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Post by Bob on Aug 19, 2020 11:32:59 GMT -5
In 2014 when I started rotary (all I do) tumbling, I was only using cerium oxide and on everything. Results were fine, but not on some material as would be expected from the literature. I read everything I could find on which polish for which rock type and started experimenting with alum ox, tin ox, and chrom ex. In many cases, it seemed what was happening wasn't what was expected. So then I started comparing just cerium ox and alum ox for agates, jaspers, chalc, etc.--the bulk of what I'm doing.
After much experimentation, I was able to save time (and some money) by switching from cer ox to alum ox. I was able to achieve the same results in 15 days of polish (including burnish) that I was able to achieve in 21 by using alum ox instead of cer ox. And, to my surprise, with most is shine was just a tiny bit better. I say surprise, because alum ox to me after having used cer ox for 2 years is weird stuff. The cer ox slurry is to me a real slurry, with a little bit of thickness to it. But alum ox slurry is no more than diluted milk! It just doesn't look like it could do anything--but it does. Alum ox slurry doesn't even feel slippery to me when I finger it.
It seemed to me that the older the tumbling literature, the more it said to use cer ox as the general polish of choice if you used only one. But recent literature goes alum ox instead. By visiting with an old timer tumbler and researching cerium ox prices I was able to determine that the main reason this happened is because cer ox used to be cheaper than alum ox, but that switched with a vengeance within the last decade. One of my clients does some high tech lapping of glass surfaces much like is done in the telescope mirror labs. He said high quality cer ox is superior to other polishes for such high tech applications on glass, but doubts that rock tumblers need to be using cer ox for much.
He is a high tech ceramics scientist that does mostly work that is classified and he can't tell me everything. But one day, he explained over some beers the materials physics on how a soft material can polish a material far harder than it--which seems pretty impossible when you first think about it. But some polishes are softer than the materials that they polish. At a certain point, he lost me, but boy, did this talk blow my mind. It got pretty fascinating before he lost me. One of these days, I'm going to ask him to do it again and try to have a bit less Guinness this time.
I have also tried chrom ox and tin ox and have kept notes on the results. Parts of what happened frustrate me, and some parts hint at using these at times, but so far results have been inconsistent. I have been thinking hard about a way to test these 4 polishes in some organized way.
What I've done is this. For 2 years now, I've been keeping rocks of similar sizes of many different rocks types. I've kept 4 of each and most are the diameter of a quarter or so. I'm going to set up 4 six lb tumbler barrels, one for each polish. I'm going to spread these rocks in all 4 barrels so each barrel has 1 of each type. Then I'm going to do polish runs and compare the results. It's taken me 2 years to accumulate all these rocks and get them all ready by a 1,000 grit SC run. I have quite a variety, even including nephrite and many other tricky to polish materials. In some cases, I took rocks that I polished years ago and put them back in a 1,000 grit run to kill off the polish on them.
I'm about 1 month from being able to start this experiment. I'm hoping by having it done this way, it will decrease some of the variables. Of course, one weird and potentially undesirable thing about my plan is that rocks types that normally night not ever be polished together will be together in one barrel.
I will photograph these assortments before I begin and share with you if I can ever get the photo upload to work. I will run them for 1 week in dedicated week 1 polish, then photo. Then I will run another week in dedicated week 2 polish, then photo. Then I will burnish for 3 hrs or so and photo.
In a future post soon in this thread I will list out all the rock types I have accumulated. I'm attempting to not duplicate types. For instance, having amethyst, smokey quartz, rose quartz, and crystal quartz would be dumb--they are all just 100% crystal quartz so I will have have only one of them. Some have been very hard to accumulate 4 pieces of of similar condition and size. For instance, chrysoprase, nephrite, lapis, psilomelane, but there are many others.
Originally, I was wanting to tumble all simultaneously, to even eliminate the effects of weather temperature in my garage in Oklahoma. But I have only 3 six lb barrels, so can't do that. But all 4 of the barrels will first have some polish run having completed in them so all will be fastidiously clean. So if I only use one barrel, this test will take about 9 weeks minimum.
