chandler3d
off to a rocking start
Member since December 2020
Posts: 8
|
Post by chandler3d on Jun 29, 2022 15:00:11 GMT -5
So I recently finished a batch of lake superior rocks consisting of Unakite, Chert, Jaspers, Quartz, and Agates. After getting them all nicely rounded during several stages in the 60/90 stage I moved them up to 120/220 then onto 500. Between each stage I gave them a brief clean with a toothbrush and water then put them in for a 24 hour tumble in a water and borax solution. I checked them all every time they came out of the tumbler for chips/fractures/breaks you name it. Coming out of the 500 tumble cleaning they all looked fine. Some minor spalls here and cracks and there that have been there since the beginning. Nothing I was worried about, as I've been tumbling for over a year now. Coming out of the polishing grit, however, nearly every stone that came out had unpolished edges (in the best of cases). Many had spalls that cracked and split open, and others had their edges chipped to hell and back. The flat faces of most of the stones look fairly nice and polished, but its grossly overshadowed by the fact that their edges are mangled, and cracks have become massive and rough. I encountered a similar, but not as extreme of an issue, on my last batch of Tiger's Eye, but I chalked that up to just not being used to how Tiger's Eye tumbles. Now I'm starting to think I did something wrong on those too.
My question is: What did I do wrong?
My suspicions are: That I didn't have enough rocks in the barrel, I didn't have a good enough mix of sizes, I didn't put enough water in, or that my Barrel is worn down and does not tumble them correctly anymore. I felt comfortable with the quantity of rocks and distribution of sizes, but I won't rule that out as a possibility because it is technically possible to have ruined the batch.
I tumble in a Lortone 3A that I've had since I started over a year ago. I've kept up with lubricating everything that needs it and I've even replaced the belt once.
Thanks all for any help/feedback!
|
|
stefan
Cave Dweller
Member since January 2005
Posts: 14,113
|
Post by stefan on Jun 29, 2022 16:17:21 GMT -5
OK so remember when we are working on the tumble grind stages we develop a slurry that somewhat cushions the rocks. This prevents the rocks from beating on each other. Polish is a whole new animal. it is thin (like skim milk thin). there is no cushion effect at all. THe polish works into every crack, spall and pit. THe rocks SMash each other (think flint knapping and you get an idea of what happens to spalls and cracks) and the results- as you see- are less than pleasant. SO the solutions are to fill the barrel with more rock (this is where some bags of those dollar store deceptive rocks can come in real handy), thicken the polish (I never tried this but I have heard of everything from sugar, to sawdust, to walnut shell) or add some other type of buffer like plastic pellets (my choice) or ceramic media. I have tumbled for 17 years now and seen my fair share of disappointing batches. I started using plastic pellets in my 500, prepolish and polish stages (as well as my burnish stage) and have not had a singal spall or cracks open up in polish stage. I reuse my pellets (keeping a separate load of pellets for each stage to avoid cross contamination). Hope these ideas give you a good starting point.
|
|
jk49
off to a rocking start
Member since March 2021
Posts: 23
|
Post by jk49 on Jun 29, 2022 17:28:34 GMT -5
As you tumble during the first 2 steps you need to eliminate cracks or pits in the rocks. As the rocks getting smaller using more ceramic or plastic beads. I usually run the pre polish at least 10 days before polishing. The cushioning is especially important if you tumble crystals.
|
|
hoolligan1938
spending too much on rocks
Member since January 2022
Posts: 253
|
Post by hoolligan1938 on Jun 29, 2022 17:41:24 GMT -5
jk49 - You mention the need to eliminate cracks or pits in the first two stages. Can you explain your method for doing this? I've used 330 epoxy and I've tried to use "Art Resin" to fill cracks and pits, but haven't had a lot of luck. Do you apply the fix and then tumble in steps 3, 4 and possibly 5? Do you sand the epoxy on, say a flat lap, before the tumbling, or at any other time? I'm sure an explanation by yourself, or anyone else, would be of much benefit to all of us. If there is a tutorial or some postings that I have not been able to find, please let me know. I'm eager to learn the correct way to do this.
