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Author Topic: Removing soft materials with tumblers?  (Read 482 times)

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Shifter55

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Removing soft materials with tumblers?
« on: October 23, 2020, 09:42:33 PM »

After a lucky purchase of some royal imperial jasper and seeing an interesting image I have attached, I'm wondering something.

Would a vibratory tumbler be able to remove chalky material from jasper and eggs if I used a grit similar in hardness to silica like garnet blasting grit? What timeframe do you think it would take to remove a millimeter of material?

I want to see if I can expose and preserve the ripple pattern you can see at the interface between the jasper and leached out chalk surrounding the nodule, it would make an interesting sculpture if done with an intact nodule.
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Felicia

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Re: Removing soft materials with tumblers?
« Reply #1 on: October 25, 2020, 03:55:29 PM »

Never tried it but it sounds like a cool idea, will look forward to seeing the results.
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irockhound

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Re: Removing soft materials with tumblers?
« Reply #2 on: October 25, 2020, 06:30:44 PM »

When I got back from a couple trips I used to just throw a bunch of the nodules with caliche buildup on the outside in a tumbler with no grot for a day or 2, it did well to remover the softer stuff without grinding down the nodule much.  I think you would definitely soften the shape of it even without using the grit and only using more imperial but I have cut cabs of the soft/hard cross zone and it is quite a bit softer.  If you really want to keep the shape you might want to carve it or use a controlled process where your highest edges in tumbling will get hit the most.

ps that looks like regular Imperial Jasper,  "Royal" refers to the Orb patterned material.
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amrap1

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Re: Removing soft materials with tumblers?
« Reply #3 on: October 30, 2020, 04:30:49 PM »

Quote
Would a vibratory tumbler be able to remove chalky material from jasper and eggs if I used a grit similar in hardness to silica like garnet blasting grit? What timeframe do you think it would take to remove a millimeter of material?

I would probably try a tumbler with a soft filler like sawdust and a table spoon of 80 grit for 24 hrs and see what happens. But that's 'just me....

Did you try anything?

Ed
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R.U. Sirius

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Re: Removing soft materials with tumblers?
« Reply #4 on: October 30, 2020, 05:22:25 PM »

In rare cases where the crust is really "chalk" (that is, calcium carbonate), it is easy to dissolve it acid such as cleaning vinegar or other lime-removing product without harming jasper/agate/opal.

I don't think that's what you have here; it's either some form of tuff, or it is potch. Have you tried grinding to actually determine how it compares to the surrounding jasper? If it really is significantly easier to remove, tumbling might work.
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Shifter55

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Re: Removing soft materials with tumblers?
« Reply #5 on: October 31, 2020, 12:58:17 AM »

Did you try anything?
I haven't yet, still waiting on the grit to come, I don't know enough about fillers but I'm using some walnut.

In rare cases where the crust is really "chalk" (that is, calcium carbonate), it is easy to dissolve it acid such as cleaning vinegar or other lime-removing product without harming jasper/agate/opal.

I don't think that's what you have here; it's either some form of tuff, or it is potch. Have you tried grinding to actually determine how it compares to the surrounding jasper? If it really is significantly easier to remove, tumbling might work.
I checked and yeah, it's a layered tuff, it takes a deep scratch from the same jasper in the parcel. The chalky description comes from the white streak and very cloudy swarf when ground. We have a brecciated limestone filled with chalcedony veins here that behaves in the same way and mud leech/stains on agate do this too.
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lithicbeads

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Re: Removing soft materials with tumblers?
« Reply #6 on: November 01, 2020, 07:49:35 AM »

I use the vibe a lot and often use the ground corn cob with coarse diamond grit. It is very slow. I would use standard media in the vibe and 600 grit sic. Run it for 8 hours and it is worn out. Wash and inspect. Repeat if necessary. This conservative approach give you a lot of control  but is not interminable in duration .
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