Black residue on tumbled jewellery

I have black rubber tumbler which so far has not been depositing the
compound on jewellery yet but I have found that on occasions I have
inadvertently put some pieces in that are not silver i.e., copper or
steel, this then leaves a black residue on the other material.

The tumbler then has to be thoroughly cleaned before returning to be
tumbled again.

John Wallace

My solution for black residue has been to use two sets of two white
tumblers. The first contains the Rio Grande clean cut plastic media
and I use deburring compound solution in those. The second set
contains stainless steel shot and I use Rio’s burnising compound for
those. When I use a patina or the silver is quite tarnished, I begin
with the first set of barrels and change the solution if it becomes
dark and black and continue in short units of time until clear. Then
I transfer the silver pieces to the stainless shot and tumble as
needed for polishing.

The burnishing compound is not a cleaning media. The deburring is a
cleaner. Perhaps the black grease stuff could be dealt with by a two
step process. It has solved my problem very well. I do have to clean
my steel shot with ammonia occasionally. I’m tempted to try Judy’s
Coke method as well.