lancemountain
starting to spend too much on rocks
Member since March 2017
Posts: 214
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Post by lancemountain on May 26, 2019 9:06:12 GMT -5
Hello! I started a batch of labrodolite and everything was going great- 2.5 ish weeks in a lortone 33b rough They were all shaped and smooth with no cavities, scratches or chipping. I moved them to my Lot-O and did 24 hours in 1 TBL 120 and borax. They came out about as good as I could have expected. I put them into the 500 stage and I left them in for 3 days. On day two I came home from work and the slurry was very thick/chunky but a few squirts of water got them going again. Other than that, there was a great slurry happening in there. When I cleaned them out, they are all rough, chipped and scratched. Any idea where I went wrong? I have the beginnings of a great polish otherwise.
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MommaGem
spending too much on rocks
Member since April 2019
Posts: 312
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Post by MommaGem on May 26, 2019 14:17:52 GMT -5
Did you have any cushioner in the mix?
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lancemountain
starting to spend too much on rocks
Member since March 2017
Posts: 214
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Post by lancemountain on May 26, 2019 14:21:15 GMT -5
Did you have any cushioner in the mix? Ceramics- mixed sizes. About the same % as I usually use
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tkvancil
fully equipped rock polisher
Member since September 2011
Posts: 1,546
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Post by tkvancil on May 30, 2019 10:39:10 GMT -5
lancemountain ... I don't think you did anything wrong. Lab has done this to me every time I have tried it. It seems to me the finer the grit the more this happens. My theory is less actual slurry is the culprit. The loose bonds of this particular feldspar probably come into play as well. I think the edges of the layers get beat up and what I would call frosted. The extra thick slurry is also something I have seen before with this rock. It gets uber-sticky if allowed to dry. My last attempt made it to polish before it went bad, looked pretty much as you are showing. It actually looked OK at 24 hours but by the next day ... bam! gone to crap. Shorter pre-polish / polish cycles should help. I will try again some day ( 3 "fails") to date. Maybe a dry polish? Good luck, rock on!
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Post by greig on May 30, 2019 11:00:20 GMT -5
I have tumbled various feldspars, but never labradorite. Reading your description of events, my initial thoughts are as follows: Polish should not directly cause scratches. It will sometimes "bring out" scratches that were not obvious. Yours look like fresh scratches, so probably not the case. Sometimes fresh scratches will happen in polish, if grit or small broken rock from an earlier stage is included by mistake (on a dirty rock or stuck to your barrel). However, I don't think that happened here, because you said the slurry got thick (big hint). It is possible that it got too dry during the run and then the rocks rubbed each other too aggressively (perhaps they were starting to round again rather than polish). The simple answer is to take it back a stage to remove the new scratches and polish again, watching carefully - maybe checking every few hours. For sure, make sure the sound hasn't changed - which would indicate something odd is happening and they are in need of an early rescue. I will monitor this thread to see what experts have to say.
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Post by Garage Rocker on May 30, 2019 13:45:40 GMT -5
Most tumbled Labradorite you see will look similar to this. I tried it in my very first tumble, got similar results, and haven't tried to do it again since then. There is too much nice material out there that will take the tumble well, so I've keep the rest of my Labradorite as rough pieces.
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Post by fernwood on May 30, 2019 13:50:03 GMT -5
Agree. Labro is tough. I babied some, in rotary with about 60% prepolished plastic pellets in 1200 and final polish. They turned out pretty good.
I have much more Labro, but am thinking about not doing final polish and pre-polish in rotary or vibe. Using Dremel for that.
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Post by greig on May 30, 2019 18:24:40 GMT -5
Agree. Labro is tough. I babied some, in rotary with about 60% prepolished plastic pellets in 1200 and final polish. They turned out pretty good. I have much more Labro, but am thinking about not doing final polish and pre-polish in rotary or vibe. Using Dremel for that. What do you think is causing the issue in pre and polish?
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Post by fernwood on May 31, 2019 5:44:15 GMT -5
There are some other rocks that look great until those stages. Those small fractures often do not show up until then. They might have been there from the beginning, but hidden until the surface was smoother.
Hoping someone with more experience than me will offer their thoughts.
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peachfront
fully equipped rock polisher
Stones have begun to speak, because an ear is there to hear them.
Member since August 2010
Posts: 1,745
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Post by peachfront on Jun 8, 2019 10:40:38 GMT -5
Did anyone ever solve this? I had the same issue, one of the reasons I never replaced my Lot-O. I'm actually thinking of selling the rest of my labradorite because I have so much more success with other materials but I'm now all-rotary & I never get much of a polish on the labradorite in the rotary. Even supposedly challenging ones like Neon Apatite did well for me in the rotary. So I've been focusing where it's easy to get a good result... even tho I would love to finish more of my labradorite.
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mooresean68
having dreams about rocks
Member since February 2018
Posts: 52
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Post by mooresean68 on Jun 9, 2019 17:25:49 GMT -5
I've had some lab running for about 4+ months now ( probably over kill I know but hey, set it 'n forget it sometimes ) and these are my similar results. Granted I can't speak to working with a vibratory tumbler but the results seem the same.
Lortone QT66 all the way, no vibratory tumbler. Quantity: About 25 pieces in the 6lb barrel Filler: Aquarium gravel and mixed cylindrical ceramic sizes Images: Results @ 1000 AO and setup for polish.
I decided to try Chrome oxide for what reason, well just because. It's all experimental right now anyway. Probably let the polish run for another 30 days or so, mainly because of how full the barrel is and how many smalls there are; there's quite a lot of work for the polish to get to everything.
