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Post by Bob on Sept 24, 2020 10:49:06 GMT -5
I'm attempting another run at glass and obsidian after trying it once 3 years ago and failing in polish. So I've been building up more and more and almost have enough for a 12 lb barrel in 600. I've had good luck also tumbling pieces of delicate material with it, such as small pieces of aventurine, amethyst, moonstone, etc. though I make sure those are all well rounded first.
I didn't have enough for a full 220 load, but I needed to go ahead anyway to get a bit more for that 600 batch, so I did something I normally avoid, which is to go forward with less than a 50% normal load. To take up space, I used far more plastic pellets than ever before. Probably 60-70% of the load was those. And, I filled the barrel 80-85% or so which I've learned over time helps with delicate stuff and has been working well for obsidian and glass from the very beginning of rough grind. Normally with this material, I would have at least 30-50% plastic pellet cushioning anyway.
Anyway, I opened it after normal 7 days last night. There is no damage, but what's really weird is the amount of grit left was shocking. After standing the 12 lb barrel on its end, there must have been maybe 3/8" of grit that settled to the bottom quickly. Normally it sort of disappears and just becomes grey muck that is as we know partially rock dust and super fine grit. But I could immediately tell by look and feel this was almost all grit, even though it felt finer than 220 as might be expected from a week of grinding. But never even once in 6 years have I see this much grit left! I had even used less than my normal 1 cup of grit for this size barrel because the load of rocks to be ground was less.
Does anyone know what the heck happened?
Does rock dust from obsidian and glass sort of not exist--does it disappear?
The obsidian and glass and other things, do look like they got worked in 220 okay and are ready for 600, but I can also tell not as much happened as would be expected due to some fine lines still being there and needing a 220 run again. That's not bothering me too much.
I'm wondering if having the load be more than 50% plastic pellets, which I had never done before, is the culprit? Does something weird happen in such circumstances? I also realize that glass and obsidian are light in weight, and the whole mess may have just sort of been floating around in there. The 80% fill to protect may have worked against me.
Any ideas suggestions are welcome.
Sometimes there are one off things that happen as we know. If this happens again, I'm thinking about not using plastic pellets are cushioning but instead to use half worn down large ceramic pieces which I also have.
Just wrapping up writing this, something suddenly dawned on me. When I tested plastic pellets years ago in 50, 80, 220, 600, and 1,000, they worked fine in 220 and finer, but in larger grits nothing happened in a week. The grit would be still there and the rocks unground and so was a waste, so since then I never used plastic pellets before 220. But, that was all with misc. material and not with obsidian or glass. Maybe with obs and glass plastic pellets also detract from anything happening in 220.
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lordsorril
freely admits to licking rocks
Member since April 2020
Posts: 896
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Post by lordsorril on Sept 24, 2020 10:53:44 GMT -5
I'm wondering if having the load be more than 50% plastic pellets, which I had never done before, is the culprit? You got it! Plastic pellets strike again! I decrease my grit ratio by 50% at any stage if I'm using plastic pellets as cushioning. |
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Post by Bob on Sept 24, 2020 11:04:37 GMT -5
What? Do you mean you use less grit? Do you mean you just assume less work will get done?
If that's what you mean, maybe I should just let the batch run 2 weeks instead of my normal 1 week, because it might take 2 weeks or even longer to get the usual amount of work done.
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lordsorril
freely admits to licking rocks
Member since April 2020
Posts: 896
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Post by lordsorril on Sept 24, 2020 11:12:07 GMT -5
What? Do you mean you use less grit? Do you mean you just assume less work will get done? If that's what you mean, maybe I should just let the batch run 2 weeks instead of my normal 1 week, because it might take 2 weeks or even longer to get the usual amount of work done. Yes, I check my barrels weekly, so I use 50% less grit with plastic pellets because the grit won't break down as fast (and I don't like wasting grit). I am uncertain what the outcome would be if you kept it running longer than 1 week--it is possible that the slurry generated over time may slow down the action even further... |
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Post by Bob on Sept 24, 2020 11:22:21 GMT -5
Okay, I'm going to test this. I will have another 12 lb batch of obs/glass in a month or so, and I will just test it for a 2 week run when it gets to 220.
