Post by alistair on Jan 5, 2021 10:17:41 GMT -5
I have just completed my first ever rock tumble, using a National Geographic rotary rock tumbler. I did not use their grits though, i used grits bought from Manchester Minerals. I recorded the tumble progress on another thread titled "how to get those rocks to shine".
Here are the steps of the tumble:
80 grit = 3 weeks
220 grit = 1 week
400 grit = 1 week
- borax run to clean rocks = 8 hours
Cerium oxide polish = 1 week
Ivory Soap to burnish = 12 hours
Most of the rocks completed the tumble nice and smooth and well polished. The aim of this thread is to understand what went wrong with the labrodorite and indigo gabro. Both of these rocks types were doing very well through all stages, 80 grit, 220 grit, 400 grit, borax. They looked amazing throughout, glimmering from inside just like opal. We were most excited by these two rock types. I had no idea what was about to happen. After the polish stage, they were battered, bruised, scarred looking, and all of their glimmer was gone. The labrodorite has a terrible frosty appearance. The indigo gabro looks terrible. All other rocks came out fine, such as red jasper, yellow jasper, polychrome jasper, aventurine, rose quartz etc.
What i can say is the tumbler was 3/4 filled for each stage, i used plastic pellets at every stage, increasing the volume of pellets in the tumbler at each new stage as the rocks themselves were getting smaller. I used brand new pellets at every stage, never using the same pellets twice. After all initial stages the labrodorite and indigo gabro looked fine, so i dont think the pellets themselves are the issue. Though i will say the volume of pellets used in Polish stage were considerably more than in prior stages, maybe twice more. After the borax stage cleaning stage they were still fine and on track to be the best looking rocks of the batch. After the polish stage, they came out looking battered, bruised, and the labrodorite frosty. I cannot understand why, the only difference here was the polish medium, all other steps taken were the same as previous rounds.
Could it really be the increase in pellets? I think not as pellets were used in all previous stages.
Does anyone have any suggestions what might have gone wrong here with these two rock types?
Here are the steps of the tumble:
80 grit = 3 weeks
220 grit = 1 week
400 grit = 1 week
- borax run to clean rocks = 8 hours
Cerium oxide polish = 1 week
Ivory Soap to burnish = 12 hours
Most of the rocks completed the tumble nice and smooth and well polished. The aim of this thread is to understand what went wrong with the labrodorite and indigo gabro. Both of these rocks types were doing very well through all stages, 80 grit, 220 grit, 400 grit, borax. They looked amazing throughout, glimmering from inside just like opal. We were most excited by these two rock types. I had no idea what was about to happen. After the polish stage, they were battered, bruised, scarred looking, and all of their glimmer was gone. The labrodorite has a terrible frosty appearance. The indigo gabro looks terrible. All other rocks came out fine, such as red jasper, yellow jasper, polychrome jasper, aventurine, rose quartz etc.
What i can say is the tumbler was 3/4 filled for each stage, i used plastic pellets at every stage, increasing the volume of pellets in the tumbler at each new stage as the rocks themselves were getting smaller. I used brand new pellets at every stage, never using the same pellets twice. After all initial stages the labrodorite and indigo gabro looked fine, so i dont think the pellets themselves are the issue. Though i will say the volume of pellets used in Polish stage were considerably more than in prior stages, maybe twice more. After the borax stage cleaning stage they were still fine and on track to be the best looking rocks of the batch. After the polish stage, they came out looking battered, bruised, and the labrodorite frosty. I cannot understand why, the only difference here was the polish medium, all other steps taken were the same as previous rounds.
Could it really be the increase in pellets? I think not as pellets were used in all previous stages.
Does anyone have any suggestions what might have gone wrong here with these two rock types?