newpolisher
off to a rocking start
Member since December 2017
Posts: 1
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Post by newpolisher on Dec 17, 2017 18:21:25 GMT -5
Hello, I have a few questions regarding rock tumbling: I know that various stones have different hardness and should be tumbled separately......but does this go for the polishing stage as well or is it possible to polish various hardness of stones in the final stage? Also...with regards to using filler to stop stones from getting chipped etc, are plastic beads in the photo good to use? I was told by someone in a hobby store that these could be used and as my daughter has some, thought I would give them a shot. Thanks in advance. Attachments:
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Post by rmf on Dec 17, 2017 19:46:40 GMT -5
Do you know Mohs's scale of hardness?
Agates, Jaspers and Quartz are all hardness of 7 so they can be tumbled together in smal tumbler barrels. However in a 12lb tumbler barrel the which has a bigger diameter the quartz can chip because it is a large single crystal and the agates are like 3-D bed sheets with the microscopic quartz crystal woven and twisted together. this means agates and jaspers are tuffer even though they are the same hardness. This is only important for you if you have a barrel > than 4" .
If you have an Agate you can use it to test other rocks and seperate the stones by hardness.
Can you tumble them together? Yes but there are consequences. softer stones grind away faster than harder stones. The more the stones grind away the more material you need to add to get a good polish. Recommendation is to tumble by hardness groups (as in hardness of 7 quartz family, hardness of 6 glass and obsidian, sodalite etc)
To avoid using fillers. start with coarse grit tumble them until they are as rounded as you like but for at least a week. (so tumble from 1 to 3 weeks) If you are a newbie just tumble in coarse for a week and learn the process then tweek from there. Do two batches in coarse first. the when you go to the medium/220 grit put the stones together to maintain a 80 to 90% filling on the Drum. Tumble in medium for a week. Then go to fine tumble 1 week. add a couple of drops of soap (assumes liquid or a pinch of powder) to the fine grit to reduce surface tension. Adding soap also helps remove the grit when you wash them off later.
Now run in polish, your drum should be about the right % full since most of the rock lost in tumbling is lost during coarse grinding. also add a couple of drops of saop to the polish as well. If you tumble all the rocks (hard and soft) together you must seperate them out for polishing if you want a good polish. Or do them all together and the ones that do not polish well will be the softer stones.
The plastic beads used will probably work they are used for cushioning. You should only need extera cushioning for soft stones and only in the polish. be sure to use small stones 1/4" x 1/2" for cushioning they should be 20 - 25% of your tumbler load. they can be screened out and reused for other batches if needed.
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Post by youp50 on Dec 17, 2017 21:40:58 GMT -5
Plastic beads in a rotary tumbler. They are always used for the same grit is. Some for 220 and others for 600 grit. Those beads you have are hollow. They will likely carry grit. You would not be happy with beads carrying 220 grit into a 600 grit step. They would never get a shine on.
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Post by spiceman on Dec 17, 2017 22:02:26 GMT -5
If you use seperate barrels for the different grit sizes just do the same thing with the beads. You will know if it works. But also.... Is it a big enough cost savings from using ceramics. You already know they work. It's a lot of hassel for saving pennies. First, get all the steps for the tumble working very well. Then try different things, if you want.
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