Frankly I'm kind of excited about it. What I'm predicting is going to happen is this. I predict that we will be surprised how many rocks types do just fine in alum ox. But I'm hoping that in tin ox and chrome ox there will be some of the rocks which will be distinctly better than those same types in alum ox. That's why I'm looking most forward to discovering. With the cer ox, I'm going to guess that maybe the crystal quartzs might look a little better but I predict may not be able to tell how much compared to alum ox.
Criticism and suggestions are welcome. After 2 years of prep for this, I want do the best I can and not waste my time.
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Post by greig on Aug 19, 2020 12:24:29 GMT -5
It is fun to experiment. Don't forget there are different grades/size of polish. For example, I have stage 3 AO and stage 4 AO in 1500, 3000 and 5 micron. If you are comparing AO to other polishes, you will have to decide which AO you choose.
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Post by HankRocks on Aug 19, 2020 12:46:36 GMT -5
For about 3 years I used Aluminum Oxide for the polish runs in all 3 machines; Model B Rotary, UV-18 Vib, and 20 inch Vib Lap. The results were all very good. About a year ago I came into a lifetime supply of Tin Oxide so I made a switch in all 3 machines. There was no difference in the final polish, or none that I could detect.
I have even made a couple runs using Cerium Oxide and was able to get a good polish. It was the plain Cerium, not the "Super Cerium".
It seems to me that the mix of rocks, both size and type can have as much impact as the polish used. Just emptied a load with too many larger rocks and not enough small and mid-range, it too longer in the Vib to get the polish I had hoped for.
It will be very interesting to see your results.
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lordsorril
freely admits to licking rocks
Member since April 2020
Posts: 926
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Post by lordsorril on Aug 19, 2020 13:01:56 GMT -5
Even if there are many variables involved: I think it is a great idea. There are several types of stones I think that Aluminum Oxide polish does not create as lustrous a shine as I would have hoped. Nephrite and quartz being the foremost in my mind and already mentioned as test material in your original post.  |
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Post by Bob on Aug 19, 2020 14:40:18 GMT -5
The nephrite is only a recent thing for me. Because I just married a Chinese woman, and China is now a big part of my life, I'm around jade in China a lot--mostly jadeite but also nephrite. I also love British Columbia and recently have rockhounded parts of Vanc Island and more or less about 1/3 the way up the Fraser River. I collected a lot of what I would call various nephrite precursor stages up to probably some true nephrite content but none 100% nephrite. The further north I got the more I found. I brought back some pieces too large to fit in my 40lb barrel. I've sandpapered off just small portions to test some of them and oh my God are the internal structures of some of them gorgeous. I'll never forget carrying one piece that weighed I'll estimate about 40lbs about a mile to my vehicle from north of Lillooet. It was too wide to even fit in my daypack, so I carried it over my head with both hands outstretched while also carrying a daypack with about 50lbs of small pieces in it. It was one of the hardest loads I've ever tackled, and at one point I had to give up and drop the dang thing and go back and just get it alone after. After just a few hundred meters I could no longer feel my arms because my shoulders had cut off the nerve supply I guess. Sometimes I get a bit enthusiastic in the field = my twin daughters say "Dad has lost it mentally again."
My rental Subaru was so low to the ground crossing the Can border back into the USA from rocks that I was very afraid it would trigger alarms for suspected hidden compartments and drug running or whatever. When the border guard saw all the rock boxes in the back, he just looked at me like "another one of those rock weirdos".
And I was challenged in The Jade Store in Vancouver to attempt to break a simple bracelet band of high quality nephrite that was only .5" wide by only .25" thick. I'll never forget what happened and how impressed I was with the almost unbelievable strength of the material. So I have bought a few tourist pieces of nephrite and some higher quality pieces on eBay from some guys that mine in BC, just to play with it and satisfy my curiosity about this very strange and strong material.
Trying to saw the stuff was sure fun--NOT. Not even a carbide coated round ceramic cutting blade got very far. I'm not into cabs and slabbing and didn't own any saws. I bought a cheap used small tile saw, but put a good blade on it, and was able to carefully saw some 1" cubes more of less of some good stuff from northern BC, knowing I wanted 4 pieces to use in this polish test. Most of the discussions about nephrite mention forget about rotary tumbling, just do wheel polishing and this or that technique. But I still wanted to try, because at times I'm stubborn...jsut like when I tried to break off a small projection of this nephrite with a 3lb sledge and chisels. Lucky to still have all my teeth. I was like trying to hammer against a solid piece of nylon, a tiny bit of give but nothing happening except loss of control and danger to the idiot trying.
