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Post by thegrumpybuddha on Apr 6, 2013 15:55:48 GMT -5
Brief backstory: On pretty much every hiking vacation I've taken, I end up bringing a handful of rocks or two as souvenirs. I've got zero knowledge about what I'm taking (other than I like their looks) and after a trip to the Channel Islands/Santa Barbara/the Sequoia National forest, I brought back about 70-80 stones. Upon my return, thoughts turned to what the hell I was going to do with these things, and long story short, I've got my first rock tumbler, set of Moh's picks, plus 2-3 books on types of rocks, identification, etc. Here's a few of my problems: 1) Determining the hardness of these things is a lot trickier than I thought it'd be. It seems like most of the picks leave some sort of mark on the stone -- I guess the gist is that sometimes it's hitting the stone, and sometimes it's the stone hitting it. Perhaps part of the problem is that at least half of the stones are pretty rough. So: Do I throw everything in the tumbler with some rough grit, cross my fingers, and then test whatever's left after it comes out? How bad is it to combine rocks with different hardness? The ones that have a hardness <6 (some of them, I get a smear with the small sample in the Moh's hardness picks supply, so that's helpful, at least) -- can they go in the tumbler? Or will they just disintegrate? 2) On a similar note, I've got at least a couple of stones that barely seem to make a mark on glass (so, hardness <5.5, right?) but that I can't seem to dent with the picks, even the 9. (That stone clearly was towards the lower end, though, given I think I lost 1/3rd of it after one week in the tumbler. It's the odd-shaped all white one.) 3) Identifying these puppies is similarly difficult. I figured out a couple pieces of slate, etc., but most of the stones just confuse the hell out of me. Here are the stones that show the most promise (based on how they look when wet) that have gone through at least a week of phases 1-3 (and most started out somewhat smooth). Only the big honking one in the lower left of the first pick is currently ultra-smooth and almost as shiny when dry as when wet. The others don't seem to have changed much between Step 2 and Step 3. Help?! I will peruse the links in this forum and give it another shot, but I'd like to hear what some pros think (other than "Why are you even bothering with these bland things?!") www.thegrumpybuddha.blogspot.com/p/blog-page_6.html
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Post by susand24224 on Apr 6, 2013 18:21:45 GMT -5
I really like your rocks. The only bland rock is basalt, and even basalt has its positive moments.
You are making this harder than it needs to be. Here are some easier ways to proceed:
1. Throw them all in together, unless you have a few that are *really* soft, i.e., almost crumbly.
2. Leave them together a week or so in 60/90. If the surface feels sort of "rough" on some, take them out--they are likely softer. Since you've got already rounded rocks, you can't use the "this one is rounding much faster" test. Also take out any that look noticeably smaller than when you started, unless they are all noticeably smaller.
3. If any start chipping, get them out as well. I'm not going to terrorize you with the "how brittle" tumbling lecture as this is your first tumble and I don't want to make it more complicated. There is time to fine tune later.
3. If your remaining rocks are not beating each other up, then let them go to polish. The hardest ones will polish, the softer ones will not. No worries, just take the softer ones back to 500 grit (or 1000 if you are using it) run that again, then let them polish with the other softer ones.
4. A word of caution--this may leave you with a bunch of "groups", such as "softer that chipped," "softer that didn't polish," etc. I suggest sandwich bags or some such and a permanent marker so you don't get crazy trying to remember which is which.
Susan
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Post by thegrumpybuddha on Apr 6, 2013 18:50:30 GMT -5
Thanks, Susan -- so, because all of these have gone through the first three steps and survived (though the odd-shaped white one probably lost 1/3rd of it's mass) it's okay/likely that they'll take a polish with Alum. Oxide in step #4? I tried the "rub the stone on a piece of moist leather w/the polish" test and none of these passed it -- that's why I'm concerned. Also -- can you tell me what kind of rocks I'm working with? For instance, which one is the basalt? And what is the black one with white striations? It's the one I'm most concerned about/most want to get a polish on. Looks *awesome* when wet ... Finally: I bought some ceramic filler; do I need to do anything with it before I add it to the Step 4 batch? I don't have enough rocks ready to go to fill the tumbler up but want to get these going ...
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Post by susand24224 on Apr 7, 2013 13:27:43 GMT -5
You don't have any basalt--it's just the rock I get bored with most often. It looks like you have a few quartz rocks (the white one looks like quartz), then a few that are perhaps jasper or flint (I think jasper), one that looks like a possible epidisote, and some others. It is hard to tell from your photos.
Probably *some* of your rocks will polish. Do they feel smooth and even all over? And where did your AO come from? Not all AO is created equal--some hardly polishes at all (the cheaper stuff).