FYI, my tumblers are in my garage. In the hot time of the year, my 40lb is done in only 4 days! In winter, 5-6 days. My 12 lb barrels are usually done in a week, but in winter up to 10 days. Sometimes I forget to lengthen the period as summer turns onto fall like right now, and when I open the barrel I can often immediately see from the feel and look of the slurry on top that there is grit left in there. So I wash the lid liner, clean the groove, put it back to run often a full week and it really doesn't annoy me. I actually never open barrels to inspect, unless I hear something not quite right.
Two times this year I have heard something not right and found out I had forgot to add water! Bet you've never been that dumb. Last week, I came within a hairs breath of something far worse, not using the lid liner on a 12lb barrel! I tried to screw on the nut and was wondering why there was nothing to screw it to. Granted I was thinking of something else. What really scares me is I was so distracted that I nearly carried it over to put on the tumbler within the nut off thinking oh well, something not right this time but will probably still be okay. That load would have gushed out all over me the moment I turned the barrel sideways.
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lordsorril
freely admits to licking rocks
Member since April 2020
Posts: 896
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Post by lordsorril on Sept 24, 2020 12:26:41 GMT -5
Bet you've never been that dumb. Everyone has their 'moments'... When I was breaking up some feldspar I said to myself 'Wow, this piece looks really sharp-I wonder how sharp it is?' and I poked my calloused thumb to test it and it went straight in about 1/4" with zero resistance. Answer: Very sharp... |
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Post by Bob on Sept 24, 2020 13:55:02 GMT -5
Yea that was smart. It took a year but I finally got DUMB ENOUGH enough to grab the largest tegu I had ever seen in an attempt to manhandle it. Took a month to work out the plan and another month to work up the courage. Unfortunately for me, the tegu must have been watching me the whole time and working out his plan too. The enclosure was the size of a small house. Thank God there were no witnesses. It would be a hard call as to who won. I managed to save both eyes and not have to go to the doctor--barely. His ego was hurt because at one point I got him airborne. In case you are ever dumb enough to even think of doing this: #1 don't do it with one that was sitting under a heat lamp with all its bulging muscles ready to go and just lying in wait for a human to try something, and #2, wear eye protection goggles as that tail in action is about like the Mother Alien. I promise you that with herps I am 10x dumber than you and lucky to have survived past age 30. What you did with that feldspar is EXACTLY what I would done. Unfortunately for you, maybe we have a common ancestor. Be careful when you are slicing that apple open for breakfast.
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Post by greig on Sept 24, 2020 15:34:13 GMT -5
I have never run so much media in a run, but my first thought is with little rock and lost of plastic that you had too much water and the pellets floated...so grit wasn't effectively rubbing on your rocks. As for doing dumb things, I think I have done them all and am now working on doing them all twice.
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Post by Bob on Sept 24, 2020 15:49:12 GMT -5
Well, greig, you are apparently a survivor! By the way, yea Canada!!! I'm a backpacker and love your country, your people, and especially your parks, and really like Killarney and Algonquin PPs not far from you and REALLY really like Pukaskwa NP a ways west of you. Have never explored the shoreline of Lake Ontario. Does it have nice rocks like Lake Superior? Like your theory about the water and pellets and grit.
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Post by parfive on Sept 24, 2020 17:23:25 GMT -5
As for doing dumb things, I think I have done them all and am now working on doing them all twice. Reminds of comment I saw recently, by a Bob Loblaw . . .
Back when I was an active pilot, the Canadian Aviation Safety Letter had a masthead motto: “Learn from the mistakes of others. You won’t live long enough to make them all yourself.”
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Post by Bob on Oct 28, 2020 14:30:26 GMT -5
Well, I want to post an update on this obsidian and manmade glass run in case anyone has comments. I waited until I had more in a 12lb barrel load to continue. So instead of over half plastic pellets, maybe 40-50%. There are also 2-3 pieces of amethyst in there too. The rest is 2/3 obsidian (mahog, Apache tears, misc. black and rainbow). 220 finished fine. 600 fine. 1,000 fine. So, finally after 3 years I'm ready to try this tricky material in polish again. One week in cerium oxide. Wasn't as shiny as I hoped, but wasn't a disaster either. Another week in cer ox polish reserved for only use in week 2. Got better, but something not right. Not near the shine as should be. Didn't bother examining under hand lens, but did 12 hours burnish. I could tell immediately before drying off rocks where much shiner. But alas, something still not right as a bit of a matt not real shiny. The mahog obsidian almost shiny enough. All if it looks fantastic when wet too.
