Jeffrey, I suggested tumbling for hardening. I do it all the time
with no damage to the wire. I use steel shot, and Ivory soap. I get
a bar of Ivory soap, grate it (using the fine grate), and use it for
all my tumbling. It works just fine. Usually I grate the whole bar,
and store it in a jar, so that I always have it on hand. I have a
very small tumbler, and usually use a heaping teaspoonful of the
soap. It usually does the job in about 30 minutes or less. For larger
tumbler you will need more.
When you get the Ivory soap, it is very soft, so, I usually unwrap
it, and leave it to harden. It is easier to grate when it is hard.
However, if you are pressed for time, you can grate the soft bars.
I am always surprised when I hear people tumble their things for
several hours. Often they complain about pits. I think they are
tumbling much too long. I find that 30 minutes is ample. That is all
I use for polishing my metal, or for hardening. Retrieving small
items—especially 8 mm pins, can be a challenge. I just pour the
entire contents of the tumbler into a fine mesh strainer, where I
can then easily pick out my pieces. Often I save the sudsy residue,
put it back into the tumbler with the shot. It protects the shot from
rust, and saves my having to dry it every time I use it.