sheriam
starting to shine!
Member since December 2019
Posts: 34
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Post by sheriam on Feb 17, 2020 12:52:42 GMT -5
And finally a question to this stone. From various posts I already gathered that it can't be tumbled, as it has holes and is porous. But what IS it? Is this something manmade or natural?
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whyofquartz
spending too much on rocks
So, Africa is smaller than I expected...
Member since December 2019
Posts: 316
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Post by whyofquartz on Feb 17, 2020 13:09:32 GMT -5
And finally a question to this stone. From various posts I already gathered that it can't be tumbled, as it has holes and is porous. But what IS it? Is this something manmade or natural? you *can* tumble this stone (if it is hard enough), you just have to be very careful and clean it really well when you change grit. As to it's origin, i don't know, wherever it came from lots of heat and rapid cooling were probably involved. molten rock that is cooled slowly allowed all of its gasses to escape and is smooth, rocks that were cooled quickly are full of bubbles, like Pumice stone
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Post by Starguy on Feb 17, 2020 13:39:24 GMT -5
sheriam I would definitely tumble that last stone. Many rocks will have pits, holes and cracks. Whether or not they can be tumbled out depends on what caused them in the first place. You should be able to tell if the pits and holes will be removed after a week or two in coarse grit. I run a 12 lb Lortone with coarse grit only. It is pretty efficient at grinding and shaping the rocks. It takes approximately 3-4 coarse grit clean outs to fill my smaller 3 lb Lortone with enough rock for stages 2 through polish. I use a separate batch of plastic pellets in everything but coarse. It takes the small tumbler 3-4 weeks to finish it’s charge, by that time the large tumbler has usually produced enough coarse ground rock to start a new batch in the small one. It’s not perfect but it’s the most efficient way I have found. I have had the 12 pound tumbler for years. It is on it’s 3rd rubber lid liner. The barrel is starting to get a little thin on the bottom but it still works. It has never run anything but coarse grit. Using the small barrel for polish keeps things interesting. I get to see a polished batch every 3 weeks or so. If I had to wait until there was enough rock ready for stage 2 to fill the 12 pounder, I think I would get bored. Sorry for the long reply. I can’t wait to see some photos of your work. PS. As described earlier, making your own plastic pellets is easy but time consuming. I found polyethylene plastic to work the best.
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Post by RocksInNJ on Feb 19, 2020 0:34:43 GMT -5
I’d throw them in the coarse stage and see how they look from there. You don’t need to get rid of all the holes. Just be sure to clean them out really well, so there is not grit transfer into the next stage. After running them in coarse, check to see if the rock is smooth. If so then it should be good to go for the next stage. If it feel kind of rough like sandpaper then forget it and don’t waste your time.
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