Lapidaryforum.net
Rock Art => Tumbling => Topic started by: William Phillips on September 26, 2018, 11:48:42 AM
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When using Aluminum Oxide as a final polish in my rotary tumbler should I use plastic pellets of ceramic pellets?
Thank You
Bill
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Unless the stones are very soft like obsidian I always use ceramic but try to damp down the action a bit by using less media.
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" When using Aluminum Oxide as a final polish in my rotary tumbler should I use plastic pellets of ceramic pellets? "
Plastic is best its soft then the material your tumbling.
And it well carry the polish better then the ceramic in the polish STAG.
Obsidian Moh-hardness 6.0-6.5
Ceramics MOH scale hardness 8.0 - 8.5
Myself i use Wallet shell soak overnight. Add wallet shell, add just enough polish to form a thin paste.
Though weight & type of rotary has a lot to do with the polish action.
15 lb. size an larger.
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Obsidian may have a high mohs reading but it acts like a mohs 4 when polishing.In any case aluminum oxide is really now considered a great all around pre-polish, not a general final polish.
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Okay then, what is the best final polish?
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There are a lot of proprietary polishes around and of course various grades of fine oxides but a guy who has tumbled hundreds of thousands of stones I used to work for used rapid polish. A long thorough prepolish has always worked for me as even in the vibe a long polish can sometimes help.When we ran grits through stone loads in the vibe we changed grits about every 5 hours with the exception of the polish and prepolish which may run a day.5 hours meant someone had to get up at night to change grits and you would have to add a bit of water to the oxides as well as they work better with just enough water to mobilize them and with only the recommended amount of water. On the other hand the man I know who supplied enough tumbled stones to museum stores and concessionaires in national parks to make him rich does not have water plumbed to his lapidary factory and never has had it. All processes totally dry!You can see that there is a huge range of ways to succeed.
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I'm gonna have to hear more about your tumbling friend sometime!
There are a lot of proprietary polishes around and of course various grades of fine oxides but a guy who has tumbled hundreds of thousands of stones I used to work for used rapid polish. A long thorough prepolish has always worked for me as even in the vibe a long polish can sometimes help.When we ran grits through stone loads in the vibe we changed grits about every 5 hours with the exception of the polish and prepolish which may run a day.5 hours meant someone had to get up at night to change grits and you would have to add a bit of water to the oxides as well as they work better with just enough water to mobilize them and with only the recommended amount of water. On the other hand the man I know who supplied enough tumbled stones to museum stores and concessionaires in national parks to make him rich does not have water plumbed to his lapidary factory and never has had it. All processes totally dry!You can see that there is a huge range of ways to succeed.
Sent from my SM-J327VPP using Tapatalk
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I've used both and prefer the ceramic media myself.. easier to clean out too!
Sent from my SM-J327VPP using Tapatalk
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A member of the old board TNT Mom mom has a great tutorial on tumbling obsidian she was known as the Queen of shine you can find the tutorial on the RTH (rock tumbling hobby forum) I'll se if I can find it and post.
http://forum.rocktumblinghobby.com/thread/52088/obsidian-rock-tumbling-tutorial
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Sorry, I should have been more specific. I tumble in a rotary tumbler and mostly agates or jaspers. They are what I trim from roughs when making slabs, or what is left from slabs when I cut preforms for cabs.
Bill
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My tumbling rules, sort of....
Well, I am not a mega tumbler but I use to do tumble polish about 100 pounds a week to sell at shows. It paid the overhead while I sold cabochons and jewelry. Also kept the kids busy while I spoke with mom and dad. Dry tumbling sounds interesting. How do you clean the rock with no water in the building???? intrigued I am
I never mix agates, jaspers and rocks of different hardness in the same load. You can do it and still get a nice polish, most of the time.
I rarely use media, almost never!!! I keep a bucket of small jasper pieces, about pea size, to add to the larger rocks being tumbled. The little pieces of jasper make certain the grit gets everywhere and grinds all the fresh tumble pieces from edge to edge. As a bonus you get some really nice small tumble pieces for decoration and to sell to crafters. I do the same for agates. Most instruction books say to use a mix of small, medium and larger chunks in any load of tumble rock. You have to have tiny pieces in the mix or use media. I choose tiny, it is a win - win....
I make certain to run the tumbler, rotary or vibratory, long enough for the grit to break all the way down. 7 days per grit on the rotary, usually 3 days per grit on the vibratory. I never use any grit higher than 500 in my vibratory tumbler so the barrel will last. On really rough rock I run the tumbler twice with 60 / 90 grit or else I rough off the hard edges with a 60 grit diamond wheel.
Thanks for the link to tumbling obsidian..............
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I use tin oxide as a final polish. Always gives me great results.