Grey scum on copper pieces after tumbling.

by Jane
(British Columbia, Canada)

I have just started using copper with my lampwork beads, and when I tumble the pieces I get a grey scum in all the crevices, which I have to brush out with a brass brush. It is very time consuming, and I can't always get it out due to some of the designs. I am using a Lortone 3A tumbler with steel shot, water and shaved ivory bar soap. Do you have any insight into my problem? Thanks!
Your pieces are absolutely stunning, and I hope to own one of them one day.

Jane P.

Stacy's Answer:

Hi Jane!
I agree with you that having to hand-polish your copper after removing it from the tumbler would be very time consuming and a pain! First off, I would change the soap that you're using to tumble your pieces in. Here in the States, we use Dawn dish soap, but you can probably use another liquid dish soap, as long as it does not contain any perfumes, dyes, abrasives, etc. You should not get a "grey scum" on the copper! Try running your tumbler with only Stainless steel shot, a squirt of dish soap and enough water to cover say 1/2 inch over night to thoroughly clean your shot and the rubber tub.

I've written an article you can find here,, in the "Articles Section" that discusses in some detail all you may wish to know about tumbling. (you'll need to sign up, but there is no cost and I think you'll really enjoy the site!)

Please let me know how is goes!! Thanks for your question!
Happy wiring!
Stacy :)

Comments for Grey scum on copper pieces after tumbling.

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Jul 02, 2009
Grey scum on copper
by: Jane

Thanks Stacy,
I have already run the tumbler with just the shot, water and soap - in fact I did it for two days. The water was quite dirty after the first day, so I changed it, washed the shot, and ran it again. I am going to try changing the soap, and hopefully that will help.

Jul 06, 2009
No more grey scum!
by: Jane P.

I have done several experiments, and the results are that I have now changed from shaved Ivory bar soap to the Dawn blue liquid - and presto, no more grey scum. I guess the combination of my water, LOS'd copper and the Ivory just was not a good one. The Dawn has made all the difference.

Oct 26, 2010
grey scum
by: heather

I've scrubbed out my drum, used dawn, have tumbled my shot alone with just dawn for over 48 hours - switching the water every 8 or so, and i STILL get the grey scum. The only thing that removed it is sandpaper. Any ideas??

Oct 27, 2010
Grey Scum
by: Stacy

Hi Heather! The "grey scum" could be dirty residue being removed from your stainless steel shot. Or, it could be just the dye leaching from the rubber as some rubber has a tendency to do until it becomes more "seasoned." Or, it might be something else entirely. Whenever I tumble my shot for a couple of days, I also get water that's no longer clear!

I'm curious as to how the sandpaper is removing the grey residue? Where exactly is the residue you're talking about? Is it on the jewelry itself or is it the color of the water? The water/Dawn mixture is supposed to turn grey as "stuff" is lifted off the items in the tumbler. What does your jewelry look like when you remove it from the machine?

48 hours seems a very long time to tumble something with or without refreshing. To remove any crud build-up from the rubber barrel, only use a soft cloth and sudsy water...nothing abrasive as that can damage the rubber, causing it to slowly disintegrate.

I do not use the tumbler to polish everything. Sometimes my flexshaft with appropriate polishing bits or a buffing machine are a better way to go. Even after tumbling, I usually still give things a finishing polish by hand with a jewelry polishing cloth.

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