So, I have now got it running a full week in burnish (full bar of Ivory soap) to see if that makes any difference.
I was as fastidious as ever with cleanliness. Except for this, I've rarely had batches in polish not turn out perfect for over 2 years, though that was with chert, agates, jaspers, etc.
I will know in 5 more days if this long burnish run will help. I'm not very optimistic. One thing I thought about trying is running a full 10 days in polish run 1, and another full 10 days in polish run 2, instead of a week each. Does anyone have any other ideas as to what might have gone wrong?
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lordsorril
freely admits to licking rocks
Member since April 2020
Posts: 896
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Post by lordsorril on Oct 28, 2020 16:54:17 GMT -5
What size pieces are you using Bob? Is the matte polish on some pieces and not others? Do you think the quality of the material could be a factor? Sometimes material looks promising...but...not so much...   |
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Post by Bob on Oct 28, 2020 21:34:56 GMT -5
The pic on left looks like a slab. What is the one on the right?
I will photo the batch after this burnish run. There is wide variety of sizes.
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lordsorril
freely admits to licking rocks
Member since April 2020
Posts: 896
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Post by lordsorril on Oct 29, 2020 5:01:42 GMT -5
The pic on left looks like a slab. What is the one on the right? The picture on the left is one angle. The picture on the right is another. It is actually a concrete brick with a piece of plastic glued to it, and a piece of paper that looks like agate sandwiched between another piece of plastic affixed to the top. |
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EricD
Cave Dweller 
High in the Mountains
Member since November 2019
Posts: 1,142
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Post by EricD on Oct 29, 2020 7:18:46 GMT -5
Well, I want to post an update on this obsidian and manmade glass run in case anyone has comments. I waited until I had more in a 12lb barrel load to continue. So instead of over half plastic pellets, maybe 40-50%. There are also 2-3 pieces of amethyst in there too. The rest is 2/3 obsidian (mahog, Apache tears, misc. black and rainbow). 220 finished fine. 600 fine. 1,000 fine. So, finally after 3 years I'm ready to try this tricky material in polish again. One week in cerium oxide. Wasn't as shiny as I hoped, but wasn't a disaster either. Another week in cer ox polish reserved for only use in week 2. Got better, but something not right. Not near the shine as should be. Didn't bother examining under hand lens, but did 12 hours burnish. I could tell immediately before drying off rocks where much shiner. But alas, something still not right as a bit of a matt not real shiny. The mahog obsidian almost shiny enough. All if it looks fantastic when wet too. So, I have now got it running a full week in burnish (full bar of Ivory soap) to see if that makes any difference. I was as fastidious as ever with cleanliness. Except for this, I've rarely had batches in polish not turn out perfect for over 2 years, though that was with chert, agates, jaspers, etc. I will know in 5 more days if this long burnish run will help. I'm not very optimistic. One thing I thought about trying is running a full 10 days in polish run 1, and another full 10 days in polish run 2, instead of a week each. Does anyone have any other ideas as to what might have gone wrong? The only time I ever tumbled any obsidian it would not take a good shine until I removed everything but the obsidian and ceramic media. One tiny piece of white quartz I overlooked in the ceramic left tiny scratches on every piece of obsidian. (Done in a Lot-O vibe)
The ceramic I used had previously been polished in another batch.
Once I found that quartz, I ended up with a liquid shine. Pretty annoying experience altogether.
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gatorflash1
spending too much on rocks
Active in Delaware Mineralogical Society, Cabchon Grinding and Polishing, 2 Thumlers B's and a UV-18
Member since October 2018
Posts: 375
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Post by gatorflash1 on Oct 29, 2020 8:58:30 GMT -5
CD - Great news, at least you found that little devil but I'm surprised the quartz was in such rough shape to scratch the rest. I wonder if others have had problems with quartz in the mix I am usually sticking to agate, jasper, etc. so any quartz in the mix is never a problem because the other higher mohs stones beat it up pretty good..
