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Post by Jugglerguy on Jan 8, 2015 21:01:58 GMT -5
I've been wondering about the difference between silicon carbide and aluminum oxide grit for tumbling. Here's what I use when I tumble: Stage 1: 80 grit silicon carbide (rotary) Stage 2: 220 grit silicon carbide (vibe) Stage 3: 500 grit aluminum oxide (vibe) Stage 4: 1000 grit aluminum oxide (vibe) Stage 5: Rock Shed aluminum oxide polish (vibe) The other day, I was drooling over rollingstone's tumbles in this thread as I do occasionally. I looked over his recipe once again and noticed that he uses 500 silicon carbide instead of aluminum oxide. He's using a rotary all the way through instead of the vibe that I'm using. On the other hand, in Krystee's famous obsidian recipe, she says she uses 500 aluminum oxide in a vibe. The obsidian continues to improve by leaving it in the obsidian for five days. I think the only reason I've always used 500 aluminum oxide is because that's what the Rock Shed sells in their "grit packs", which contain abrasives for all stages. But they also sell silicon carbide in 500, so what's the difference? I've read that silicon carbide breaks down in such a way that there are new, sharp edges exposed and it continues to grind, although with smaller and smaller particles. I get the impression that aluminum oxide does not break down quite the same way, but I'm not sure how it does break down. So here are my questions: What do you use? Is one type of abrasive better for vibes or rotaries?
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jamesp
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Post by jamesp on Jan 8, 2015 21:05:45 GMT -5
I think tkvancil used 500 SiC in vibe on obsidian his last batch. If I remember right, he commented.
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Post by Jugglerguy on Jan 8, 2015 21:15:07 GMT -5
I found the thread, James. Ken's Obsidian BatchLooks like AO beats SC in a vibe for obsidian. Who has other experiences? Is SC better in a vibe for other rocks? Is SC better in a rotary?
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jamesp
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Post by jamesp on Jan 9, 2015 1:40:21 GMT -5
I found the thread, James. Ken's Obsidian BatchLooks like AO beats SC in a vibe for obsidian. Who has other experiences? Is SC better in a vibe for other rocks? Is SC better in a rotary? A grit salesman left a bunch of AO samples for me long ago. I always used SC 220 and 500 on agates in the rotary. Started using AO 220, 400, 500 samples and never noticed a difference. AO rounds and does not crack and splinter like SC. My vibe instructions says to us AO after coarse grind.
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Post by captbob on Jan 9, 2015 1:44:45 GMT -5
My vibe instructions says to us AO after coarse grind. Any idea why?
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jamesp
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Post by jamesp on Jan 9, 2015 2:06:22 GMT -5
Been studying abrasives a lot. SiC is about the fastest cutting grit for the money that you can buy. Because it is sharp, and shatters sharp. it is used as a cutter. AO on the other hand cuts fast at first, then rounds into almost balls. And wears down in a rounder form. Most AO we buy is cheap for 2 reasons, it is a bit of a mix, not 100% 500 particles. Pre rounded graded AO is also very expensive. So perfectly graded AO and shaped AO is costly. The AO 5000 I was searching for is about all precision graded industrial grade AO. Lortone has a 5000, it is really 2000-9000 distributed on a bell curve. In the metals industry AO is the preferred abrasive for fine precision finish, hands down. Including metals harder than quartz. Must be 100 types of AO 500 for industrial applications.
Not much info on AO vs SiC in the rock tumbling world. And even less info on softer abrasives.
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jamesp
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Post by jamesp on Jan 9, 2015 2:10:14 GMT -5
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jamesp
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Post by jamesp on Jan 9, 2015 12:51:42 GMT -5
I've been wondering about the difference between silicon carbide and aluminum oxide grit for tumbling. Here's what I use when I tumble: Stage 1: 80 grit silicon carbide (rotary) Stage 2: 220 grit silicon carbide (vibe) Stage 3: 500 grit aluminum oxide (vibe) Stage 4: 1000 grit aluminum oxide (vibe) Stage 5: Rock Shed aluminum oxide polish (vibe) The other day, I was drooling over rollingstone's tumbles in this thread as I do occasionally. I looked over his recipe once again and noticed that he uses 500 silicon carbide instead of aluminum oxide. He's using a rotary all the way through instead of the vibe that I'm using. On the other hand, in Krystee's famous obsidian recipe, she says she uses 500 aluminum oxide in a vibe. The obsidian continues to improve by leaving it in the obsidian for five days. I think the only reason I've always used 500 aluminum oxide is because that's what the Rock Shed sells in their "grit packs", which contain abrasives for all stages. But they also sell silicon carbide in 500, so what's the difference? I've read that silicon carbide breaks down in such a way that there are new, sharp edges exposed and it continues to grind, although with smaller and smaller particles. I get the impression that aluminum oxide does not break down quite the same way, but I'm not sure how it does break down. So here are my questions: What do you use? Is one type of abrasive better for vibes or rotaries? The second part of this recipe is where I have messed up my obsidian. And that was from not using the vibe for the 220 step. I kept bruising my obsidian in the rotary on the 220 step. Granted, my method may have been wrong. Anyway the bruises carried all the way thru to polish. Been running the bruised OB in the vibe with 220 past few days. Finally, bruises are going away. Eureka. Will run them through at least two 220 runs to be sure, using SiC 220 to cut more rock off to get rid of them. Will never put OB in a rotary again except for coarse grind. captbobPS Vibe broke SiC 220 down very fast, awesome. If I had SiC 120 I would have vibed that before the 220.
