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SS Shot Tumble Polishing Problem

I have recently had a problem with small pieces of sterling silver coming out of my stainless steel tumbler with small dark specks on them. They don’t wash off, but, with some effort, I can pick them off with a finger nail. My fear is that it is rubber from the tumbler barrel. The most recent occurrence was on a couple dozen french ear wires that I had made from 20 gauge wire. I did not polish them with any type of compound before tumbling. The time before I had polished what I was tumbling on a wheel first and assumed that it was polish residue. Before I talk to the people who made the barrel, does anyone reading this post have any ideas? I have cleaned the barrel and shot and will try again just to see if recurs. Thanks…Rob

Rob - the black dots can indeed be from your rubber barrel. If you use proscribed chemistry like Rio’s sunsheen burnishing compound, you will delay or avert this. If it is still happening, you can clean your barrel and the shot and jewelry with a can of regular coke that has no remaining bubbles. Run the mess as if you were tumbling for about 45 minutes, then rinse thoroughly with water and dry it all. Inspect the inside of your barrel for soft spots or uneven surfaces. These indicate that the barrel is done. Replace it or better purchase one of the plastic barrels that would run on your machine.
Another possibility would be residual dirt on the silver or shot or barrel. That can be corrected as described above.
Running too long can cause breakdown of the silver or barrel, maximum time is under one hour for all burnishing.j

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It could be polish residue contamination, especially if you reused the water from that contaminated run.

Black tumbling deposits have been discussed here many times over the years. Some of the suggestions include:

Cleaning the barrel and shot with ammonia or coke, including removing residue and running the tumber with the cleaning solution.

Determine if the rubber barrel is disintegrating on the inside and needs replacement.

On a regular basis, neutralize your pickled pieces in a baking soda solution and rinse before tumbling, and use distilled water and a neutral PH tumbling solution instead of tap water and/or soaps.

Thanks for getting back to me. I do run the same burnishing compound mix from one run to the next because my runs are very small. I also will sometimes do a Tripoli step before before tumbling and I may not have clean all the residue off. I have cleaned the barrel with flat coke in the past. Actually, one time it was still a little lively and nearly blew the top off the barrel. I will keep working at it. I would doubt that the barrel is the problem as it is only a couple years old and very rarely used. Thanks again…Rob

Judy…Thanks for getting back to me. I do run the Rio burnishing compound mix, but use the same load from one run to the next because my runs are very small. I also will sometimes do a Tripoli step before before tumbling and I may not have clean all the residue off. I have cleaned the barrel with flat coke in the past. Actually, one time it was still a little lively and nearly blew the top off the barrel.

I have a double tumbler cart with 2 TV10s, one with ceramic cones and the other with resin cones and a close flow through system. I also have an AV 25. I just haven’t gotten in the habit of using them because I work one piece at a time and it is just easier to polish on the wheel after an abrasive wheel cut down. Years ago I had big runs when I was doing shows and this level of work justified using the tumblers. Using SS shot in my little 6 quart tumbler seems to work well for small pieces like earring wires. I would doubt that the barrel is the problem as it is only a couple years old and very rarely used.

I will figure it out, I was just looking for ideas. Thanks for taking the time to offer them…Rob

Thanks again…Rob

I have heard a suggestion to put a glass container into the rubber barrel, something like a pickle jar or any other glass jar that will fit, and put the shot and your item being tumbled into the glass container. I have not done this myself as I don’t have a problem (yet) but sounds reasonable.

Thanks, you would be taking away contact with the rubber, but you would also be missing the flat sides cast into the rubber barrel that make the shot tumble correctly…Rob

After giving the barrel and shot a good soak and tumble in flat coke and then rinsing it all well, I ran another couple dozen ear wires. Everything came out clean. I think that the lesson is to clean the shot and barrel more often and do a better job cleaning what I am tumbling if it has been polished on a wheel. Thanks to all for the help…Rob