Finishing metals in rotating tumbler
BayuBijou
I make chains and chain maille (sterling and GF so far) and have been
finishing/polishing them in a rotating type tumbler, but have a couple of
questions, due to a couple of apparent errors on my part. I'm using the mixed
shape steel shot and Rio's Super Sunsheen Burnishing Compound.
a) Should I not be mixing metals in the same batch?
b) Is there a minimum time to do the tumbling so that all edges are smooth and
everything comes out nice and shiny?
c) What is the maximum time that I shouldn't go past?
The problem I've encountered is that once I had both sterling and GF pieces in
there and when I took them out they looked really "yucky". I can't recall how
long I left them in that time. Another time, I only had one GF piece in there
and I had to go out, was gone longer than expected (several hours) and when I
came back, the burnishing compound had turned a very very dark grey and there
was a greyish color film on the metal. Both times, when I changed the
burnishing compound and retumbled them, they came out fine.
Not sure if the mixing metals is a problem, but obviously the 'time' is...I
just don't know what the limit should be.
Any insight is most appreciated,
BB
Charlie Fred
snip
>a) Should I not be mixing metals in the same batch?
>b) Is there a minimum time to do the tumbling so that all edges are smooth and
>everything comes out nice and shiny?
>c) What is the maximum time that I shouldn't go past?
Do not mix metals. Generally, your silver will take on a gold 'cast'.
Tumbling time depends on the rotation speed. The rotary tumbler that I
use (I borrow it from a friend) will burnish silver to a bright finish
within an hour. It is home made and has a fairly fast rotation rate.
Within a couple of hours the sharp edges and fine details get rounded
over.
Notice that I said burnish. I have seen some jewelry that looked
highly polished. Close inspection revealed major scratches on the
pieces - but they sure did shine!
Charlie
Charlie Fred
Johnny1959
I'd been wondering something along the same lines recently (mixing metals).
If the above is the case, do you have any suggestions about something where the
finished piece is mixed metals? Do you just chance it and hope it comes out
okay? Not let it tumble as long? Or is there something that can be done
afterwards that would take the gold cast from the silver, but then not affect
the silver?
Alberic
The greyish "crud" that showed up on your pieces is probably due to either
too much sunsheen in the mix or letting it run too long. I'm presuming
you're running in a black rubber (neoprene) barrel. If you put too much
burnishing compound in the water (or let it run too long) the compound
will start to eat into the neoprene, causing that greyish crud to appear
on your parts.
My usual solution is to cut way back on the sunsheen. (1 cc per big
barrel load.) There's a fine balance here, so just experiment, but try to
err on the side of "less", and it'll work better.
Hope it helps,
Brian
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To Email me: there are no numbers of any sort in my real address.
Jeffrey Bromberger
So do I, so this is very familiar to me...
>b) Is there a minimum time to do the tumbling so that all edges are smooth and
>everything comes out nice and shiny?
I'm using a small Lortone (1.5 pound) tumbler, basically made for stone
work. In fact, it is used for rocks more often than I do for silver!
Generally, I let the silver pieces run overnight. The small bottle of
mixed stainless shot puts an inch and a half of steel at the bottom of
the drum I use. The Sunsheen comes up just to cover the top of the shot.
It's the same technique you use when polishing stones. So I slop in
the silver (either in chain form, or raw jump rings strung together on a
copper loop) and let 'er rip overnight. The noise doesn't bother me,
and I have enough going on that this one day delay in production does
not hinder me at all. If I was doing one chain at a time, then there
would be a real timing problem!
>c) What is the maximum time that I shouldn't go past?
I figure that 8 hours is a maximum. See below for a reason.
>the burnishing compound had turned a very very dark grey and there
>was a greyish color film on the metal. Both times, when I changed the
>burnishing compound and retumbled them, they came out fine.
My compound turns a dark (almost smokey) color within an hour of use.
When I look at the stuff under a microscope, I can see that it's picked up
tiny chips and flakes of silver and the tossing action keeps it suspended.
The chips probably come from the rough ends of the pieces - I get more of
the silver flotsam and jetsam from cut rings than from finished chains.
I never use the media to remove things like fire scale and oxidation from
my chain work (there's a pickle vat for that). There must also be small
pieces of the drum rubbing off as well, but these pieces are way too
small for me to see. I have yet to really "flush" the burnishing shot
and drum. I just keep adding new solution to the drum, enough to keep
the shot completely covered. Most of my loss comes from froth sticking
to my fingers and the liquid held in the chain links via capillary action.
I have never quantitatively figured out how much silver I actually
lose from this burnishing method. I'd be really freaked out if I had
to leave stuff longer than overnight. The amount of silver hovering
in the solution makes me believe that the steel shot is very
aggressive when it comes to removing silver.
This is all from my personal experiences. YMMV, of course.
j
--
Jeffrey L. Bromberger -- Senior Systems Administrator -- Tramway Systems
jef...@tram.com ---- jef...@liii.com ---- +1.212.208.3616
PGP 2.6.2 Public key available upon request http://www.tram.com/~jeffrey
Marion Margoshes
Fishbre396
<m...@panix.com> writes:
> What is sunsheen and where do you get it?
Rio Grande sells it . . . it is a solution used for tumbling with stainless
steel media.
babe
cutting media or steel shot. A less aggressive and better finishing
material is ground walnut shell or shell charged with rouge. Ground corn
cob works very well too. I overran some silver this past weekend. (As I
forgot to turn off the vibrator and it ran through Labor Day.) The
results were astounding! The silver was finished to a brightness and
smoothness I have never seen before. I was using rouge charged walnut
shell with a very small piece of red bar rouge as an abrasive
replenisher. I had some chain, rings and bracelets in the unit. All were
some of the best finish I had ever seen. Total run time was about 100
hours.
Will
Better Alloys - Better Engineering