fisherpal
off to a rocking start
Member since November 2012
Posts: 10
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Post by fisherpal on Dec 15, 2012 0:26:43 GMT -5
Being brand new to this fantastic hobby, we have been tumbling an assortment of rocks using 60-90 grit for four weeks now. These are pretty hard rocks and it wasn't until this last couple of weeks that we really started to notice some difference. Have been checking every 5 - 7 days, adding more grit, etc. There are no 'quality' stones in what we have - just an assortment of nice looking rocks we have picked up here and there. But ... that said ... some of them are coming along beautifully! I cannot believe how colors and patterns are popping out of them now! Anyway, my question is this. My husband is a 'use-whatever-you-have-on-hand' kind of guy. We don't have any of the next-step-up-grit on hand but we do have pumice and he is sure that would be good enough. I think it is far too fine for this stage and it ain't gonna happen! However ... has anyone ever used pumice for any of the polishing stages? I'm thinking it would work real well but I still know basically nothing about this. Thanks for any comments!
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Minnesota Daniel
freely admits to licking rocks
A COUPLE LAKERS
Member since August 2011
Posts: 891
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Post by Minnesota Daniel on Dec 15, 2012 2:39:30 GMT -5
Pumice is used as an abrasive or polish, but it's for glass or metal or your teeth. It's not that it's too fine, it's that it isn't hard enough. You can try it, but I don't think you'll see any change in the rock.
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Post by parfive on Dec 15, 2012 2:54:02 GMT -5
Pumice is too soft to do any good, about mohs 6. The rocks you’re tumbling are probably 7, silicon carbide grit and aluminum oxide polish about 9.
If you don’t have any 500 grit for the next stage, just let your final 60/90 course keep running for a few more weeks.
You probably already noticed 60/90 was more like 500 by the time of your weekly cleanouts.
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,564
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Post by jamesp on Dec 15, 2012 7:37:24 GMT -5
Aluminum oxide is cheaper.But it is hard to beat silicon carbide.If you polish metals you can use all kind of cheap stuff.If you live near a big city you can check with sand blasting companies to see if they have silicon carbide they want to get rid of.But it is usually coarse.I use more coarse grit than the other steps all added together. parfive mentioned running coarse till it is fine.i often wondered about doing that.
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fisherpal
off to a rocking start
Member since November 2012
Posts: 10
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Post by fisherpal on Dec 15, 2012 11:48:56 GMT -5
Thanks for your comments and tips everyone. You have confirmed my suspicions . I have to take a drive to another city today where there is a rock hobby shop - will stop in and see what they have for grit there. Hopefully in another six weeks or so, I'll have some pictures to post.
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Post by parfive on Dec 15, 2012 12:00:15 GMT -5
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Post by mohs on Dec 15, 2012 12:18:37 GMT -5
it would seem like the gradation of grit would break down over time and increasingly polish stone an interesting experiment - to start off with fairly rounded stones and enough time-- course grit --should succeed
and grinding wheels of the future that -get finer- as you grind-er
1 wheel magic ...mostly
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