crinkle
off to a rocking start
Member since February 2018
Posts: 1
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Post by crinkle on Feb 9, 2018 18:41:12 GMT -5
Hi guys, im a new guy!
I have recently started tumbling and so far results have been... interesting! I really like how when I get my hands on a bag of any given mineral, all the pieces are different and some have other minerals mixed in and each piece is unique. Each time i open up the barrel is a bit like Christmas morning... what will be in store?!
Anyway, I have a 3lb tumbler and the basic set of grits which you can get here in the UK from UKGE. The problem which seems to be ocurring is that the stones really dont seem all that "polished" after the last runs with pumice powder (no plastic pellets). The VERY basic tumbling leaftlet that comes with the tumbler indicates approx 7 days on grit, 7 on medium grit, and then 3-5 on the polishing stage. However, I'm a cynic and cant help thinking all these different minerals will all need slightly different processes to get the best results with them. So I'm wondering, does anyone know of a good book or reference source for the best materials and processes for all the different minerals?
I've done some Amethyst and Tigers Eye so far (separately). When I opened the barrels, all the colours looked lovely, vibrant purples, deep blacks and silvery golden lines shimmering away. But by the time they had dried, the colors were faded and the tigers eye colours had faded to the point they looked like petrified wood. All very smoothed out and nice to touch, but not vivid. I have some Blue Lace Agate and Labradorite lined up, but thought I'd check for some feedback before throwing them, potentially to their ruin!
Cheers in advance!
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Post by aDave on Feb 9, 2018 19:16:22 GMT -5
Congrats and welcome crinkle . Just based on your initial description of your steps, those time periods are too short, IMHO. I know most manuals mention about 7 days for each, but that's just not long enough to get satisfactory results. I'm not saying it can't be done, but with excessive imperfections in your rocks, you increase the likelihood of transferring grit to the next step and contaminating it. That could also be part of your problem. The fact that you see shiny rocks when they're wet, is not uncommon. The water hides the minute scratches from the various stages. If all goes well at the end, a proper polish will leave them looking wet, even when they're dry. Oh yeah, I've never used pumice, so I'm not sure what you are looking to have it do. I don't know of a book off the top of my head...most of my detailed info and learning took place on this forum. There are top notch folks here whose knowledge would probably rival any book you might find. Here's what I would recommend at the most basic level: Tumble rocks that are roughly 6.5 to 7 on the mohs scale of hardness. Even if a vendor doesn't list the hardness for you, Google will usually provide instant results for known rocks. If you are running mixed batches, hardness should be the same, if possible. The harder the rock, the better chance for success at the end. If you tumble a mixed batch where hardness is not similar, the harder rocks will scratch the softer rocks, and a polish won't occur on the soft ones. Agates and Jaspers are usually great for someone just starting out. Very hard, and easy to get decent results. These are tumble times and grits that I would recommend to start out... 1st stage (Coarse grind), 60/90 SiC (Silicone Carbide grit). Run until the rocks are shaped to your liking with most imperfections removed. This might take months to accomplish. Grit change outs every 7 days or so. This stage is typically the most grit intensive in terms of using it up. 2nd stage (Medium grind), 120/220 SiC. Run for 7-10 days. 3rd stage (Fine grind) 500 SiC or AO (Aluminum Oxide). I run this stage for two weeks with no grit change outs. You might want to start with 7 days just to establish a baseline and see what difference changes in this duration might make. 4th stage (Polish) 1:14000 (1 micron) AO. Absolute minimum should be 7-10 days. A couple extra notes: If you are using plastic pellets, there is no need to use them in the 1st stage. Their use might actually inhibit shaping. If you use pellets in subsequent steps, keep those pellets dedicated to that particular stage. Do not move the pellets along with the rocks. Grit may get embedded in them and ruin the results in subsequent steps. I'll let someone else jump in for now. Dave
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Post by Jugglerguy on Feb 10, 2018 11:36:23 GMT -5
I agree with Dave.
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Post by gmitch067 on Feb 10, 2018 12:08:49 GMT -5
When I started the tumbling hobby, I bought the book "Modern Rock Tumbling" by Steve Hart (Published by Little Red Store, ISBN: 978-0-615-19002-0). It was a good read and set me on the right path in an organized manner. More and more my attention was drawn to this RTH Forum to view other member's "recipes" for success. I feel like I am back in college advancing from the beginners 101 series of classes into the Masters classes ... I should be in this series of classes for awhile... FUN!)
Glenn
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Wooferhound
Cave Dweller
Lortone QT66 and 3A
Member since December 2016
Posts: 1,422
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Post by Wooferhound on Feb 10, 2018 12:20:33 GMT -5
I think that pumice would work better as stage 3 prepolish. The stones you have now should only need a proper polishing. Clean the stones by tumbling them in plain water with a small amount of soap Then polish them, hopefully with plastic pellets for cushioning Use a real polish which would be extreamly fine AO Aluminum Oxide or CO Cerium Oxide or Tin Oxide
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