It took 2 months in 60 grit before much started happening at all. Weird stuff--like trying to tumble a piece of hard plastic that just gives a bit but that no abrasive can really grind into. Finally, the corners were gone. Then 80 and 220. I wanted to keep going in 220 until there was none of that internal cracks and flakes that are just under the surface, but I wasn't entirely sure I would ever get rid of them all. So I gave up on that. I Opticonned them, and suddenly the pieces looked pretty darn good. They came out of 600 looking good, and Opticonned again and looked very pretty. They are now out of 1,000 and almost glowing green and are smooth. However, there is a certain "texture" to the feel of them, no doubt due to the internal fibrous structure of this mineral, and something tells me that these aren't going go to come out super in polish. It's just a nagging feeling I have. I have had good luck with Opticon just before the polish run with some rocks that for lack of a better word I want to "tighten up" the surface--lapis, rhodonite, sodalite--and maybe that will help because I will do that too. Will be fun to find out. I invested about $60 in that one piece just to make these 4 cubes to test, and about half of it is left over and the quality of it was well worth and I got a pretty good deal too.
They are so beautiful having come out of 1,000 grit--if I had to stop there it would have been worth it. So far, nephrite is the toughest rotary tumble challenge I've come up against. Garnet, schorl, and vesuvianite maybe next.
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Post by Mel on Aug 22, 2020 9:35:34 GMT -5
This is so incredibly fascinating to me! I use titanium dioxide and I'm finding I can get a polish in 7-10 days on what I tumble - typically the basics; aventurine, quartz, amethyst, jaspers, agates.
I can't wait to see your nephrite results, any results really!. I love the look of nephrite/jadeite, but have only seen highly polished pieces retail, never from a hobbyist.
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Post by Bob on Aug 31, 2020 10:54:49 GMT -5
Well, I'm giving up on Cloudinary. I've put 3-4 hrs into double-checking everything and it still doesn't work. I had planned on photographing the trays showing 4 rocks of each type for this test, because I thought it would be fun to all interested in this to see, but alas can't do that. These trays look kind of neat. So I'm going to post, 10 at a time, the rocks I'm testing and why in case anyone wishes to discuss or contribute thoughts. Any misnomer in the rock name I will put in quotes. I haven't counted, but I speculate there are possibly as many as 100 types. After each I will add the following information:
The Mohs
The polish recommended by the literature (A=alum ox; D=diamond; R=chrome ox; C=cerium ox; T=tin ox; ?=no info avail).
Comments if any
So here goes:
1. Basanite: 7.0; ?. At least I think that's what these black stream rocks are. I buy them on eBay to cushion delicate loads such as when I'm tumbling amethyst.
2. Dalmation stone: 6.5-7.0; T. I love the look of this rock. However, it really never takes a high polish and always has some open pitting to the surface. See Note 1.
3. Epidote: 6.0-7.0; T.
4. Kambaba "jasper"; T. Until I started doing the special treatment (see Note 1) before polish, I wasn't impressed with results which would satiny at best and faded, but that treatment has greatly improved results including making the colors be more contrasting. Still, I'm not satisfied but maybe with 25% of what I tumble.
5. Prehnite: 6.0-6.5; C. I've only been tumbling this material recently and am very fond of it.
6. Psilomelane: 5.0-6.0; T. I have only 1 piece, and need 3 more, so might postpone this test until I get 3 more pieces ready. I've had bad luck with this material having many internal pits and crud open up on me in processing. If anyone has 3 pieces of this about the size of grape and solid I would process and include them and return to you when done.
7. Nephrite: 6.5-7.0, T. I'm very excited about this material. I Opticonned it to tighten the surface, but have never yet taken a piece past 1,000 grit. So I'm double-excited. This might be the only material in this test I have never attempted to polish before.
8. Green tree "agate": 7.0; A. Less than 10% of the material comes out decent to polish; so many pieces have porous areas. I don't think I'm going to buy any more of this.
