Black slime in tumbler

Good Evening All,

I am tumbling sterling pieces in stainless steel shot using a
burnishing compound & shot I purchased via a link sent from a fellow
Ganoksin user. I have run into a weird problem that did not occur
before I purchased my new batch of shot. For some strange reason,
everything is now coming out with a weird black slime all over it.
There are some pointed pins in this shot that were not present in my
old shot. Could it be that they are scratching up the sides of the
rubber barrel If so, will it eventually stop, (as these are brand new

Has anyone had this kind of issue before? I have a simple double
barrel rotary tumbler. I have searched the forums (I seem to remember
reading something about rubber tumbler barrels before, but I cannot
find anything about it now.) Any ideas would be greatly appreciated,


I have had this same problem – both with my magnetic tumbler and
with my rotary tumbler. I remember reading that there is some kind of
a compound (triphosphate blah blah blah?) that used to be readily
available but now is hard to get unless you are a professional house
painter who has some kind of license to buy more toxic chemicals than
the rest of us are allowed to get our hands on. I have no idea what
the chemical reaction is that goes on, but I do know that in time it
subsides. I’d say the first week is disgusting and hellish, and after
that it abates to mildly annoying, and then in a couple months, I
hardly notice it. I don’t think it has to do with the rubber, I think
it’s something like the shot getting seasoned so to speak – perhaps
a reaction with the burnishing solution. Anxious to see what others
have to say as doubtless they will be more knowledgable!

Teresa: I was told to put sudsy ammonia in the barrel. In about 20
min. stop and wash it out, and put in clean ammonia. Do this 2-3
times or until clean, then rinse well. It removes grease and slime

Ruth Mary

I had this happen to me with those black rubber barrels. I believe
it’s the compound disintegrating the rubber. Try it with “Simple
Green” spray cleaner and see what happens once the shot is clean.


I encounter that when the it been used few time but after changed
the solution everything back normal and bright.

Teresa…what you are seeing is residue from either mfg. or use. You
should clean the barrel. If it is a rubber barrel, go to an
automotive parts store and get some tire cleaner. Use it to clean out
the barrel and after each use. It worked for me…Teddy

As with most things, you will get varied responses. Some people
think its the liner of the tumbler, some thinks its dirty shot, or
leftover patina from jewelry…

I’ve had something like this happen, not necessarily a slime but
everything comes out blackish, gunky, grey. YUCK.

Typically running the tumbler again - with the shot - and some Dawn
liquid (or other soft soap) will clean the shot and rectify the
problem. I’ve also heard of using coca-cola in the tumbler to clean
it but I’ve never gone that route.

I’ve only had it happen once or twice and I’ve been using the same
barrel for 5 years or so. I think, in my case, it was tumbling
jewelry that had a heavy LOS patina or doing a lot of batches in a
row that had a patina.


Hi Teresa,

I’ve seen that problem before. What I did to correct it was the

  1. Remove any jewelry pieces from the tumbler.
  2. Rinse the shot & tumbler with warm water.
  3. Add about 1 cup of water to the tumbler
  4. Add about a 2oz dixie cup of Draino to the shot.
  5. Close the tumbler & run it for about 1 hour.
  6. Remove the lid from the tumbler & dump out the liquid.
  7. Rinse the shot & tumbler in warm water.
  8. Add a little water & burnishing compound to the mix & begin to
    use again.


I have an old Viking rotary tumbler (the blue one with the cast
aluminum base and shaded pole motor, for all you geezers) and I run
non-stainless steel shot in it. I’ve been using this machine for 32
years and I bought it used. The insides of the rubber tumbler are not
coming off on the shot. That yucky stuff is the dirt and stuff you’re
tumbling off.

You have to clean your shot and the inside of your tumbler every so
often. I use a product called SR2991 made by WEBCO chemical Corp.,
but they won’t sell to individuals unless you buy like 55 gals to
clean my shot. Anyway, I use it to clean up the black stuff that
forms (most of mine is chemical antiquing that I use on silver. The
tumbler makes it look perfect. For tumbling soap I use some old
ultrasonic cleaner concentrate (Supra Galvex) that I got in a lot of
tools I bought from at auction. (I use Zep Heavy Duty floor stripper
concentrate in my ultrasonic).