As for the ceramics, I have read here that if you first put them in during the polish stage, they can create problems. I have not tried this myself; I use ceramics throughout most of my loads, not to cushion, but as grit carriers. I would leave them out if your rocks are mostly small--can't tell from the photos.
Give it a whirl--if it doesn't work, rocks are very forgiving, and you can just try it again.
P.S. If you move this thread to the first slot for tumbling, you will likely get more answers than you know what to do with. All of us have our formulas, and many different formulas work.
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Post by thegrumpybuddha on Apr 7, 2013 16:45:47 GMT -5
Thanks -- I think I'll do that this week. Not sure where I got the grit from -- it was a gift from my family, along with the tumbler. Had no idea that there were different qualities of polish -- can I ask you where I should avoid and where I should get it from? Don't seem to be too many places online.
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Post by susand24224 on Apr 7, 2013 17:02:28 GMT -5
The Rockshed (online: Rockshed.com) sells a good AO polish. John at JSGems (a member of this board) also sells a good AO polish and plenty of free advice to go with it. My understanding of AO polish is that it comes in different microns, some works better than others. I bought some cheap AO polish on Ebay once--only once. It polished nothing. I now use it as a pre-polish.
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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 Apr 7, 2013 18:29:44 GMT -5
There are three different types of alumina (AO) used in rock tumbling, they are not just different particle sizes. I'm the kind of person that likes to understand the differences, but none of the AO I've ever seen for sale is labeled as to what kind it is. Usually they don't even indicate their particle size. Also, good polishes are not necessarily composed of all AO, they can contain other ingredients. The only way then to know where to get good polish is to ask someone who has already found it. I too have purchased AO "polish" that was really pre-polish, and I concur with Susan's recommendations.
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Post by thegrumpybuddha on Apr 7, 2013 20:38:49 GMT -5
They have different degrees of smoothness -- the larger triangular shiny one (a little wider than a golf ball, BTW) is ultra-super-smooth, and is shiny when dry already.
The others range from "smooth, but damn, not as smooth as that other one!" to "Er, smooth in parts, layered/a little pitted in other parts" -- for instance, the red/white ones are like this. They look great while wet, but they ain't smooth.
On that -- do you think it's just the nature of the rock? The possibility that they have been in the tumbler with harder rocks? They look great when wet, really want them to polish up if possible ...
Anyway -- given your advice, I think I'll just throw all of these into the Polish stage, with my current AO, figuring that they probably can't get worse, right? (I'll hold back one of the red/white ones, just in case I really need to throw them in with just ceramic and/or softer stones ...)
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Post by helens on Apr 7, 2013 22:55:14 GMT -5
Quick thoughts... if they are already pretty smooth, then polishing is good, but the coarser grits are probably better if they aren't almost shiny yet first. This because it would take a VERY LONG TIME to polish if it's not already shiny, and will only polish the part of the stone with no pits. You want it pretty smooth before going to polish.
You didn't say what kind of tumbler you have... I have a vibe tumbler, and I start with 120/220 grit with 50% ceramic media. That results in almost flawless shine even if you never change the grit!! That's because the vibe breaks the grit down supposedly double the grit per day. I have no way to check that, but it does seem to be true.
If you stuck a semi rough rock into a vibe with 120, and let it run for a week or so without drying out (but NOT wet!!!), so long as it's well buffered from harder rocks (the ceramic), they'll come out almost perfectly polished without ever changing the grit. Changing the grits actually gives you a smoother surface because it takes the rocks backwards a step.
Now that's true for a vibe tumbler, I have no idea how rotary tumblers work. But if you are happy with the overall smoothness, then going to polish is fine. If not, then I'd do 500 before I did polish, just because it would get them all roughly the same polish level so they could more likely finish together.
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Post by thegrumpybuddha on Apr 8, 2013 15:14:35 GMT -5
Hmmm -- the basic rules that came with the (rotary) tumbler said that I know I'm ready for Step #3 when the rocks look shiny when wet. Perhaps that's not accurate ... perhaps they need to keep going, maybe another week in Step #2?
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Post by thegrumpybuddha on Apr 13, 2013 22:42:27 GMT -5
I noticed that the rock I most want to take a polish (the black one in the upper left of the first pic), the hardness seems to be about 7'ish for the black part, but white striations are <5. www.thegrumpybuddha.blogspot.com/p/blog-page_6.html1) Does that give me any clue as to what I'm working with? 2) How does that impact my tumbling strategery? Bad idea to throw it in with the rest of the ~hardness-7 rocks? Should it get its own little batch? For what it's worth, I threw a bunch of rocks in to polish for a week, and one came out quite nice, another, pretty good, the rest, smooth surfaces notwithstanding, they look the same . Going to throw most of them back into Stage 2, I think, go through another wave.
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