9. Botswana agate: 7.0; A. This is my representative agate in this test.
10. Onyx: 6.5-7.0; C. I don't have any of this and if anyone has 4 small pieces I would be glad to include them in this test if you send to me. Most of the pieces I have ready for polish are .5 to 1" or so. I've never purchased this, and never found it the field. Most of what is called onyx in this part of the country is really travertine which is a soft form of limestone--way too soft to tumble.
Note 1: I have improved polish results significantly by doing an Opticon treatment just before polish.
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rockstock
spending too much on rocks
Member since April 2019
Posts: 472
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Post by rockstock on Aug 31, 2020 12:35:13 GMT -5
Ditch the cloudinary route and get the tapatalk app for the forum, much easier for uploading. Well... it was even easier, now you can only upload images one at a time instead of a bundle at once. They want you to upgrade or do lots more clicking. See if that works for you.
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Post by Bob on Aug 31, 2020 13:04:22 GMT -5
11. Jadeite: 6.5-7.0; T. Have none, but wish I had some to test.
12. Chrysoprase: 6.5-7.0; A. I actually have two sets of this. One is the cheap stuff that contains only a tiny amount of green commonly sold online. The other much better, almost all the green.
13. Moss "agate": 6.5-7.0; A.
14. Boley "agate": 7.0; A. Almost invariably, there is at least one cruddy soft spot of the brecciated chips, which is irritating.
15. Mookaite: 7.0; A.
16. Novaculite: 7.0; A.
I live close to large quantities of this in certain AR streams. It's brittle and hard to deal with.
17. Porcellanite: 7.0, A. Have only 1 piece of this, and it's too large. Just ordered some rough small pieces so can prepare 4 for this test. It's got an odd surface and I was never able to get a shine, but a pleasing surface non-the-less.
18. Vanport chert: 7.0; A. Duplicative amittedly but had to include this gorgeous stuff in the test.
19. Frogskin jasper: 7.0; A. I have only tumbled a few pieces of this and the finished surface reminds me of Dalmatian stone in never gets a shine or free of tiny pits.
I wonder if this might really be a rhyolite.
20. Picture jasper: 7.0; A. Never have got a true shine on this petrified mud.
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Post by Bob on Aug 31, 2020 15:07:42 GMT -5
21. Spider-woman jasper: 6.5-7.0; A. I find this difficult to polish.
22. Petrified coral: 6.5-7.0; T. Have none, wish I did for this test.
23. Petrified dinosaur bone: 6.5-7.0; special methods to polish apparently. Have none, wish I did for this test.
24. Turritella "agate": 7.0; C.
25. Aventurine: 6.5; T.
26. Quartzite: 7.0; A.
27. Rhodonite: 5.5-6.5, R. Actually have two sets. One is the typical material that is about half manganese oxide, which is very tricky to tumble. The other is all pink and no manganese oxide.
28. Wonderstone: 6.0-7.0; T. I generally don't like the rhyolites because they are not tight enough to get much of a shine.
But I've had decent luck with about 50% of this material.
29. Schorl: 7.0-7.5; T. I have given up on getting 4 decent pieces of this out of pre-polish w/o surface fractures too big to have Opticon help, so it will not be in the test after all.
This is weird stuff.
30. Tigereye (gold): 6.5-7.0; A. I've had pretty good luck with this, but the red and blue varieties don't seen as tight on the fibrous sides and lead to problems more than 50% of the material.
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Post by Bob on Sept 1, 2020 11:42:43 GMT -5
31. Unakite: 6.0-7.0; R.
32. Vesuvianite: 6.0-7.0, C. Unfortunately, I have only 1 piece and it's big. I am trying to buy some more to include in this test. This is one of the hardest rocks I've ever tumbled and it would not surprise me if this piece is Mohs 8.
It took 2 years to get it perfect coming out of 1,000. Then I polished using recommended R. It really messed the piece up! Now it's taken a year trying to clean it up again and still not quite ready.
33. Amazonite: 6.0-6.5; T.
I have never had but 50% max of this come out nice, but still keep trying. See Note 1.
34. Moonstone: 6.0; T. Ditto to 33.
35. Labradorite: 6.0-6.5; T.
Ditto to 33. Took a long time to end up with 4 pieces to test of similar composition that came out nice from 1,000 grit.
