jamesp
Cave Dweller
Member since October 2012
Posts: 36,562
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Post by jamesp on Feb 23, 2015 15:56:31 GMT -5
Here is a polish on silicified oyster after 24 hours in clean garnets. The high spots on this stone took a fast polish from the garnets. It had been run in SiC 30/60 in the rotary before. Hope it does that to the rest of the stones.
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,562
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Post by jamesp on Feb 23, 2015 18:15:28 GMT -5
You can buy garnet grit from Home Depot for $28. Any better deals? Dave, I do have garnet grit. I use 100 and 300 on some stuff. But it is just a softer grit. A sharp grit that cuts(sharp garnet particles). It is a pain in the vibe, it is slow to break down. Garnet is one of the toughest abrasives on the market. Fairly soft, but the about toughest abrasive for the cost known. If tumbling with smooth garnets (5 grit in this case) the effect is very different. Looking at ceramics, many are Mohs 8, but I believe they are fused particles. Not sure if they will impart a polish without adding abrasive and thickener. If ceramic filler takes a polish, then it may impart a polish without adding abrasive on material softer than it. Previous mention of using polished well rounded crystalline quartz pebbles as media with AO 500 on obsidian in a vibe had great results. Not sure if the polished Mohs 7 quartz pebbles are adding to the polish on the obsidian. Or are they breaking the AO 500 down fast. Or both... actually it has to break the AO 500 down, or there would be no polish. that is a given. There is a possibility the polished quartz pebbles will polish the obsidian without any abrasives added. One thing I do know, is the smooth garnets laid a polish down on hard coral with out abrasives being added starting yesterday. So smooth media has a definite effect in this case. Or is it combo media/abrasive, abrasive a given, padding in the form of filler I do not know. Tumbling is bloody complicated. One of few processes that are full of unknowns. Impossible to film or see. All recipes by trial and error. Especially in the polish stages.
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Post by broseph82 on Feb 23, 2015 19:27:15 GMT -5
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quartz
Cave Dweller
breakin' rocks in the hot sun
Member since February 2010
Posts: 3,352
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Post by quartz on Feb 23, 2015 23:47:25 GMT -5
I see one thing I especially like in this, how thin that slab is, don't think I could do one that big in the rotary. Vibe must be very gentle.
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,562
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Post by jamesp on Feb 24, 2015 0:22:04 GMT -5
I see one thing I especially like in this, how thin that slab is, don't think I could do one that big in the rotary. Vibe must be very gentle. Vibe is gentle. Especially with 20 pounds of small garnets. If it was loaded with 50% 1-2 inch rocks that slab would probably be toast. Some dynamic but gentle forces going on with those heavy garnets vibrating at 3000 Hz. If they weighed the same as aluminum the tiny vibrational impacts would have less force. But there is so many acting in all directions it is more like a fluid. Like swimming to the depths in salt water verses a pool of heavy mercury, the mercury would crush you. This is also hard to do, a piece of wavy stained glass 1" X 1/4" after 2 hours in garnets. Notice the SiC 60/90 finish is disappearing on the high area of the wave and the edges.
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tkvancil
fully equipped rock polisher
Member since September 2011
Posts: 1,547
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Post by tkvancil on Feb 24, 2015 9:28:07 GMT -5
Thanks for the heads up jamesp. Will keep watching.
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,562
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Post by jamesp on Feb 24, 2015 10:38:24 GMT -5
Obsidian, various glass, rhyolite, impactite did not enjoy their ride in the semi smooth garnets last night. Looks like fine surface bruising. Garnets a bit too aggressive for them. Could have been the agate mixed with them, but I think it was the garnets. They were running with no thickeners and no padding. Just straight water, not such a good environment for those soft stones. Oh well. Agates and corals improved in polish. No problem with them. They would probably do even better with AO 1000 or 14,000 added.
Today sugar will be added to thicken. Fresh unbruised glass, obsidian, impactite, dallasite will be added.
Those garnets may be softer than most abrasives, but they are a force to be reckoned with.
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SirRoxalot
freely admits to licking rocks
Member since October 2003
Posts: 790
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Post by SirRoxalot on Mar 4, 2015 12:23:16 GMT -5
India pea garnets are great for filler, because you end up with a nice product, unlike ceramic. The perfect size and durability for getting concave surfaces ground. Good clean stuff, too, some fracturing but no pitting whatsoever. Not a whole lot you can do with tiny, deep red, highly polished garnet, but it is pretty. It's good stuff, wish I could get a hundred pounds cheap.
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