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Post by Jugglerguy on Jan 9, 2015 13:36:31 GMT -5
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Post by captbob on Jan 9, 2015 13:46:49 GMT -5
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Post by tntmom on Jan 9, 2015 13:55:41 GMT -5
I haven't tried sic at 500. AO breaks down in 1/2 every 24 hours or so in a vibe. I have done batches of obsidian where I do graded 220 for a day or two. Then I go to 500 ao with a spoonful of borax. The Borax serves as a burnish more than a cushion. I kept the slurry dry enough to look like a thick cream coating the ceramics. After 24 hours the 500 becomes pretty close to 1000. 48 hours 2000. 72 hours 4000 etc. After a few days just spritzing a little bit to keep it moving and the stones are perfectly polished. AO keeps breaking down for up to 5 days. After that it does absolutely nothing in a vibe. If I am doing a presentation then I typically will do a polish run as well but most of the time I just stop after a few days in 500 or whenever I can see my reflection in the stone.
A few years ago, I believe it was Snuffy who posted this, rinsed his stones and put them back in with Borax as a overnight prewash while doing some agates. He got busy and left them alone for a few days "pre-washing". When he took them out the agates had a better polish on them than his typical runs with ao polish!
That got me experimenting with Borax. I believe Borax works as a polish but I do not know what micron it is. I wonder sometimes if when the ao breaks completely down in the vibe, if the borax does a mini polish between each step.
When I have tried obsidian without the borax I never get the same mirror shine results.
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Post by tntmom on Jan 9, 2015 14:04:07 GMT -5
Theoretically, but I haven't tried this.... I have always wondered if I got graded 220 "AO" instead of "SC", if I could do an entire batch without ever rinsing the barrel, just adding 500 and borax to the barrel after a few days when the 220 has completely broken down?
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Post by Drummond Island Rocks on Jan 9, 2015 14:05:43 GMT -5
Back when I first got started and placed my first order with Shawn I had asked him which 500 to go with and he just told me that he recommended the A/O over the SC so thats what I have always used. I have really never questioned that portion of the tumbling process. Just last month I posted this photo of a batch of cabs that had only been tumbled to 500 A/O in the loto for 48 hours. proof is in the pudding. Chuck
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Post by Jugglerguy on Jan 9, 2015 14:17:59 GMT -5
Thanks Krystee and Chuck.
Krystee, I always use either borax or Dreft also. I used to use Dreft, but switched to Borax a year or so ago. I haven't noticed a difference, but I haven't switched back to Dreft either. I'm not unhappy with my shine, but I just wanted to understand the difference in abrasives.
Chuck, I wasn't sure which you used. You definitely get a good shine, but then again, so does rollingstone.
I've never done a batch from start to finish in just one type of tumbler. I bought my Lot-O a couple months after my first rotary, so I've always used a combination of the two. I've been meaning to try tumbling with just one tumbler. A couple days ago, I started a batch in my Lot-O without roughing in a rotary. It's a fun little experiment. I'm using 120/220 SC and doing clean outs every 24 hours. I'm going to try Rollingstone's method in just a rotary next. That's what got me wondering if I should be using 500 SC in the rotary.
