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More On Tumbling

More On Tumbling
By Aislyn Bryan January 15, 2007 8041 Views No comments

We get a lot of questions about tumble polishing jewelry so consider this part 2.

Vibratory versus Rotary

We've added a couple of vibratory tumblers since the tumbling page was written so I can now offer some comparative information. The vibratory definitely works faster. Some people claim the vibratory is more gentle and maybe it is, since everything in it shuffles around on top of the shot rather than rolling in it, but since I've never had anything, even the most delicate wire earrings or stones, damaged in a rotary, I don't know that more gentle is of any actual benefit. The vibratory is quite loud and requires a good deal more shot. Since the shot can cost more than a tumbler, this can be a bad thing. Gary prefers the vibratory tumblers because they hold a lot and they're faster but he's tumbling massive numbers of rings. I still prefer the rotary tumblers for jewelry because I'm never tumbling great quantities at once, I'm never in a huge hurry and it makes a soothing, swishy sound that isn't annoying.

Hardening: Fact or Myth?

Some people say that tumbling doesn't actually harden the metal. I know otherwise because of an experiment we did when we got our first vibratory.

Gary wanted to know how long we should tumble rings in the vibratory in order for them to match the hardness of the rings tumbled in the rotary. He tumbled four batches of 16g/4.5mm rings in increments, increasing by a half hour each time, and put cryptic labels on them so I wouldn't know which was which. I made a bit of chain using our normal rotary tumbled rings in the same size, then I worked with each of the mystery batches of rings to find the one that most closely matched the stiffness of our usual rings. I picked out the match, but I also put the mystery batches in order from the least time tumbled to the greatest, based on how hard the rings were. If the rings weren't hardened by the tumbling, I don't see how it would have been possible to order them as I did. The difference was significant enough that it was quite easy to order them correctly.

Stones and Glass

I still tumble everything I make and I still haven't had any damage... except for one small thing. I tumbled some pink mystic topaz which is actually white topaz with a coating on it that makes it pink. I forgot it was in the tumbler, left it all night, and it was white topaz when I took it out. So again, tumbling anything with a coating is risky business. It could probably tolerate a short tumble but not all night. I recommend test tumbling a single bead when it's important. I wish I'd taken my own advice on that because those earrings were really nice when they were pink. ~wry smile~

If you tumble a dyed stone, it's very likely to lose its dye. The answer to that, of course, is don't use dyed stones. They're going to bleed on your customers' skin anyway so it's better to just avoid them altogether.

Gun Stores

Evidently, vibratory tumblers are used to polish shells for reloading and so are available in gun stores and at a better price. Be aware that weight is an issue with tumblers and stainless steel shot is very heavy. If the tumbler is intended for use with ground walnut shells, rice or some other weightless tumbling media, steel shot is likely to overload the motor's capacity. Also, some of those tumblers are meant for dry media only and can't take the water and soap used with stainless steel shot. So if you shop for a tumbler at a gun store or some other alternative outlet, ask about the weight capacity and ask about using water in it.

Note: The stainless steel shot used for tumbling jewelry is not the same thing as shot used in shotgun shells. Don't buy gun shot for tumbling jewelry.

Yellowed Silver

If you've read our tumble polishing jewelry page, you've seen the bit about the mysterious darkness. Yellowing is the first stage of that darkness, just like it's the first stage of tarnishing. If you get yellow, brown, grey or black on your metal and you've followed the directions for rinsing the tumbler and shot, adding clean water and a lot more Dawn, given it another tumble and it still hasn't gone away, you need to do two things.

First clean your jewelry using the aluminum foil method (below).

Once your jewelry is clean, you have to figure out what contaminated your tumbler. Base metal of any sort is usually the culprit. Some people say that black comes off the inside of the tumbler barrel and gets on the jewelry but I've never known that to be the case and we've done more tumbling than most people will in a lifetime. Of course, we only use Dawn in ours so it's possible that people using some other cleaning compound, perhaps something that damages rubber, would have different experiences. We have worn out tumblers to the point that the metal barrel was peeking through the rubber inside and contaminating the sterling, though, so watch for that if your tumbler barrel is metal and you've used it a lot or the rubber has been damaged in some way.

Tumble scrap sterling to test your tumbler so you don't risk jewelry while you're cleaning it up. If Dawn isn't working to get the black out, put a lot of baking soda in your tumbler with the shot and water and tumble it overnight. Rinse the shot and tumbler really thoroughly because baking soda is slightly abrasive. Then test tumble some scrap sterling with Dawn and water again. I've never seen a case of an undamaged barrel that wasn't cleaned by this method.

Aluminum Foil Method

Line the bottom of a glass pan with aluminum foil, shiny side up. Boil water. Lay the jewelry on the foil (it must be touching aluminum) and sprinkle it with a generous amount of washing soda*. Let the boiling water cool a bit and pour it in the pan to cover the jewelry. Bear in mind that some stones are sensitive to heat. I cracked some fluorite doing this but that's been my only casualty. You'll see bubbles forming. Very quickly, the tarnish will jump off the jewelry and get on the aluminum. It just takes a minute, then you can remove and rinse the jewelry and it'll look nice again.

* Washing soda is an old fashioned laundry additive that might be difficult to find locally. Fortunately, you can easily make washing soda out of baking soda. Baking soda will work in this process but it doesn't work as well as washing soda.

Where to Buy Stainless Steel Shot

There are many places to get it but it's hard to buy something you've never seen before, so here's a link:

Stainless Steel Shot

I would recommend two of those with a 3lb. Lortone tumbler but 1 pound will work, it just takes longer.

If you have tumbler questions, please feel free to post them in the comments and I'll do my best to answer.

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