MommaGem
spending too much on rocks
Member since April 2019
Posts: 312
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Post by MommaGem on Apr 29, 2019 9:42:46 GMT -5
Hello everyone!
I'm beginning again after a very long hiatus from tumbling, so my current batches are just alot of practice and learning.
I'm encountering an issue with chipping during the polish or burnish stage. See the pictures below (this is Carnelian). The actual chips aren't polished at all, so I assume this is happening either late in the polish stage, or during the 24 hour burnish after. I am using well rounded ceramic media during both stages. Do you think I should move to the softer plastic pellets during polish/burnish?
Any recommendations? It's discouraging to get them nice and smooth, and they take a polish really well, only come upon these flaws at the and of the process.
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Post by MsAli on Apr 29, 2019 9:58:15 GMT -5
I switched to plastic pellets and liked the outcome better.
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Post by victor1941 on Apr 29, 2019 10:01:30 GMT -5
Are you using a vibe or rotary? I tumble cabs in a UV-18 vibe and sometimes have a cab break because of internal fractures or just stress during the entire cycle that shows up at the end. The media looks good so I think the top stone shows a non-healed fracture. The second stone also appears fractured. I always run 50/50 media to cab mix and fill the vibe full to cut down on any banging.
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MommaGem
spending too much on rocks
Member since April 2019
Posts: 312
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Post by MommaGem on Apr 29, 2019 10:12:57 GMT -5
Are you using a vibe or rotary? I tumble cabs in a UV-18 vibe and sometimes have a cab break because of internal fractures or just stress during the entire cycle that shows up at the end. The media looks good so I think the top stone shows a non-healed fracture. The second stone also appears fractured. I always run 50/50 media to cab mix and fill the vibe full to cut down on any banging. Thank you! I'm using a Lortone rotary. These stones made it through 6 weeks of tumbling with the various grits and ceramic media, but I had a fair amount chip out at the very end  |
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MommaGem
spending too much on rocks
Member since April 2019
Posts: 312
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Post by MommaGem on Apr 29, 2019 10:13:26 GMT -5
I switched to plastic pellets and liked the outcome better. Thank you! Do you use the plastic pellets through all stages, or just during polish? |
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Post by captbob on Apr 29, 2019 10:34:07 GMT -5
I switch from ceramics to plastic beads from 500 grit on through the polish/burnish.
You're really not removing anything other than the "scratches" left by the previous grit in these end steps, so I think that's a good stage to start babying the stones.
I keep my plastic beads stored in containers marked with which step they were used in.
Don't care to use beads/pellets used in a coarser grit in a finer grit or polish step.
Maybe not be necessary, but I don't take chances that way to avoid cross contamination.
The finer the grit the fuller I have the barrel. You don't want a lot of empty space in fine grit / polish stages. Good luck to ya!
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Post by MsAli on Apr 29, 2019 10:58:30 GMT -5
I switched to plastic pellets and liked the outcome better. Thank you! Do you use the plastic pellets through all stages, or just during polish? If I am running a batch of softer stones I add them after 60/90, if harder stones I add them after the 120/220 stage |
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MommaGem
spending too much on rocks
Member since April 2019
Posts: 312
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Post by MommaGem on Apr 29, 2019 11:33:28 GMT -5
If I am running a batch of softer stones I add them after 60/90, if harder stones I add them after the 120/220 stage Perfect - Thank you! I've placed an order for plastic pellets and will incorporate them into my process  |
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Post by fernwood on Apr 29, 2019 11:56:04 GMT -5
Yes, plastics are much better for later stages. Also, culling anything with fractures. Due to limited vision. I check all rocks under lit magnifier. Cull and safe those that I feel will not be good after final 2 stages.
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harrym
having dreams about rocks
NH - The Granite State
Member since January 2019
Posts: 59 
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Post by harrym on Apr 29, 2019 20:31:35 GMT -5
I use about a 50-50 mix of plastic pellets and tile spacers. Since using both my chipping has reduced quite a bit.
