Tumble Polisher Keeps Going Black

Hi everyone
wondering if you can help. I have the small 2lb tumble polisher from cookies with mixed shot and barrelbrite. I've had it over a year and never had any problem with it until christmas, then I went to polish some items, and they ended up coming out scummy, like they had a dirty coating on them. I cleaned out the barrel completely, cleaned all the shot and replaced the solution with fresh and it was fine. I haven't used my tumbler since then, but then when I went to use it again today the same thing had happened.
Does anyone have any idea why, and how I can prevent this, as it ends up me having to pumice clean my piece the get the 'scumminess' off.
I don't put any pieces that have been oxidised in it, so I don't know why this is happening :(
Any help would be appreciated
Thanks

Hi Laura,
You don't say what metal you are polishing, but when copper comes out of pickle it has a loose deposit which can be transferred to silver if it is not cleaned off first. I have also fond that copper can become much darker if not removed from the tumbler and rinsed straight away.

I have also heard occasional grumbles about Barrelbrite, so you might try using another soap, such as the cheapest washing up liquid, which does not have much fragrance added. Dennis.

Just to say that Barrelbrite contains a rust inhibitor and some washing up liquids contain bleach so you have to be careful

Hi dennis i only ever put silver into it, but it seems to come out with a scummy coating and the inside of the barrel is black. It was also weird as the barrelbrite didnt foam up like it normally does. I used same solution of barrelbrite for months before, but this was a fresh solution made at xmas, but from the same batch so i'm confused

Well Laura,
It looks as if you will need to do some more experiments, perhaps using a few pieces of silver scrap, or an old unwanted piece that can be reheated and re pickled as necessary.

1.If your barrel is made of plastic and the shot is stainless steel, then it can only be the fault of the barrelling medium. Changing to something else would prove that.

2.If your barrel is plastic, but your shot is ordinary steel, the steel could have become corroded and would need a prolonged polish on its own.

3.If your barrel is made of rubber and old, it could be past its life and perished leaving a deposit of rubber.

Only doing the experiments with just one ingredient changed will solve it, but we would all like to hear the answer. My money is on the soap. Dennis.

Thank you Dennis, I'll give the experiments a try with some scrap. I did remember though that the last item I had polished before it went scummy was a pendant with a claw set tumble tigers eye. I had just bought it from a museum, so it was a rough untreated stone and I just left it like that. Could this have contaminated my tumble polisher?