Back to Ganoksin | FAQ | Contact

Copper Surprise!

I made some pretty copper rings and thought I’d shine 'em up. I put
them in the rotary tumbler with the steel beads that do such a good
job on silver. When I took them out a few hours later - surprise! -
they were a uniform dark brown color inside and out. Kinda pretty
actually but not what I had in mind.

I’m new to working with copper so I thought maybe you copper
afficianados might have some ideas about what is happening and what
best to do to get a nice finish.

If this has been beaten to death already just tell me and I’ll go to
the Archives.

John in Indiana

John Moe
Pentaluna Jewels

I always use a little dawn in my tumbler (tiny bit) and I never have
copper do that. I’m befuddled. I don’t have an answer other than
clean your shot and barrel and try that?

i did not see the original post, but it sounds like copper is getting
dark in a tumbler. when my tumbler was new i had the same
issue…clean out the barrel with some dish detergent before use. i
always use a bit of detergent when i tumble as well. it may take a
few runs or cleanings before its completely clean…but it should
clear up :slight_smile:

I’m SO curious about the answer to this question. I clearly did
something very bad to my tumblers last winter. I have since cleaned
them, changed them, in one instance exchanged the shot entirely, but
i have no idea what went wrong. All I know is that after having
tumbled some bronze, everything went haywire. The bronze looked
awesome, but the next silver batch I did (after rinsing/cleaning)
came out looking like pink gold. Awesome! Except… huh? And it kind
of wore off on the skin. Not so attractive. I suppose bronze is
probably just a gigantic nono but now that I hear this question asked
about copper, I wonder if it was the copper that made all go wrong?
Should I just only tumble silver and gold? What’s the determinant and
what the hell happened?! Thanks so much! Love the mysteries of
chemistries once they become beknownst to me.


Clean your shot and try again.

I tumble copper all the time. 20-30 minutes with Super Sunsheen from
Rio Grande is usually enough. I’ve tried Dawn and other suggestions
and never gotten as good results as I do with Super Sunsheen. Be
sure to rinse and change the liquid every half hour or so if you
tumble then for a longer time. Otherwise you end up just grinding the
dirt into the surface of the rings.

John Fetvedt

I tumble copper frequently. Clean your shot. You might try pickling
your rings again to get rid of the dark brown then tumble them again.
Whatever you do, get rid of the dark brown before re-tumbling. In my
opinion, this is not a copper problem because I’ve had it happen on
silver also. I’d guess that had this batch been silver you’d have
come out with a dark grey cast to your silver.

Dick Ah Mexico! Where “C” on a faucet means HOT, and “M” on a restroom

Hello John,

I commonly tumble mixed metal pieces (sterling and copper) with
stainless steel media. The pieces always come out quite shiny, but
it only takes 30 minutes or so. Did you add some low-sudsing
detergent? If so, check the ingredient list - some components will
patina copper.

Judy in Kansas, where it’s really chilly and the furnace is running…
just a few days ago temps were setting record highs of 99+

Hi John,

Some detergents will do that to brass or copper. But copper is a
pretty reactive material, so it could also be a contamination of some
sort. If you repeat the process being very careful about cleanliness
and it happens again it is most likely your solution isn’t suitable
for copper. If you repeat the experiment and the it comes out clean
you probably just had some kind of contamination.

For many years I tumbled mixed metal jewelry that contained copper.
This has happened to me now and then, but probably less than 2% of
the time, so I would assume it is some kind of contamination rather
than the materials. Fix it by pickling and repeating the tumbler
cycle with fresh solution.

Stephen Walker

Andover, NY


My shot is clean - I hadn’t used the tumbler since the last time I
took the shot out and washed it. I am glad to know that it can work
for polishing copper so back the the drawing board. I’ll dump the
shot out and clean it again, then lay it out on a pizza pan to dry.

John in Indiana
John Moe

I had the pink-gold problem with brass and someone replied about a
mixture of ammonia and peroxide. I don’t the the proportions here,
but they’re in the ganoksin history. It really works.

Personally, I have never tried it, but I remember collecting this
comment from, Barb, a brass hardware manufactor in New England when
I put together this article on Tumbling years ago. She used oil to
cover brass parts in steel shot.

  In our joint compound, plastic pail tumblers we use steel shot
  and mineral oil. those tumblers have 2"x 1.5" high wide wooden
  paddles mounted inside diagonally from the bottom to the open
  end. One is all, I think. That works well too, they have to go
  really slow or they spit shot at you, and they cannot be
  tilted down to empty, due to the nature of the design and the
  lack of weight that a plastic bucket can support. We used
  covers with large shot (.080+) because of the flying shot
  problem but don't need it with the tiny shot. We reach in with
  a homemade rake and get the oily parts out. Shot is heavy and
  we don't want to dump it anyway. 3 barrels are linked together
  and 2 others work together as they are small and we needed
  more capacity but didn't want to spend money for real
  tumblers, plus we used old motors and pulley reduction devices
  that were laying around to make them. Most tumblers are on
  timers, but some are light switch type. 

The rest of the article is at:

I find that certain drums have more sulfur in them than others. One
friend had a new drum that’s practically unuseable, even after
extensive cleaning…it stinks! Literally. I have it now since I
can’t smell very well, but I only use it in the garage so as not to
offend my students.

Every now and then I have a copper/silver interaction, but for the
most part, I can tumble both metals together. I use stainless steel
mixed shot, with a splash of Dawn dishwashing liquid as my burnishing

best regards,

I'm SO curious about the answer to this question. I clearly did
something very bad to my tumblers last winter. I have since
cleaned them, changed them, in one instance exchanged the shot
entirely, but i have no idea what went wrong. 

Try using proper shot cleaning soap and proper tumbling soap.

Tumbling metals generally comes out nice, but if the shot solution
is old and gray, or the metal to be tumbled is really dirty, you will
have dull, blackened work. I have old carbon steel shot that is over
25 years ol that I’m still using, but I have to make sure to clean
it every so often with shot cleaner, sometimes twice, before I use
the tumbling powder. I have to use 910 or 920 tumbling powder from
Rio Grande,

simply for the rust inhibiter and it is good for 2-10 cycles before
changing. Any metal that needs to be tumbled, should be cleaned using
Tarn-X or something to remove any tarnish, and if it really greasy,
some Simple Green will degrease the metal. I have a student, for
whatever reason, would get my shot solution very dirty in no time,
even with clean 920 tumbling solution. I find I have to constantly
clean my shot whatever she’s using my tumbler. Sometimes twice during
the day. Even the barrel needs to be cleaned out with a degreaser and
the shot degreased as well.

On another vein, a jeweler I used to know, had a habit of throwing a
small lump of pure gold in her tumbler to tumble her silver chains,
and the silver chains would come out a luxurious golden color. That
could work if you want the beautiful golden look.


A pizza pan? An aluminum pizza pan? Hey you chemists out there,
could the shot become contaminated with the aluminum? Would that
make any difference?

I am really cautious about what metals I use in my shop, stainless
steel is ok, but I don’t use any tin, zinc or aluminum.


Forgot to tell you, when using Coca Cola to clean you steel shot,
make sure you use the regular kind, not the sugar free one. Sigi

Clean your shot with Coca Cola, tumble for 10 minutes, then rinse
with clear water, and use super sunsheen in your next job, it always
works for me.

Good Luck Sigi