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Post by Bob on Oct 29, 2020 11:05:54 GMT -5
Well, Eric, I do admit was wondering if those two pieces of amethyst could be the explanation. They are super smooth but of course 1.5-2.0 Mohs harder than the obs and glass. I was even wondering if man-made glass plus obsidian both in same batch could be the explanation. Some of the obsidian I want to tumble are fist-sized, and I'm trying to nail the process in order to get ready for those next year. I was hoping man-made glass could be used in place of more obs to complete the load.
The amethyst and smoky quartz and rock crystal have been tumbling great together with glass and obs up to polish. At least they look like they get along well. But there is always the possibility that I'm wrong and coming out of pre-polish (1,000 SC) something wasn't right that I couldn't see with bare eyes.
If I have to tumble only obsidian with itself, and only man-made glass with itself, it won't be much fun for me. But if that's what it takes, I'll do it. My smallest barrel is 6lb. And if a piece of material is lemon/fist size, it has to go in the 12lb barrel for me to feel comfortable with the mix and the barrel volume and to prevent potential jamming between the bottom and the lid. So, if I can only do one material I either have to wait until I have enough of it to polish to fill a 12lb barrel, or have a whole lot of pellet filler, or stop tumbling larger pieces which I don't want to do.
Those kind of logistics is what makes doing the large rocks a pain at times. I've got my largest ever piece of chert in 20lb barrel pre-polish now. It's almost 7" long. So, I've got all these other agates, jaspers, cherts, etc. to go with it in a polish run soon of 20lb. That will be only the 2nd time ever I've done polish in the 20lb barrel, which takes a good bit of polish to do. I've purchased some pieces of obsidian that are grapefruit size, and at the rate I'm learning it's going to be years before I have the courage and knowledge to properly deal with them.
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lordsorril
freely admits to licking rocks
Member since April 2020
Posts: 896
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Post by lordsorril on Oct 29, 2020 11:53:56 GMT -5
or stop tumbling larger pieces which I don't want to do. Amen brother. Keep those big chunks of obsidian spinning. I've got one going right now. Going to be a while before I have to deal with polish though.   |
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EricD
Cave Dweller
High in the Mountains
Member since November 2019
Posts: 1,142
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Post by EricD on Oct 29, 2020 12:01:48 GMT -5
gatorflash1 Bob that little piece of quartz that looked almost exactly like a ceramic cylinder had no fractures or chips, absolutely no imperfections that I could find. The polish was almost acceptable, you could almost not see the tiny, and I mean microscopic, scratches, but the shine wasn't acceptable to me. 3 days after I removed it I had a liquid shine and could see no scratches at all. I don't know why the harder ceramic didn't do similar to the obsidian as what the little quartz did. Since then, any time I attempt to polish obsidian, I use only previously polished ceramic/obsidian pebbles, even if I'm only polishing one piece of obsidian. I only use the ceramic and obsidian pebbles for AO500 and AO polish. My filler-to-target-rock ratio is sometimes as low as 75:25 and as high as 99:1 (one cab/stone in a sea of media). No trouble getting a liquid shine since. This could be completely worthless information to a rotary-only tumbler since I use a vibe for polishing, but I can't say for sure.
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Post by Bob on Oct 29, 2020 13:29:50 GMT -5
One other variable is I recycle polish. The polish I've been using is 3 years old and still works great. I'm fastidious about it and won't even open a container of polish without brushing off my hair and even under a lamp that has dust on the lampshade. When I open the polish container, I only have it open for as few as seconds as possible. I can see no difference in polish results from new polish vs 3 yr old polish, at least with cerium ox and alum oxide.
But, what if ob is best polished with only new and previously unused polish? Gosh, I hope not. Or what if polish used for obs can be used again, but obs will only polish well with polish that if previously used was only used with obs? Does anyone reading this have opinions on those two questions?
lordsorril, that's bigger than any one I've tacked so far!
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