Good Luck!
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kskid
Cave Dweller 
Member since July 2014
Posts: 98
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Post by kskid on Apr 29, 2019 22:54:17 GMT -5
I switch from ceramics to plastic beads from 500 grit on through the polish/burnish. You're really not removing anything other than the "scratches" left by the previous grit in these end steps, so I think that's a good stage to start babying the stones. I keep my plastic beads stored in containers marked with which step they were used in. Don't care to use beads/pellets used in a coarser grit in a finer grit or polish step. Maybe not be necessary, but I don't take chances that way to avoid cross contamination. The finer the grit the fuller I have the barrel. You don't want a lot of empty space in fine grit / polish stages. Good luck to ya! X2, especially the last line. In my experience too much air space is the primary cause of chipping/frosting of rocks. I add pellets when necessary to take up space. The plasticity of the pellets is a coincidental redundancy, IMO. Welcome back to the hobby! |
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,589
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Post by jamesp on Apr 30, 2019 5:53:22 GMT -5
Sounds like too much air space, is your barrel 70/75% filled ? do you hear clattering/banging noises ?
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MommaGem
spending too much on rocks
Member since April 2019
Posts: 312
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Post by MommaGem on Apr 30, 2019 7:33:45 GMT -5
Sounds like too much air space, is your barrel 70/75% filled ? do you hear clattering/banging noises ? It does seem like this is part of the problem. I was keep with the 2/3 full recommendation. There's no clanging noises since I still do use ceramic media, but I do hear movement.
I'll definitely add plastic pellets (50/50) after the 120/220 grit stage, and fill it fuller. I have 4 barrels in 120/220 right now, so this is perfect timing! |
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Fossilman
Cave Dweller
Member since January 2009
Posts: 20,717
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Post by Fossilman on Apr 30, 2019 9:23:23 GMT -5
All my stages I keep the barrel at 3/4 full, even if I have to add filler... It helps out a bunch..
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,589
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Post by jamesp on May 1, 2019 4:22:55 GMT -5
Sounds like too much air space, is your barrel 70/75% filled ? do you hear clattering/banging noises ? It does seem like this is part of the problem. I was keep with the 2/3 full recommendation. There's no clanging noises since I still do use ceramic media, but I do hear movement. I'll definitely add plastic pellets (50/50) after the 120/220 grit stage, and fill it fuller. I have 4 barrels in 120/220 right now, so this is perfect timing! You can always throw a few pieces of delicate broken glass in with your rocks. Check to see if it breaks into smaller pieces. If the glass is breaking you probably don't have your barrel filled enough. Glass cocktail stirring sticks 3 to 4 inches long are good pieces of test glass. |
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Post by greig on May 1, 2019 13:25:33 GMT -5
It does seem like this is part of the problem. I was keep with the 2/3 full recommendation. There's no clanging noises since I still do use ceramic media, but I do hear movement. I'll definitely add plastic pellets (50/50) after the 120/220 grit stage, and fill it fuller. I have 4 barrels in 120/220 right now, so this is perfect timing! You can always throw a few pieces of delicate broken glass in with your rocks. Check to see if it breaks into smaller pieces. If the glass is breaking you probably don't have your barrel filled enough. Glass cocktail stirring sticks 3 to 4 inches long are good pieces of test glass. Really interesting advise. I never would have thought of doing that. I would guess your rocks have to be 6+ Mohs hardness or the glass will scratch. |
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Post by greig on May 1, 2019 13:32:31 GMT -5
With a rotary tumbler, you can usually tell if the rocks are crashing from the sound. Sometimes, the barrel seemed full of rock and media, but after tumbling for a little while, I noticed I needed more media (happens to me when I have larger rocks and did not settle the extra media between them).
Last thought. When I look at the pics of your rocks, I think that I see fractures and not chips. If so, it might be that the fractures were there all along, but became more apparent with polish.
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