I’ve been using the same stainless steel shot for years, and I never
had any black slime issues until I tried Rio’s Super Sunsheen. Once
I threw it out and rinsed the shot well and went back to powdered
tumbling soap, I never had any problems again, Sorry, Rio, just

Janet Kofoed

I get the same thing on my silver if there is any silver that is not
clean, such as a dirty casting, in the mix. I just had it happen
today with a cast silver pine cone in with other silver. I corrected
this by removing the casting and running it again with a little steel
shot cleaner from Rio Grande. I don’t think the black coating on the
silver comes from the tumbler. Burnishing is for polishing, not for
cleaning. Be sure the silver is clean before running in the tumbler.

Teresa - it is indeed possible that the slime comes from your rubber

First, let’s get rid of the slime. Right now, open a can of regular,
not diet coke. Let it sit and get rid of the bubbles. Next, drain
the tumbler with the scummy jewelry inside and rinse well. You can
even use a bit of liquid hand soap with hot water and rinse again a
couple of times. Drain it. Now, dump the can of flat coke in the
tumbler, close the lid and run it for 30 to 60 minutes. Open and
rinse until it isn’t sticky. The scum should be gone.

Now feel the inside of the barrel - is it abraded? Does it feel
smooth? If it feels ok, then likely the problem is that your cleaning
solution is inadequate. There are formulations available for the
purpose - Rio has a Sunsheen series that I find works well for me.
The only time I have the scummy problem is when I don’t use the
proper proportion of concentrated solution to the water it is mixed
with. I’ve taken to mixing a gallon jug so I get it right - mixing a
cup or two requires way more precision. I just use out of the jug of
premixed solution to barely cover the shot.

I find it easier to mix a shot processing solution when the
concentrate is liquid. Powdered stuff is just plain harder to measure
precisely - especially when the instructions are to add a spoonful -
what size of spoon? Did you level the teaspoon properly? So use a
concentrate made for the purpose. It not only cleans, it promotes
movement of the shot. Steel shot requires a different pH than
abrasive media. If you want to be a chemist and play with it - enjoy.
I’d rather make jewelry. The notion of - just use a bit of Ivory or a
dab of that may be fine - but like everything else, if you can figure
an easy way to get a good result, stick with it.

About the pins - I usually remove them from the shot. They are only
useful if you have very detailed pieces with holes or very deep
places that need burnishing. They often create problems with flat
surfaces. To remove them and maintain your sanity - use a magnet. Yes
I know that this stuff is all stainless and supposedly not magnetic.
This is how I do it. I use a magnet encased in hard plastic with a
handle - they sell them at fabric and craft stores to pick up pins.
Put a plastic bag over the magnet and drag the magnet thru the shot.
The pins weigh a bit less than the rest of the stuff and will stick
to the magnet. When you have a bunch of pins on the magnet, place the
magnet over a plastic bowl and pull the magnet out of the bag. The
pins will fall in the bowl off the plastic bag. Repeat until the
pins are mostly gone. Dry the pins and keep them in a little jar
until you need them. The trick with this is to have a magnet that is
just strong enough that’s why I use the sewing room magnet.

And if you have doubts about your rubber barrels, there are
alternative barrels made of hard plastic available as replacements.
They are usually easier to use because they have a different type of

Judy Hoch

The insides of the rubber tumbler are not coming off on the shot.
That yucky stuff is the dirt and stuff you're tumbling off. 

I agree with Norman 100%. It is not from the tumbler barrel, it is
dirt off the metal. I use Super Sunsheen and change the liquid every
run, and I have not had black gunk for 5-6 years.

John Fetvedt

I’ll bet your slime is left over patina from pieces that have been
tumbled. In a patina experiment of mine, I managed to get my
stainless steel shot gunked up. Every batch of silver now comes out
somewhat tarnished (yellow) but it is getting less so with each
batch. I put Dawn in each time, so it is probably washing the stuff
off the shot slowly. I don’t worry too much about it, I just dunk the
finished silver in an acid jewelry cleaner and it comes right off.
However, I can no longer use my tumbler to get rid of tarnish as I
once did. I guess it’s time to try some of these suggestions for
cleaning it up.

Sun Country Gems LLC

Whenever using new shot [stainless or steel] always run it several
days, changing the soap and water several times and finally rincing
well -without any product in it. Even adding a very small amount of
fine valvegrind paste to the water for the 1st few hours can help,
but it must be very well rinced in hot water afterwards. cjh