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Post by Lazy Perfectionist on Aug 16, 2023 12:00:38 GMT -5
I've been tumbling non-stop ever since we came home with two five-gallon buckets of obsidian 10 months ago. I'm running two rotary tumblers and three vibratory (thanks to a loan from a generous neighbor), all different models.
Here are my questions (for now):
1) What is the potential problem with cheaper grits?
2) When using the vibratory tumblers, is grit still working even once the rocks are covered in a thick coating (presumably rock particles)? This typically happens within 1-2 days with the 500 SiC. Should I add more grit or wash-out?
3) What effect does the size of the media have? Can small stuff lead to pitting?
4) The advice I've seen is that you should have a mix of large and small media, however it seems like the bigger rocks all congregate on side and don't mix with the media and smaller rocks.
5) Lately it seems like the AO polish isn't working as well. The shine seems great (sharp reflection), but it looks like some sort of residue is visible when examined under very bright light. It doesn't improve with longer in the tumbler. Ideas?
Here's what I've learned (so far):
After the initial rotary run to smooth the rocks, any chips and cracks, no matter how tiny, will persist and sometimes get worse. I have to grind them completely away before progressing. They are often much deeper than they appear. Also, I suspect that any sharp edges will damage other rocks in the vibratory tumbler. These are not surface scratches from the flat lap - those smooth out fine in the tumbler.
I've had a heck of a time trying to polish stones on a flat vibe because the higher grit discs (>800) would suddenly start creating deep scratches. After looking under a microscope, I determined that tiny obsidian chips were get embedded in the disk. I think my mistakes were too much pressure as I ground, and continuing to higher grits with pieces that weren't flawless due to tiny cracks (see above) or ash pockets.
Using small agates (aquarium rock), broken plates, and boring pieces of obsidian is cheaper than ceramic media, however flat pieces don't work very well in the vibratory (they just climb the sides).
To prevent damage to delicate obsidian, NO big pieces (they will have to be done independently)! Also, I will start the tumbler with just the media, grit and water and once it's running tumbling gently enough, then I add the obsidian.
You have to dry the obsidian to check whether it's ready to advance to the next stage, otherwise you can't see those tiny flaws. I find that looking at them in direct sun let's me see any microscopic pits (they catch the light and sparkle).
Different types of obsidian have different hardness and other qualities. Some with many layers of impurities can be softer, sheen caused by tiny bubbles may not polish well if the bubbles are at the surface (also causes chipping). Maybe others had some chemical reaction between impurities and borax.
It's awesome having a husband able/willing to repair equipment!
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Post by chris1956 on Aug 16, 2023 12:21:00 GMT -5
#3 - Hopefully someone has some experience with this. I have wondered the same thing. I bought some really small ceramics thinking that they would get in the smaller imperfections and I wouldn't have to grind those down separately. Didn't seem to work and all the small stuff tends to break apart to the point it is almost like sand particles. Eventually, your larger material will get worn down to different sizes anyway.
#5 - Do you burnish with soap or borax after the AO polish? I would try that if you don't or maybe make two runs with soap or borax and see if that helps.
I will leave the rest to the real experts.
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Post by velodromed on Aug 17, 2023 10:28:34 GMT -5
I've been tumbling non-stop ever since we came home with two five-gallon buckets of obsidian 10 months ago. I'm running two rotary tumblers and three vibratory (thanks to a loan from a generous neighbor), all different models.
Here are my questions (for now):
1) What is the potential problem with cheaper grits?
2) When using the vibratory tumblers, is grit still working even once the rocks are covered in a thick coating (presumably rock particles)? This typically happens within 1-2 days with the 500 SiC. Should I add more grit or wash-out?
3) What effect does the size of the media have? Can small stuff lead to pitting?
4) The advice I've seen is that you should have a mix of large and small media, however it seems like the bigger rocks all congregate on side and don't mix with the media and smaller rocks.
5) Lately it seems like the AO polish isn't working as well. The shine seems great (sharp reflection), but it looks like some sort of residue is visible when examined under very bright light. It doesn't improve with longer in the tumbler. Ideas?
Here's what I've learned (so far):
After the initial rotary run to smooth the rocks, any chips and cracks, no matter how tiny, will persist and sometimes get worse. I have to grind them completely away before progressing. They are often much deeper than they appear. Also, I suspect that any sharp edges will damage other rocks in the vibratory tumbler. These are not surface scratches from the flat lap - those smooth out fine in the tumbler.
I've had a heck of a time trying to polish stones on a flat vibe because the higher grit discs (>800) would suddenly start creating deep scratches. After looking under a microscope, I determined that tiny obsidian chips were get embedded in the disk. I think my mistakes were too much pressure as I ground, and continuing to higher grits with pieces that weren't flawless due to tiny cracks (see above) or ash pockets.
