% of the total volume. I would also make sure my tumbler barrel was filled to about the 80 to 85 percent range. This will slow down the action and it may take additional time to use up all the grit. Another idea, mix my target stone 50/50 with something softer on the mohs scale. In this case Iolite with something like Dalmatian stone or any rock in the 6 to 6.5 mohs range. I think the softer stone helps get a slurry going faster, the slurry its self can be cushioning. The other rock can generally be passed along with the target rock all the way to polish.
I have only casual observation to prove this ... straight graded grits for all stages seem to help over come or at least reduce many tumbling problems. For example I keep some 80 sic on hand which I use for things I already know undercut like many moss agates or have cleavage issues like feldspars. I believe it may be that the larger grit particles are forced deeper into the weaker areas by the tumbling forces. From there on 220 over say 120/220 then 500 and so on. One less variable in case of a "fail".
I would also keep overall tumbler volume at 80 to 85 in the steps between coarse and polish. Plastic pellets could be a consideration as well. Many folks here have success with them.
My "kryptonite" has been Labradorite ... looks just like I want it to all along and then goes to "crap" in the polish. Next time I do it I'm going to try a dry polish. I haven't tried a dry polish yet but many here have luck with it and difficult rocks so the info is here.
|
|