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Silver corrupted by aluminum


#1

Hi All,

Just a curious question from a student…

I have two pieces of silver that have become inadvertantly
corrupted, with aluminum in one case, and some sort of base metal (my
profs say it’s “alpaca” - translation thing…) and I was wondering
if anyone had any suggestions on what kinds of fun little experiments
I could do with them. I’m far too curious (and cheap) to let it just
go to waste and not play with it, so I’m wondering if anyone has had
this experience before and what the results were.

The first mix, with the base metal, I got from accidentally melting a
base metal earring in with my silver; I knew something was wrong when
it wiggled slower than fluid silver normally does… But I kept on
going as it was 20 grams for wire for a project. I had the most awful
time pulling it! I made a bunch of twisted barbed wire pieces which
have enough movement for the bracelet and I’ve been able to solder it
together with good results, but what a tricky job! Even though it’s
still mostly silver, it still has the capacity to just “droop” if it
gets too hot, and if I pick it up with pincers while it’s still too
hot (whatever temp that is…) it just sort of squishes and falls
apart. On the plus side it’s rock hard when cool enough, so I’m
thinking my bracelet will never have problems with its links! But I
have no idea how evenly it’s mixed, so I’m having a real fun time
soldering it… But anyway it makes me really curious about creating
a sort of “moon surface” pendant by strategic squishing or
something… Have any of you had the same experience, and what you
did with your happy accident?

The second is a mold piece of PMC, where I had embedded aluminum in
the middle during a “how can I make PMC explode?” experiment. Our PMC
prof had brought in a piece where a PMC mold of a head accidentally
exploded the top of the head open (she called it “migraine”, it was
brilliant!) - but she had no idea how it had happened and
experimenting commenced… So I now have silver with some aluminum
jammed in the middle and I don’t know what, if anything, I can do
with it. At least I feel pretty safe with the base metal, but
considering I put these two together to try and make it explode to
begin with, even melting it down makes me a little nervous… Anyone
ever run into this before? Or do it on purpose? Make anything cool
with it?

I really can tell the difference, but I took two loner earrings off
a lady who I thought knew the difference between silver and costume,
and didn’t really look at them closely before adding them to the
melting pot - definitely learned my lesson!

Well, any ideas or fun experiments that don’t involve trying to
chemically separate them would be greatly appreciated! For that
matter if you have any other tales of happy accidents and experiments
where you accidentally added the wrong metal to your mix and came up
with something cool…

Cheers!
Liz


#2

You can dissolve the aluminium in sodium hydroxide solution and this
will leave the silver untouched. As for the base metal/silver mix,
then you need to acquire a cupellation dish. these are shallow
refactory dishes that have a lot of bone ash in them and they absorb
most base metals like tin, copper etc. Heat the metal with a hot
flame but dont flux, you can sprinkle a little carbon on top to
reduce oxidation. You should end up with a bead of silver. Only use
the dish once. if you weigh the metal before and after, you have just
done a simple assay as well!

Nick


#3

Hi Liz,

I have rescued contaminated gold and silver using an oxy/acetylene
cutting torch. I use the preheat part of the cutting torch (with
multiple holes) for all melting jobs without using the big center
cutting hole.

I have found that if I get the gold or silver molten and then press
the trigger to inject oxygen through the big hole as in cutting iron
and steel, the melt will sputter and get very hot due to the base
metals actually burning off.

The oxygen pressure has to be set higher for the cutting part to
work. When only using the preheat part I set the oxygen and acetylene
to equal pressures, but for cutting (injecting oxygen) the oxygen
pressure must be higher- follow the instructions on your equipment.

Anyway, the rare bar that cracks or crumbles when rolling has been
cured by the above method. The final purity will be unknown because
all base metals will be oxidised and burnt off to some extent; what I
do know is that the resulting bar will be a higher purity than when I
started!

Alastair