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Post by Susan on Jul 17, 2004 9:52:36 GMT -5
I was wondering what is the hardness (on Moh's scale) of tumbling grit. I don't know if there are different compositions of grit, but mine is black and may be cer???-oxide. Also, what chemical name am I looking for? I can only remember part of it. Thanks! I used my member name, but it said I shouldn't so I'll use Susan instead of georocks. I'm a newbie
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Post by sandsman1 on Jul 17, 2004 10:39:08 GMT -5
HI AND WELCOME GEOROCKS take alook at this link and brouse around it answers alotta questions if ya dont find what your looking for come on back and ask i realy dont know the hardness of grit but this link will give you an idea where to start and with what --seeya---john www.jaderockshop.com/tumbling_instructions.htm
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Mazanec
spending too much on rocks
Member since March 2004
Posts: 355
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Post by Mazanec on Jul 17, 2004 14:34:34 GMT -5
Black SiC is a man made mineral with a high thermal conductivity rating of 100 W/m-K. It is extremely hard, around a Mohs 9.1 or 2550 Knoop. It has high strength at elevated temperatures. For example, at 1000oC, SiC is 7.5 times stronger than Al203 (aluminum oxide). Black SiC will contain some free silicon and carbon and thus is not as pure as green SiC. Black will range in purity from 97-99% pure, depending on grit size.
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Post by connrock on Jul 17, 2004 14:52:12 GMT -5
Hi Susan and welcome!!! The grit you're looking for is called silicone carbide and it has a hardness of about an 8 on the Moh's scale. If you try to tumble anything harder then a 7-8 you'll have to use diamond powder and that's a "tad" expensive!!! Some people think that the more corse the grit the harder it is but it's all the same hardness. The "norm" for tumbling is to start out with 60/90 which is an ungraded grit.It is made up of grit starting at 60 and has other sizes up to 90 all mixed togeather. You can buy graded grit but for the most part,especially for someone just starting out,you'll just be wasting your money. I said the "norm" is to start out with 60/90 grit but I'm not normal,,,,,,,,,at least my wife says so,,,, and start out using a graded #30 grit. I talked to a lot of people who have tried this method and they ALL told me to forget it because after a week in the tumbler all you'll have is dirty water and the same grit you started out with.Well,,,,,,, I'm quite stuborn and VERY thick headed so I bought 5 lbs and off I went. I was upset when I found that the "pro's" were right!!!!Well as I said I'm a "tad" thick so I kept experimenting with it and finally found the right "recipe"!!!! What I'm trying to say is that by all means start out by using the traditional methods until you get your rocks to shine like you want them,,,but,,,,,,,after you "think" you've got it down pat DO NOT be afraid to do a little experimenting on your own!!! Good luck and let us know how you're doing. Tom
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