Observations: To me it seems to suggest it's all about the rock and the direction of the internal structure, like sanding across the grain of wood.
To Do: After this polish run, my next batch is going to try strictly round ceramics and not the cylindrical type. My thinking is that with the cylindrical shape, the ends which should be somewhat rounded, may hit against a weak spot in the lab causing it to chip similar to a chisel and the weight of material in the barrel is the hammer. I'm hoping that having all round ceramics will prevent that and provide a smoother action within the barrel.
So far: Days
| Grit | Amount TblSpn
| 27 | 70/90 SiC
| 4 | 28 | 70/90 SiC
| 6 | 18 | 120/220 SiC | 6 | 24 | 500 SiC + Borax
| 3 | 31 | 1000 AO + Borax
| 3 | 0
| Chrome Oxide
| 1
| 128
| Total ~4 months
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Images:
Dried after clean out. The top three are pretty fractured but still show tiny to small sections of a good surface, the bottom three are probably the best of the bunch.
Results after 1000 AO: (thought I had the focus dialed in on live view but well that failed)
Water Line
Filler and polish
Topped off and ready to roll
Good luck! I've love to get a solid recipe down for this and will likely be working with it a lot in the coming years. As this is really my first batch of lab I have so much more to learn and experiment with.
Thanks -Sean
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Post by Rockindad on Jun 9, 2019 17:40:03 GMT -5
First thing I think of is to put in some serious time shaping them before they ever hit a tumbler in an effort to minimize the amount of time they are bouncing around in a barrel. If done well 60/90 could be skipped and subsequent grit cycles should be able to be shortened. I just ordered some to punish myself give it a go.
Al
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Post by fernwood on Jun 11, 2019 8:18:48 GMT -5
Great comments. I have a couple more lbs. of Labro and am not giving up. Maybe I will cull the better pieces and do some experimenting with those with no flash. Going to have a barrel open in a week. Tentative plans: Use Dremel to take the edges off. A week in 80 SIC with pea gravel and ceramics. Maybe longer depending. A week in 120/220 SIC with stage specific pea gravel and ceramics. A week in AO 600 with same as above. A week in 1200 AO with stage specific plastic pellets and pea gravel. Since this is the problem stage, will check every couple of days. If I notice cracks, will remove those and replace with more media. 1-2 weeks in either Rapid Polish or AO 12,000 with stage specific pea gravel and plastic pellets. Check every couple of days and cull as needed. A 24-48 hour Borax cleaning between all stages, plus high pressure water wash. Am guessing by the time I am done, there will be 25% Labro and 75% media. Here is some I finished in April. Photo taken before final cleaning. I did not use the Dremel on these prior to tumbling. Total tumble time was 1 month, 3 days.
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MommaGem
spending too much on rocks
Member since April 2019
Posts: 312
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Post by MommaGem on Jun 11, 2019 10:03:40 GMT -5
This morning I just gave a batch of Labradorite a cleaning. I had it in 120/220 for a few weeks with plastic pellets and it's looking really good so far. I use ALOT of plastic pellets (like 50/50), so it takes longer to grind them down, but they look really nice so far. I just moved on to 500 grit this morning. With a fresh batch of plastic pellets, so we'll see how it goes
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peachfront
fully equipped rock polisher
Stones have begun to speak, because an ear is there to hear them.
Member since August 2010
Posts: 1,745
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Post by peachfront on Jun 12, 2019 15:30:30 GMT -5
Please don't forget to come back and update if this works. Otherwise, I might be dumping a lot of labradorite into the garden rocks!
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Post by fernwood on Jun 13, 2019 3:29:23 GMT -5
This morning I just gave a batch of Labradorite a cleaning. I had it in 120/220 for a few weeks with plastic pellets and it's looking really good so far. I use ALOT of plastic pellets (like 50/50), so it takes longer to grind them down, but they look really nice so far. I just moved on to 500 grit this morning. With a fresh batch of plastic pellets, so we'll see how it goes By fresh do you mean unused previously?
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MommaGem
spending too much on rocks
Member since April 2019
Posts: 312
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Post by MommaGem on Jun 13, 2019 8:21:19 GMT -5
This morning I just gave a batch of Labradorite a cleaning. I had it in 120/220 for a few weeks with plastic pellets and it's looking really good so far. I use ALOT of plastic pellets (like 50/50), so it takes longer to grind them down, but they look really nice so far. I just moved on to 500 grit this morning. With a fresh batch of plastic pellets, so we'll see how it goes By fresh do you mean unused previously? Yeah, because I didn't want to transfer the pellets that had been in the 120/220 batch over to the 500 batch. One could also use pellets that had been used in 500 before, just as long as the risk of contamination is gone. (I'm using plastic pellets rather than ceramic media with this batch - just seems gentler on the stones).
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MommaGem
spending too much on rocks
Member since April 2019
Posts: 312
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Post by MommaGem on Jun 22, 2019 15:58:23 GMT -5
My Labradorite just finished the pre-polish with 500 SC and LOTS of plastic pellets - Lookin' good!
Here it is wet...
And here it is getting dry...
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,154
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Post by jamesp on Jul 2, 2019 4:32:42 GMT -5
All felspars are difficult to tumble. They end up having the unsightly surface fractures. Rocks with defined cleavage layers are often tricky to tumble.
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Fossilman
Cave Dweller
Member since January 2009
Posts: 20,666
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Post by Fossilman on Jul 2, 2019 9:26:06 GMT -5
A friend of mine did some, but in a small tumbler 3A Lortone, it came out great... No fractures or breaks..
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