Using small agates (aquarium rock), broken plates, and boring pieces of obsidian is cheaper than ceramic media, however flat pieces don't work very well in the vibratory (they just climb the sides).
To prevent damage to delicate obsidian, NO big pieces (they will have to be done independently)! Also, I will start the tumbler with just the media, grit and water and once it's running tumbling gently enough, then I add the obsidian.
You have to dry the obsidian to check whether it's ready to advance to the next stage, otherwise you can't see those tiny flaws. I find that looking at them in direct sun let's me see any microscopic pits (they catch the light and sparkle).
Different types of obsidian have different hardness and other qualities. Some with many layers of impurities can be softer, sheen caused by tiny bubbles may not polish well if the bubbles are at the surface (also causes chipping). Maybe others had some chemical reaction between impurities and borax.
It's awesome having a husband able/willing to repair equipment!
I just have a little bit to add. First off, cheap grits. Stay away from them. I did a lot of experimenting with SiC grits I got off of Amazon and had lots of issues, including ugly, staining to my raytech 5 vibe bowls and so forth. It was a completely different story when I got quality grits from Kingsley north, and the rock shed. So I know when it comes to vibe tumblers, grit quality matters. I’m now using up all of the crap grip in my rotary tumblers where I don’t notice issues. As for polish, same thing. I didn’t start getting that beautiful mirror shine until I got quality micro AO polish. So now I use all the other polishes I had bought as pre-polish. I have some rocks I just pulled from 1500 AO Amazon polish after 2 days in the vibe. Now I’m going to run them for three or four days in micro AO, and even though these look shiny and pretty now, they will look better in a couple days. Maybe not by photo, but to the naked eye they definitely will. One thing to keep in mind when you hit the polish stage is AO polish will break down from 1200 to 1000s depending upon how long you run it. So when you pull the rocks from pre-polish and put them in polish, you’re actually taking a step back for a bit. If you don’t let them run long enough, you’ll get that cloudy look. Regarding all of your rocks loading to one side and the media and smaller rocks are on the other. I had that issue and found out that it is directly related to how much moisture is in the bowl and also how loaded it is. So if things start gravitating towards one side, first I will pull the lid and let it dry out some. Next, if that doesn’t take care of the issue, I will pull out some of the media. If I’m still having problems, I pull out some of the rocks themselves until it all comes together. I have a Raytech 5 by the way. I have found that I prefer the medium size ceramics for the vibe. I do not use ceramics in rotary tumblers, I use other small rocks. Even in my vibe for stages two and three and I have a mix of roundish river pebble agate and ceramics. I only use ‘just ceramics’ in the polish stage in my vibratory Tumbler. I’ve never noticed that new rocks will damage old rocks, unless you are putting drastically different hardness rocks together or tumbling delecate rocks. I never tried to tumble obsidian, I imagine it’s a challenge. I am constantly pulling rocks from my tumblers as they are ready to move to the next stage and putting in fresh ones. No issues so far, but I do a lot of petrified wood, agate and jaspers, which are all fairly tough rocks. I think that most of the cracks and issues that appear in rocks are already there and uncovered through the process of tumbling. Good luck bud!
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Post by Lazy Perfectionist on Aug 17, 2023 11:38:59 GMT -5
One more question - is 500 SiC more aggressive than 500 AO?
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Post by velodromed on Aug 17, 2023 11:57:32 GMT -5
One more question - is 500 SiC more aggressive than 500 AO? Yup. SiC is sharp and stays sharp as it breaks down to nothing eventually. It’s definitely more aggressive. AO is more rounded and breaks down finer and finer but still continues to work. After stage 1, each stage SiC grit is really meant to just remove the scratches from the previous stage . Stage 1 is really the only stage that ‘shapes’ the rock. Then the polish does it’s thing somehow, as long as the rock was properly prepped by previous grits that is. At least this is how I understand it.
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Post by velodromed on Aug 18, 2023 3:08:28 GMT -5
One more question - is 500 SiC more aggressive than 500 AO? Oh, forgot your question on slurry covered rocks. Yes it absolutely helps the grit work to have a good slurry that covers the rocks. There’s also something else that goes on by the simple action of the rock sliding against each other through the slurry, but I forget what it’s called. Can the slurry be to thick? I think so. I try to keep mine a medium consistency in the tumblers. I even recycle half the slurry each change out in course stages, as long as it’s not super stinky. In my vibe I try to keep it a lighter consistency because the action is better.
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RockyBeach
spending too much on rocks
Member since July 2023
Posts: 319
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Post by RockyBeach on Sept 3, 2023 10:49:25 GMT -5
Always happy to find questions I was going to ask AND answers to those questions !
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