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How to turn a rock into a real gem.

, 03·23·10

Hobbyist or geologist, getting your hands on a great specimen is a thrill. But if you want to bring out the real beauty of that stone, you're in for quite a chore. There's shaping, scratch removal and polishing to be done. And when you're dealing with a decent quantity of rock at one time, you've got a pile of work ahead of you, unless you automate. That's where our industrial grade MT Series Barrel Tumblers come in.

We're getting an increasing number of calls from the rock tumbling community, all asking what type of tumbler we recommend to automate the rock polishing process. Every time we recommend a tumbler from our MT Series, the positive feedback is rock solid.

Of course we provide a good bit of guidance when it comes to what media to use as well, recommending the use of silicon carbide followed by aluminum oxide.

For those of you who are interested in polishing up nature's geological treasure chest, here's the step-by-step process.

The first tumble is to shape raw rock, and being much harder than rock, coarse 80 mesh silicon carbide grit is well-suited for the job. When these large particles of silicon carbide are caught between tumbling rocks, they create tiny scratches. This steady grinding wears down the rocks resulting in smaller, rounded specimens.

On the second tumble, medium grit 150 mesh silicon carbide grit is recommended to remove any scratches in the rocks left by the 80 mesh. (Remember, the smaller the number, the larger the abrasive particles, just like sandpaper.)

The third step is often done with 500 mesh silicon carbide or 500 mesh aluminum oxide polishing powder. This step removes scratches left by the 150 mesh, smoothes the surface of the rocks and prepares them for polishing.

To polish, use very fine aluminum oxide polishing powder in a final tumbling step, which buffs the surface of the rocks to a bright luster.

One more essential to rock polishing doesn't have to come from us at all. It's a pair of safety glasses, which are a must in any process involving grit and barrel tumbling.

So good luck with your geological endeavors, be they for pleasure or for profit. And if you're already successfully using the equipment and supplies described above, tell us what you've learned, and with your permission, we'll share what you've learned with the rest of our readers.

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