How to polish a single rock?

November 28, 2005 11:33 AM

I think I have a great idea for a Christmas gift, but I'm not sure I understand rock polishing...

I have a rock that I would very much like to make into a pendant for my SO. I'm flexible on how to "dangle" the pendant, via leather strap or some sort of chain-attachment. The crucial step here is the polishing, which I'm not sure I understand how to do.

I have googled it, and based on both time constraints and my desire to keep the rock in basically the same shape it is now, I think I should get a vibrating rock polisher, like this one. I've read a basic introduction to rock tumbling, but I can't seem to figure out if it's going to work to polish a single, meaningful rock. Should I load up the drum with the one rock I want, and lots of others that I don't care about (and that are distinguishable)? Or is there a pellet system I can insert? More importantly, is this process going to give the results I want, or is it just going to trash the rock?

posted by headlessagnew to sports, hobbies, & recreation (2 comments total)

Will your rock scratch glass? if so, use tempered glass bits as your polish medium add tin oxide or chrome oxide and a bit of water and let it rip, it usually takes about five days to polish, the glass will wear down faster than your stone. If glass scratches your stone, then use plastic pellets, plus your polish.
patience is key, I made a small polisher out of a wand type vibrater,with a plastic tupperware screwed to the head
it worked ok for the small jade piece I found on the beach.
posted by hortense at 12:06 PM on November 28, 2005

My experience is with tumblers, not vibrators, so take this with a grain of...uhh...grit.

In tumblers, one rock alone in grit isn't going to do a whole lot. The action of polishing and rounding happens because of the rocks bashing into each other thousands of times, with grit between them to soften the blow and grind away at the material.

If you're going to tumble, you're going to need all the various stages of grit and an appropriate number of similar rocks (in size and material). Some materials don't work well, so bring your rock to a rock shop to get their opinion. It may be too soft and will disappear into the grit, or too hard and won't polish the way you want. Rule of thumb is that anything with clearly deliniated striations may come apart, or may end up with one stripe ground down much further than the other.

Another possibility would be to have the rock 'shaped' rather than polished. The shaping (grinding, polishing on a water wheel, etc.) is a much quicker process and may end up with a nicer final product. You'll need to pay for this service, of course.

Anyway, good luck with this...you're starting at the right time for Christmas. This can take a while.
posted by Kickstart70 at 12:12 PM on November 28, 2005