36. Oligoclase: 6.0-6.5; T.
Ditto to 33. I know there are several feldspars here that might not perform much differently, but still wanted to test them.
37. Sodalite: 5.5-6.0, A. See Note 1.
38. Indigo gabbro: 4.0-6.0; A. I love the look of this material, and doubt if any will ever polish. Oddly, it comes out of 600 look pretty decent but 1,000 or 1,200 or 1,500 screws it up. I know this makes no sense. See Note 1.
39. Obsidian (Apache tears): 5.0-5.5; C.
40. Glass (manmade): 5.0-5.5; C.
Note 1: I have improved polish results significantly by doing an Opticon treatment just before polish.
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Post by Bob on Sept 1, 2020 16:15:11 GMT -5
41. Hematite: 5.5-6.5; C.
I have two sets. One is pure the kind that polishes to look like chrome. The other is mixes with red iron ore or whatever from iron range in MN.
42. Lapis lazuli (Nili from Afghan): 5.0-6.0, R. This will be the first I've taken all the way to polish. See Note 1.
43. Garnet: 6.5-7.5; R.
I have just one small piece about the size of a pencil eraser and that took 3 years! Wish I had 3 more but don't. Kept trying, but too brittle and kept cracking. Something tells me it's going to come out of this polish test unchanged.
44. Calcite: 3.0; T. Know too soft but including in test anyway. Never have been able to polish this to a shine rotary.
45. Charoite: 5.0-6.0; A.
Only have 1 small piece, but will soon cut it into 4 pieces for this test.
46. Coquina "jasper": 3.0-4.0; R.
I think I've decided to pull this out of test. I dislike this more than like it, and it never takes a shine.
47. Healerite: ?, T. Looks good in rough but the further along one goes the more internal fractures seem there. See Note 1.
Note 1: I have improved polish results significantly by doing an Opticon treatment just before polish.
Looks like that's all those types being used for this test. Wasn't even close to 100 like I thought. Now that I know photo uploads work, will post some pics of these trays containing 4 each of these which are fun to see.
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Post by Bob on Sept 2, 2020 0:08:37 GMT -5
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Post by Bob on Sept 2, 2020 0:14:14 GMT -5
Those are #1-10. I gave some extra shots of the nephrite. The surface is the way a surface prepped with Opticon looks. Before that were very smooth. In one shot you can see the internal "flaking" in this material that is frustrating.
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Post by Bob on Sept 2, 2020 23:57:16 GMT -5
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jamesp
Cave Dweller 
Member since October 2012
Posts: 36,602
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Post by jamesp on Sept 3, 2020 6:00:17 GMT -5
Good luck with wet polish on jade Bob. I have tried many different jades with no success both in rotary and vibe. Apparently it has some type of fibrous composition. The mechanical process of tumbling simply does not work well with some stones regardless of the abrasive used. The felspars are another example of a fairly hard stone that is fussy. You may polish an applied coating but it is doubtful the pure surface of the jade is going to polish. The cab folks have challenges polishing it too, this is usually a bad omen for a tumble polish. Good luck. A familiar sight lol:  |
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Post by Bob on Sept 3, 2020 8:13:40 GMT -5
Yes, that's what I'm expecting. But wanted to try it once anyway. Studying the internal structure of jade is very interesting. Such an interesting material. In China, it's estimated 10,000 people are employed in jade carving polishing industry!
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Post by Bob on Sept 3, 2020 11:16:29 GMT -5
jamesp, in a bizarre coincidence, just this morning before going to work I opened a 6lb barrel that had completed it's first week in alum ox polish. Most of it was typical silicon dioxide material. I forgot that I had thrown in a small piece of nephrite about the size of a watermelon seed. I didn't have time to examine it carefully yet. But it stood out among all the shiny rocks. It was satiny matt, no shine, and felt in my fingers like not much had changed from 1,000 SC grit that came before that.
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Post by Bob on Sept 12, 2020 18:53:43 GMT -5
Here's #21-30. though I have temporarily misplaced the spiderwoman jasper.  |
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Post by Bob on Sept 12, 2020 22:59:08 GMT -5
Here's #31-40.  |
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