sford13
starting to spend too much on rocks
Member since September 2009
Posts: 119
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Post by sford13 on Mar 17, 2010 13:21:03 GMT -5
Ok I am finding that even though I am still fairly new at this I am starting to notice my flaws more and more. My shine that has been coming out of the polish stage I am pretty happy with. But have two issues that are more common that I would like.
First is what appears to be little fracture lines that end up looking white due to the polish getting in them. My guess is that this might just be due to moving on before their time.
Second one I have noticed is that I seem to have a number that have chips on them. These are not chips out of them. But rather chips that are still attached and rather good. I am starting to look for these better in the earlier rounds as I am not sure which stage they are happening in. I do use plastic pellets in the polish stage.
I have been using a hammer to break down bigger stuff and am wondering if it could be a weak point that slips past so long and appears at the end of the process.
Just wondering if other than watching more closely what I move on, if there is any other ways to help prevent chipped rocks. And once they chip like that would you start them over or just chuck them aside not to mess with them again?
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Thunder69
Cave Dweller
Thunder 2000-2015
Member since January 2009
Posts: 3,105
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Post by Thunder69 on Mar 17, 2010 18:53:07 GMT -5
You are using plastic pellets in your polish stage you might want to use more to cushion the stones and keep them from banging togeather...as for the white residue in your stones ..question is ...Do you burnish? If not do it as soon as you take the stones out of polish so the crack polish dosn't dry in there like cement... If they chip I might send them back down ......John
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revco
starting to spend too much on rocks
Another Victim Of The Rockcycle
Member since February 2010
Posts: 162
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Post by revco on Mar 17, 2010 19:35:04 GMT -5
I, and most people here, will agree with John...using plastic pellets and burnishing in between steps is essential! I use pellets liberally in 500 grit and up, making sure they get all throughout the barrel. These provide two functions - transporting polish and also cushioning the rocks.
Cracking/pits can also be caused by tumbling a much harder material with a softer material. I tumble various rocks together, but I try to make sure they're pretty close hardness wise. Sometimes a rock does have a weakness and the tumbling reveals it later on...just send the offender back to rough or toss it if it's not turning into much.
On the point of cracks from previous steps, I've found it's really important to make sure a rock is absolutely ready to come out of rough. For me, this means the rocks are totally smooth/rounded with no visible pits or major cracks. Some minor hairline fractures are usually fine, but even that can cause problems. Reason being, if any grit from a previous stage gets into the next, it can cause issues for all the rocks in the next step. I inspect all my rocks out of each stage with a magnifying glass because I'll often see a pit that my naked eye couldn't see!
Good luck and I'm sure others will chime in with other details!
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Post by Hard Rock Cafe on Mar 17, 2010 20:57:24 GMT -5
And yes, you may be introducing fractures by breaking your rough with a hammer.
Chuck
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Post by susand24224 on Mar 17, 2010 21:08:02 GMT -5
Hi--I'm happy to chime in with details. I agree with the advice already given, but do things a bit differently, and will approach your questions a bit differently.
Yes, hitting your rocks with a hammer will cause internal fractures, some of which you will not see until after the first one or two tumbling steps. Try it with some translucent rock and you will be able to see what it does. Sometimes you have no choice but to use a hammer alone, but the better method is to use a chisel and hit the chisel. Also try to follow the natural breaking points of the rock. You will still get fractures, but there will be a lot less.
I use ceramic shapes rather than pellets because they are easier for me and serve the same purpose. Your choice, of course. In anything less than a 7 hardness, I add up to 50% to the barrel with the rough at each stage. I also add borax or Ivory Snow if the rocks are brittle (prone to crack). With Mohs 7 if I see surface chips or new fracture points, I add ceramic shapes.
When tumbling different rocks together, remember that hardness is only one factor--brittleness is another. Amethyst and rose quartz are usually Mohs 7, but will get chipped by agates because they are more brittle. This is just one example. The "chips on them" that you describe I often see with brittle rough when I am not careful about separating.
As to whether I would start them over, it depends on the rock. If I absolutely love it, yes I would. The best solution is to grind it off if you have a grinder, or if it is small, you can do it by hand with a "grit paste" on a smooth surface. I think 150fromFundy (did I get that right?) describes this in another post.
Hope this helps!
Susan
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Post by johnjsgems on Mar 17, 2010 23:29:16 GMT -5
Another cause of chipping is underloading drums. This usually happens when the first stage is moved on after loosing volume, and again after second step so by polish drum is not 3/4 full anymore. Rocks fall and chip as the drum rotates.
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sford13
starting to spend too much on rocks
Member since September 2009
Posts: 119
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Post by sford13 on Mar 18, 2010 6:34:11 GMT -5
Well I have four barrels. One dedicated to polish. And usually have two running the course and then use the third for the 120 and pre-polish stages. And I will even use the third for course if need be. So I keep my barrels close to 3/4 full.
I do burnish between all my steps actually. Once a batch is ready to move to the next step it runs in borax for day to clean it up. And I burnish after the polish as well. That one with borax and for a day.
I really think that my problem might be two fold. It might be aggrivated by the hammer busting but is probably the more brittle material being in with the tougher stuff. I have gotten some new rough where I should be able to run a full cycle with the same rock and I am not touching it with the hammer so we will see how that turns out.
Thank you all for your advice and for ideas of where I can improve my process.
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