electrocutus
spending too much on rocks
Member since October 2020
Posts: 333
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Post by electrocutus on Jan 25, 2022 14:44:05 GMT -5
I experimented a bit with using plastic pellets in my rotary tumbler for the polishing stage, and I have been wondering if they absorb some of the polish, requiring me to use more polish than I would normally use.
I think I'll stop using them anyway in favour of ceramic media, but since I still have some of it, I don't want it to go to waste.
I find that even if I use the plastic pellets only in the polish stage, the pellets come out grey. That's to be expected since the slurry is grey, but does that mean that a portion of the polish (AO) also gets in the pellets and there is less available to do the actual polishing? The last barrel I polished didn't come out as well as I expected, so I was wondering if it could be because of the pellets.
Thanks.
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Post by tims on Jan 25, 2022 17:11:31 GMT -5
If your ceramic hasn't been all the way through polish it's going to be a bit coarse for polish stage and may give you more headaches than the plastics. I assume the plastics do hold a bit of your polish and mud (hence the color) but if they're only used for polish stage don't know how that would hurt anything, other than the plastic not giving a hard surface to grind against. The plastic should only hold stuff on imperfections on its surface, it won't absorb anything unless you're using foam or something porous.
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Post by Bob on Feb 3, 2022 11:11:31 GMT -5
I've been using 3/8" ceramics for some years, though not in polish on purpose. The interior of them sometimes has internal cracks, which are hard to see. I guess it's quality control or difficulty in the making, not sure. But it has scared me away from trying them in polish. I've also tried 1-2mm spherical ceramics in polish and it was a big mess and also ruined the polish batch.
I use plastic beads available from Kingsley North. They are black and float. Most of them have been used in polish over and over for 5 years or so now and work great. Beads from other suppliers have not done well for me and some have driven me crazy they are so hard to deal with. I used to keep the beads for different polishes (alum ox, tin ox, cer ox, chrome ox) separate just in case, but I no longer do that and have noticed no bad effects as long as I rinse them well.
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Post by perkins17 on Feb 3, 2022 11:41:09 GMT -5
I am in favor of ceramic media, not plastic. I found plastic to be hard to work with and believe it impedes grinding action. Ceramics can be used all the way through, like rocks. Hope that helps!
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Post by greig on Feb 3, 2022 12:02:37 GMT -5
For sure the coarse grits penetrate some of the plastic beads. I don't think the polish penetrates. However, it might coat the beads in polish, just like it coats the rocks a little bit. I don't see that as an issue and wouldn't add more polish because of it. I have noticed that there is less coating of polish on beads and stones if I have too much water, but that makes the polish less effective. Still, I while like ceramic media better, both work.
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Post by Bob on Feb 3, 2022 12:12:41 GMT -5
I am in favor of ceramic media, not plastic. I found plastic to be hard to work with and believe it impedes grinding action. Ceramics can be used all the way through, like rocks. Hope that helps! I found plastic beads inhibit grinding also on grits larger than 220.
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hypodactylus
spending too much on rocks
Member since July 2021
Posts: 467
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Post by hypodactylus on Feb 3, 2022 15:48:22 GMT -5
It is my understanding that grit (including polish) can become embedded in plastic media. I believe this is why people may recommend not mixing plastic media used in different stages. As for 'absorbing' enough to make any difference in how much polish you use; I don't honestly think it will make a big difference.
I personally despise using floating plastic pellets; they are a pain during cleanout stages and I don't like to keep that many separate stashes of media. I use the same ceramic media from stage 2 through polish. Occasionally I will use it in stage 1, but not usually. I keep a separate stash of ceramic media that has been through the polish stage, in case I need to add more to later stages.
I have used rubber tile spacers (they sink) on more sensitive rocks (in addition to ceramic media), but I still haven't determined whether or not that is any better than just using ceramic media. It worked well with obsidian though.
By the way, I only use rotary tumblers (I don't have a vibrating tumbler).
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terryjh
starting to shine!
Member since July 2021
Posts: 46
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Post by terryjh on Feb 4, 2022 12:26:44 GMT -5
I too gave up on plastic pellets. Grit get embedded in them. I also felt that the polishing energy/pressure, and the intended abrasion, gets absorbed by the plastic and not transferred to the rocks. I use all ceramic now.
Terry
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