aimeesrockworks
spending too much on rocks
I really do look like my avatar... it kinda freaks me out.
Member since December 2010
Posts: 458
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Post by aimeesrockworks on Mar 18, 2011 11:54:32 GMT -5
Well, I've done this twice so it's about time I asked for help... I bought a tumbling mix from The Rock Shed to practice with so I wouldn't harm rocks I loved. Now after two mixed batches I've had lovely results with the orange/brown agates and anything dark in color. But all of my translucent quartz (clear, blue, rose, amethyst, citrine, etc) comes out of the polish looking like it just came out of the 120 grit. /insert sigh Now my geology background has me thinking that these 'pure' quartzes should be the hardest of the batch... but perhaps I've been steered wrong. I used ceramic in both batches to make up for the lost volume. Does clear quartz hate ceramic? Does it not do well with burnishing? Or have I stumbled across a slight variation in hardness that has taught me the lesson of tumbling clear stuff by itself? Maybe I'll just have to buy more to test it out!!
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blr2449
has rocks in the head
Can I retire now?
Member since January 2011
Posts: 554
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Post by blr2449 on Mar 18, 2011 13:45:22 GMT -5
My first batch ever, Rock Shed mix, just went into the burnish stage today for about 4-5 days. When they come out I'll check and let you know how the quartz came out.
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Post by Toad on Mar 18, 2011 13:52:30 GMT -5
The quartz tends to fracture/chip more easily than agate which whould give a more frosted appearance if it wasn't ground enough in the first stage or it can just fracture more easily as it goes down the successive steps. A lot of care needs to be taken with the quartz
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Post by susand24224 on Mar 18, 2011 14:18:14 GMT -5
What toad told you is correct--and I will add a bit to it. Although the quartz is hard (as in your geology background) it is also brittle, i.e., it fractures easily. It has also, in my experience, often taken longer to polish than the "ordinary" Mohs 7 rocks. An experiment you can try is to put some polish on a soft piece of leather and vigorously rub your nonpolishers across it. If the spot where you are rubbing becomes shiny, then they probably just need more time in polish. With some rocks, two or even three weeks in polish is required. If you get the shiny spot, just put your nonpolishers back into polish with some extra ceramics to take up the extra space and let it go a few more weeks.
If your spot doesn't become shiny, then your problem could be "contamination." This means that some of the earlier grit remained in the barrel messing up a delicate polishing procedure. Although in theory contamination should affect ALL rocks in the barrel, in my experience it does not. Rather, it affects those more sensitive rocks the most.
Then there's the burnishing step. Some rocks seem to develop a film that is helped tremendously by throwing them back in the barrel, with water almost to the top, and borax, Ivory Snow, or shavings from a soap bar added.
Hope one of the above fixes the problem for you!
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aimeesrockworks
spending too much on rocks
I really do look like my avatar... it kinda freaks me out.
Member since December 2010
Posts: 458
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Post by aimeesrockworks on Mar 18, 2011 16:07:40 GMT -5
Thanks for the advice! It hadn't dawned on me the pure quartz might be more prone to crankiness. I'll give 'em another go in the polish and see if that 'saves' them.
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stefan
Cave Dweller
Member since January 2005
Posts: 14,095
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Post by stefan on Mar 18, 2011 20:21:25 GMT -5
Polish type can have a negative effect also. Aluminum oxide polish seems to be "harder" than most polishes. It often takes some time to "break-in". I always save my used polish and add it back in on the next stage (oddly enough I start with about 2 tablespoons of polish and end up with one). If I ever have to start with all new alum oxide I run it an extra week
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rollingstone
starting to spend too much on rocks
Member since July 2009
Posts: 236
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Post by rollingstone on Mar 18, 2011 23:31:39 GMT -5
How long did you leave it in polish? I find the polish stage takes anywhere from 9 to 21 days with aluminum oxide, and since quartz is one of the harder rocks (as you note), it makes sense that it would be near the longer end of that range. -Don
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