Jim
|
|
|
Post by Bob on Jun 29, 2022 18:02:56 GMT -5
jk49 - You mention the need to eliminate cracks or pits in the first two stages. Can you explain your method for doing this? I've used 330 epoxy and I've tried to use "Art Resin" to fill cracks and pits, but haven't had a lot of luck. Do you apply the fix and then tumble in steps 3, 4 and possibly 5? Do you sand the epoxy on, say a flat lap, before the tumbling, or at any other time? I'm sure an explanation by yourself, or anyone else, would be of much benefit to all of us. If there is a tutorial or some postings that I have not been able to find, please let me know. I'm eager to learn the correct way to do this. Jim It's much easier than all that. You just tumble in the first coarse stage until those defects are gone. If the rock is so lousy that it would take "forever", you need to saw the bad part off, cleave the rock with a chisel, grind out the bad part with a lapidary grinder, or discard the rock. I tumble only to perfection and some rocks take months.
|
|
|
Post by Bob on Jun 29, 2022 18:15:20 GMT -5
...of Unakite, Chert, Jaspers, Quartz, and Agates....Some minor spalls here and cracks and there that have been there since the beginning. Nothing I was worried about, as I've been tumbling for over a year now. Coming out of the polishing grit, however, nearly every stone that came out had unpolished edges (in the best of cases). Many had spalls that cracked and split open, and others had their edges chipped to hell and back. The flat faces of most of the stones look fairly nice and polished, but its grossly overshadowed by the fact that their edges are mangled, and cracks have become massive and rough.... Sometimes I have that happen even with flawless rocks going into polish. Just 2 days ago I finished the first week in tin oxide, a 6 lb barrel, because my big polish comparison test is starting to make this polish look pretty good. The load was half unakite, and the rest was amazonite and a few pieces of obsidian and glass, and 4 of my contest jaspers. Even though my rocks didn't have the flaws you mentioned, the edges of half of the pieces of everything except the jasper came out lousy, though not as bad as yours. I've had this happen before and not understood why. There have been times I've taken the rocks back to 600 or 1,000 for as long as it took to get back ready for polish, tried again, and no problems. This is aggravating but I've learned to live with it. Unakite is touchy, and I do not recommend polishing it with the materials you mentioned. My best luck tumbling it has been with only itself or with other softer rocks such as 100% feldspars (not just partial as is unakite) and others with Mohs of 6 or less. Or, polishing it with about 50% plastic pellets no matter what else is with it. With unakite, amazonite, aventurine, and a few other touchy things, I've also gotten more and more picky about those rocks to continue in the process and discard more and more that have defects and cleavage planes in bad locations. I now Opticon all those just mentioned too. Normally before polish I only fill the barrel 75-80% full. But when tumbling anything that is touchy like unakite and some others, I fill it 80% to 90% full on purpose to slow down the action, at least I think that happens.
|
|
jk49
off to a rocking start
Member since March 2021
Posts: 23
|
Post by jk49 on Jun 29, 2022 21:23:23 GMT -5
I agree with Bob 100%. To get a well polished finished product you need smooth stones without pits and cracks. I would put them in rough or discard. The goal is a perfect shiny finished product. Know when to take them out of rough and through the various fine, extra fine and pre polish. Wash between stages and use cushioning.
|
|
chandler3d
off to a rocking start
Member since December 2020
Posts: 8
|
Post by chandler3d on Jun 29, 2022 22:24:48 GMT -5
I kept this batch in the 60/90 stage for a combined total 3,137 hours. I've had worse condition rocks turn out in better shape than these. I appreciate all the help everyone! I'm gonna send them back in the process and add ceramic media to the later stages. I didn't add any because I thought I had added enough rocks, both small and big into the batch, but I guess not.
|
|
|
Post by Bob on Jun 29, 2022 23:18:24 GMT -5
That's only 4 months. Some take twice that long. Some longer.
|
|
stefan
Cave Dweller
Member since January 2005
Posts: 14,113
|
Post by stefan on Jun 30, 2022 17:14:04 GMT -5
16 weeks in course is nothing for me. I have some pet wood that has been running for 6 months now.
|
|
nursetumbler
Cave Dweller
Member since February 2022
Posts: 981
|
Post by nursetumbler on Jul 1, 2022 8:45:55 GMT -5
I kept this batch in the 60/90 stage for a combined total 3,137 hours. I've had worse condition rocks turn out in better shape than these. I appreciate all the help everyone! I'm gonna send them back in the process and add ceramic media to the later stages. I didn't add any because I thought I had added enough rocks, both small and big into the batch, but I guess not. chandler3dIve been using metamucil in my pre polish and polish stages. I ad about a tsp of SUGAR FREE and a tsp of bleach in my 3 lb barrels and double for my 6#, the bleach is to stop the gas effect of the Metamucil. I've even made up the Metamucil ahead of time and then put it in like you do water in stage 1 and 2. The gel effect cushions like the thicker stage 1 and 2 slurry does. Best part the polish does its job but sticks to the gel so most of the time it just washes out of voids and cracks. I do use ceramics to keep the barrel full enough. You will have to experiment with your water vs Metamucil to get the consistency you want thats why i started making it ahead of time and let it sit while i clean the rocks to make sure its not to gelly.
|
|