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jamesp
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Post by jamesp on Jan 9, 2015 14:41:35 GMT -5
Powdered detergent: The original Bon Ami formula was developed in 1886 by the J.T. Robertson Soap Company as a gentler alternative to quartz-based scouring powders available on store shelves. In those days, scouring powder was made from tallow and finely ground quartz. When quartz was mined, it was entwined with a mineral called feldspar, and the two had to be separated by hand. The feldspar was discarded until Robertson discovered that this soft mineral could be combined with soap to create a less-abrasive product that would clean without scratching, resulting in the Bon Ami product. Toothpaste: Abrasives constitute at least 50% of a typical toothpaste. These insoluble particles help remove plaque from the teeth. The removal of plaque and calculus helps minimize cavities and periodontal disease.[citation needed] Representative abrasives include particles of aluminum hydroxide (Al(OH)3), calcium carbonate (CaCO3), various calcium hydrogen phosphates, various silicas and zeolites, and hydroxyapatite (Ca5(PO4)3OH). Kaolin clay has AO in it. A filler for many products: The chemical formula for kaolinite as used in mineralogy is Al2Si2O5(OH)4,[3] however, in ceramics applications the formula is typically written in terms of oxides, thus the formula for kaolinite is Al2O3·2SiO2·2H2O.[10] Cement chemist notation is even more terse: AS2H2, with the oxides represented as A = Al2O3, S = SiO2, H = H2O. This clay, also known as China Clay, White Clay, China White clay, Chalk and White Dirt, is chemically composed of Kaolinite (97%), silicon oxide, aluminum oxide, iron oxide and titanium oxide. Benefits of kaolin clay in soap,and other bath products include being very mild, improving blood circulation to the skin, exfoliating and cleansing. This white clay also detoxifies at the skin level without drying the skin, unlike other clays. Its gentleness makes it a great additive in products for dry or sensitive skin. Some of the products that this gentle white clay can be found is in facial products, natural deodorants, poultices, scrubs, mineral makeup, and body powders. Diatomaceous earth: The oldest use of diatomite is as a very mild abrasive and, for this purpose, it has been used both in toothpaste and in metal polishes, as well as in some facial scrubs.
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Post by Toad on Jan 9, 2015 14:51:23 GMT -5
I never use AO because of the whole SiC breaking down with sharp edges thing. I get great results with agates, pet wood and wonderstone - but haven't tried obsidian yet. Here's the recipe I'll be using for obsidian this year:
60/90 SiC - until done (recharge weekly) 220 SiC - for 2 weeks (no recharge) 600 SiC - for 2 weeks (no recharge) 1200 SiC - for 2 weeks (no recharge) TiO - for two weeks
All stages in a rotary. Nothing against AO, just didn't want to spend the money on another grit when I already had a system in place. I already know what results some of you get with the AO, I'll see if I can match it with the SiC.
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jamesp
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Post by jamesp on Jan 9, 2015 15:01:12 GMT -5
39don starts with SiC 90 in his Viking vibe, and then straight to cerium oxide polish--on agate. No other steps.
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Post by johnjsgems on Jan 9, 2015 15:40:13 GMT -5
Can't remember which one but someone sells diatomaceous earth as a lapidary polish. Years ago a guy demonstrating sphere making at a show was complaining he drove over 100 miles to buy some of this "polish" at a pretty high cost. I told him it was DE and he laughed at me. He called me when he got home after checking the 50 lb. bag he had for his pool filter. Same stuff. I love it when I'm right. I was going to market some as a pre polish and gave samples to a couple of guys that tumbled a lot. Both the white and the brown stuff. One guy said it worked great and the other said maybe as a pre polish but he wasn't impressed. I think it was the brown stuff. I kind of lost interest in selling it but it may be worth a try. The stuff is cheap.
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jamesp
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Post by jamesp on Jan 9, 2015 16:50:54 GMT -5
The brown diatomaceous earth is usually AG grade, crushed and sifted to a flour consistency. Probably run through a 320 mesh lime screen. The white is likely filter grade DE and likely coarser. It is opaline silica and about mohs 6.(as far as they can tell, it is microscopic, but should be able to be tested w/abrasion test on known material. The brown DM broke down quickly to what looks like a polish on the high areas of these obsidians.(30 hours) left before DM, middle @ 20 hours, right at 35 hours(or less). It is too fine to remove the 500 grit pits, but it did impart somewhat of a polish on the high spots. And quick, thought that was hurdle. If the white is coarse enough, it may remove the 500 grit finish and continue to break down to a semi polish/polish, perhaps quickly. By the same token, it may be too soft and break down before it has a chance to remove the 500 finish. On the other hand, if diamond was used, it may take a long time to break down, if it ever does, so softer grit should respond well to softer rocks. But it seems that it has to be the right ratio of softness to the rock being tumbled. The advantage DM has is that is very porous and fragile, due to micro pores running through it. A unique characteristic of any abrasive, and should break down quickly. The disadvantage is that it may be like SiC and have many sharp edges, and not give a fine polish, but prep for a polish. Tripoli is made out of DM. Just coated in waxy binder. Diatoms(miniature space monsters):
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Post by connrock on Jan 10, 2015 10:57:57 GMT -5
I don't know weather sc or ao works better in a Lot-O but what I do know,,,,as many of us do,,,,is that if you leave a load running long enough with only a squirt of water to keep it loos enough,,,the rocks will shine without a polish stage. I've posted this photo so may times here that some of you may be tired of seeing it but it does prove that a polish stage isn't necessary,,,, Left is Montana Agate and right is Brazillian Agate,,, These were left in Tripoli and it's been so long I can't really remember how long but I would say about 2-3 days,,, Kristee said something about starting out with graded 220 sc and just let it run and I really think it would work.I think the key is to have good solid material that has been roughed in a rotary so that there are NO flaws. connrock
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