stoneblue
starting to shine!
Rockin' & Rollin' Across America
Member since September 2007
Posts: 43
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Post by stoneblue on Feb 16, 2008 15:55:56 GMT -5
OK, I've been tumbling a few batches of rocks now & one thing I've been noticing is no matter how full the barrel of rock, or how much filler, or how full of water or ratio of the stone size, I always have some that crack. It may only be a hairline crack, but nonetheless it's there. It occurs whether it's an all agate or all quartz batch. Usually there is about 10% to 15% with some sort of flaw. I'm curious if anyone else has this problem and if so, how do you deal with it. Also I've seen some finished stones pix on the board with slight cracks. I'm wondering how tolerant of cracks people are in their finished product.
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Post by deb193redux on Feb 16, 2008 17:13:02 GMT -5
Tolorance varies. Some cracks are in the rock before we start. Maybe many. Rocks are hard and I don't think tumbling really cracks that many. Chip maybe, not crack.
Of course some cracks get highlighted when grit or polish gets in them. Just try to burnish/wash carefully.
If you are really obsessive, when you see a crack, you can break the rock and move it back to the rough grind.
Getting higher quality fracture free rough to start is very helpful. Some types fracture less. For example you will almost never find any AZ Pet Wood that tumbles up w/o fractures. Other types like Dalmation Jasper shape up well and seldom have fractures.
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Post by johnjsgems on Feb 16, 2008 23:38:25 GMT -5
Tumbling cracked rocks gives you shiney cracked rocks. Better to cull the cracked, not so good ones and proceed with the better ones. It may mean doing several (or many) 1st step grinds to get enough good step 2 rocks. You will have better finished rocks that way.
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stoneblue
starting to shine!
Rockin' & Rollin' Across America
Member since September 2007
Posts: 43
|
Post by stoneblue on Feb 17, 2008 0:15:53 GMT -5
John, That's what I've been doing (removing the cracked ones) and then either regrinding or recutting them, or if they are too bad, they become driveway filler.
Deb, I hunt and slab all my own rocks. I inspect them after they are slabbed so I can put a pattern I intend to cut / grind on them in a nonfractured area, if they have cracks at all. Much of the stuff I slab appears to have no cracks when I cut the preform out, even after it's ground. It's just after the tumble that it comes out. And sometimes it doesn't show after the rough tumble, only after I get them out of the polish. Who knows?
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Post by deb193redux on Feb 17, 2008 4:05:22 GMT -5
Well, then if someone else can polish some of you rock w/o cracks, or if you can polish something like Fancy Jasper or Bloodstone - then its one step closer to solving the problem.
Good luck.
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Post by Cher on Feb 17, 2008 8:59:27 GMT -5
I'm wondering how tolerant of cracks people are in their finished product. Cracks I don't tolerate. If they are special stones they go back into the redo box (touch up by dremel if needed), if they aren't they become filler for other loads. Most of the time "cracks" will collect polish which really makes them look bad. On the other hand if it's a fracture that's smooth, it will find a place in a jar or bowl. |
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