Tumbling media depositing weird colors

Hi all,

I just took a batch of jewelry out of my small rotary tumbler, and sterling
silver pieces have orange rust-looking spots on them, cast brass pieces
looking like they have bad fake tans, but the pre-fab brass wire looks

I’m wondering if I tainted the media, and that because I run long tumbling
cycles (usually 2-6 hours at a time) it’s burnished on the media and I need
to totally replace it?

Here are some more details:

  • My last tumbler started darkening pieces after a year of use; I
    figured it was that the rubber gasket starting to break down, the media got
    stained from it, and the stained media deposited black on my pieces
  • I bought a new barrel and ran it with water/white vinegar then
    water/baking soda cycles but things started looking vaguely dark more
    quickly than last time; After cleaning just the barrel and gasket this way
    I added the tumbling media and repeated the cleaning cycles
  • Last time I cleaned my tumbler and media I did water/vinegar cycles
    but forgot the water/baking soda cycle and wonder if this is the culprit?
  • I use mostly blue pyramids and some steel shot
  • I use Dawn soap
  • I tend to tumble for 4-6 hours at a time

Any thoughts would be greatly appreciated, thanks in advance!


G’day Sarah,

I must ask you, are you using cold water in your barrel?
I had this similar issue. I did everything I could think of …for me it was simple.

Don’t use chemicals. Simple just wash with soap and water.
Pickle your item wash off your item after you pickle it. Soap and water is fine, next fill barrel with cool water and your soap.

I always dry my steel shot if I’m not using the machine again for a little while. I use a strainer to tip my shot into then tip the shot onto a old tee towel to dry, I also air out my container till it’s dry, then pour my shot back into the barrel.

I do hope this works for you, the rubber melts with vinegar, and hot water. It degrades.

Best of luck

I use baking soda to clean my stainless steel shot. I put a tablespoon of baking soda in with the shot, add water until the shot is just covered and tumble for 20 minutes or so. Always worked for me.

It’s possible I’ve been using lukewarm water, but never hot to do my
cleaning or tumbling. I do exactly what you both have mentioned re: no
chemicals, strain the shot and dry it, let the barrel air dry, wash media
with baking soda.

I guess specifically my question is, is it possible that I’ve somehow
burnished some kind of contamination into my stainless steel shot and blue
pyramids and that I should replace them to start fresh?


First clean your shot and barrel with a can of regular coke - let the coke sit to have no carbonation first. Run for 45 minutes with all your jewelry. Empty barrel, rinse.
Using a compound intended for barrel finishing, NOT dawn, run your metals separate - at least separate the brass from the sterling. Run for 45 minutes, max. the separately run the brass pieces. Again for 45 minutes, max.
for the future, get a clear or translucent plastic barrel, use a purpose made compound for barrel finishing - burnishing is different from abrasive (your green triangles). Use a jewelry supplier for these - there are many that work, but buying a barrel that might be used for rock tumbling means that you don’t know what you are dealing with. The black rubber ones break down. In my shop I use compounds from Rio Grande - burnishing liquid and deburring compound. Both are supplied in concentrate form and for convenience, I mix them each in a gallon bottle and then just use the necessary amount for a run.
Because you are running long cycles, it is certainly possible that the brass transferred to the silver. It is far more likely that the combination created some kind of battery or plating process.
I wrote a book on the subject - it might be useful to you in the future - “Tumble Finishing For Handmade Jewelry” the jewelry supply houses carry it, not Amazon.

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Hello Sarah. my experience: lots of tarnishing in tumbler ( black barrel). Tried many products, including rio grande fancy and expensive products. nothing worked permanently. one day I decided to try just plain white vinegar instead of water. guess what? It worked! I only use white vinegar instead of water. no dawn soap. or any soap, a waste of time. believe me it sounds scary but try it. i dont know the chemistry involved, I am just a housewife who does silversmithing, everything I have learned about polishing and putting shine in silver pieces I learned the hard way. thats my two cents… hope you try it. and yes my black rubber barrel looks like xxxx but the pieces come out spectacular!! I started using vinegar last year, i still use same barrel , it is ugly and used up but it gets the job done better than with anything else i have tried from Rio. :). by the way, i leave my pieces in tumbler with vinegar all night, at least 4 hours and they come out like i said spectacular.

Hi Sara,
I am just going to add that I have tumbled in the same black rubber barrel since 2007. The first few times my silver turned black and I used flat coke to clean the residue. Then it has never happened again. I use cold water with some Ivory soap shavings added. Not detergent which I feel wants to eat the rubber. I also agree that tumbling brass and silver together will cause the problems mentioned. I would separate metals and rinse the media between tumblings. I never let my solution sit in the barrel for days on end, but rinse and dry at the end of the day. So far so good for me anyway.

Thanks for all the input! I’m currently letting my Coke go flat so I can
get cleaning. Going forward I’ll be tumbling my brass and silver
separately, using cold water, and purchasing de-burring compounds
specifically for brass and silver.

And I have your book, Judy, and love it! I bought and read it before I
started tumbling (so the information hadn’t stuck through practical
application), I moved and misplaced it, but just just dug it out and
re-read it. A question for you re: tumbling pieces with set stones: My
preferred finish is the allover satin-y look that I get by stopping after
the pre-finishing stage, but some of my new pieces are made of brass, so
tumbling has work hardened them too much to be able to set stones in them
later. I’ll instead do all the cleaning and finishing by hand, covering
stones up with my fingernails and buffing around them with satin wheels to
get the same look. In your experience, would running these pieces through a
polishing cycle (with wood pegs and chips as you suggest) help create a
more uniform but still satin-y texture, or is it better to keep
hand-finishing? I’d so appreciate your thoughts.

Thanks again everyone, I’m excited to work on these solutions!


Wow- so glad I noticed this post today! I have been struggling with some really filthy plastic media lately. I gave the vinegar a shot and everything looks brand new! Thanks so much for the tip.

Get the finish you want, then set stones.

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