I was recently asked to recommend a process for achieving a soft
matte finish on handmade sterling chains using a rotary tumbler. As
I’m not an expert in the area of mass finishing, my first instinct
was to hit the Rio catalog, buy a selection of media, and start doing
experiments. Then it occurred to me that I might be able to get a
jump start on the experiments by posing this question to the Orchid
group and learning from the group’s collective experience. If anyone
has any ideas of where to start (or what to steer clear of), I would
be very glad to hear them. My initial idea was to burnish to my
normal high shine to get a very even, consistent surface and then do
time/grit size experiments with simple silicon carbide abrasives,
perhaps using plastic pellets to provide some bulk in the tumbler.
If the SiC proved unsatisfactory, I was then planning on moving on to
the various proprietary abrasives…a somewhat bewildering idea,
given the array of choices available.
Diamond Pacific carries a product called Vibra-Dry. Their new
catalog has a page dedicated to its use.
Some years ago, the inventor, Ed Smith was demonstrating this in the
Diamond Pacific Tent in Tucson during the big show.
It is impressive and is used dry.
I am currently using it on fabricated, finished sterling and stone
pendants I have made. In setting the bezels at times I have managed
to mar the stone, or have gotten residue from finishing on the stone.
Putting it through first 25,000 and then 50,000 grit. I may be
restoring the stones and finishing the piece.
Tom, I don’t know if this will give you the matt finish that you are
looking for but I cut the shine on silver chains by folding a piece
of steel wool around the chain and pulling the chain through it a
couple of times. I use 00 steel wool.
If you are after a sort of shiny matte finish, you may want to see if
you can borrow some time on a magnetic pin finisher, and try that on
the chain.
Something else that comes to mind (and would be very simple)is a bead
blaster. I would hate to have to do this on a high volume production
run, but the results are very nice, and very predictable.
Rio has some very nice table top units for under $200.
The best matte finish I have seen is to tumble item in plastic
media, tumble with steel shot, then re-tumble in plastic media. Looks
like what high end jewelry with matte finish looks like.
It would be better if you had a small vibratory tumbler, but lacking
that I’d use any of the medium ceramic abrasives. All of the tumbler
suppliers have some variety of it. The ceramics are heavier than the
plastic ones. Just run your chain in the abrasive - 6 to 8 hours in a
vibe and 18 to 20 in a rotary - checking periodically to make sure
you have sufficient liquid. At the end of the process, you will have
smooth lovely matte finish on your chains. There is no need to run
steel first unless you need to work harden the chain.
If you are running several chains, I’d really suggest getting a
vibratory tumbler, because the rotary ones tend to tangle chains.
And here’s the pitch - there is a book on this subject “Tumble
Finishing for Handmade Jewelry” available from all the major
suppliers - Gesswein, Rio, Otto Frei and others. Get a copy and your
life will be simpler because the stuff about mass finishing is pretty
well documented in it. It gives you product names, times, media
recommendations, a cookbook for times based on metal, finish needed,
etc. I’m biased, I wrote it.
tumble item in plastic media, tumble with steel shot, then
re-tumble in plastic media.
Why the steel shot between to plastic media tumblings?
Having done it both ways, the look of the finish using steel shot and
then re-tumbling with plastic media gives a cleaner brighter finish.
Without the steel shot the best I can describe is that silver has a
dirty gray look. If you try it both ways, let me know if you see a
difference. I was producing some work for a couple who were doing
craft shows,and they had me cast their custom sterling beads. They
wanted a matt finish, and the beads were patinated and then tumble
finished, and with out the extra step the pieces looked gray. They
just did not look good to me. The actual way I discovered that steel
shot improved the look was that they wanted some high polish pieces,
and then they wanted them matt finished when they saw what they
looked like. Serendipity.