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Melting scrap silver


#1

Hi, I’m trying to recycle my scrap sterling silver. Think I read
somewherethat you should add some fine silver, is that correct and
if so how much ? What difference does it make ? What happens if you
don’t ? Just want to make some thick square wire to try forging a
bangle. Any tips welcome.

I’ve read some amazing stuff on here about metals so I’m sure
someone will have good advice.

Trish. UK.


#2
Think I read somewherethat you should add some fine silver, is that
correct and if so how much ? What difference does it make ? 

This question can have several correct answers. Safe way to do it is
to add 1/2 of the amount in fresh metal. It will guarantee good
results every time. That said, it is possible to reuse the same metal
over and over again. Depends on flux composition, smelting skills,
and purity of metal to start with. Also forging of ingot can make a
difference. It is not easy to explain why it is so. Some common
substances like sulphur, carbon, and silica are always present during
smelting. They can form metalloid compounds which are brittle. It
does not take a lot of them to render freshly cast ingot useless. The
success of reusing metal lies in control and prevention metalloid a
from forming.

Leonid Surpin
Studioarete.com


#3

Hello Trish,

If you are casting with your scrap, then it is good to add an equal
amount of ‘new’ sterling to the mix.

I don’t cast - but I use up my scrap sterling by making accent
balls, which are fused or soldered onto other pieces. I also use the
scraps to overlay and enhance the beads I make. They’re kinda’ funky
and never the same. More fun that way. My scrap bowl is an unending
source of new ideas.

Judy in Kansas, where the snow storm in Denver is going to bring
colder temps here. Time to cover those tender plants. sigh.


#4

if its all sterling scrap and clean (use a magnet over the scrap to
make sure there are no sawblade bits etc,) in the lot, You do not
have to add clean casting grain, .925 or .999 of the material you
are melting isn’t full of solder remnants (scrape anything that
doesn’t come off in pickle with a bench knife or cut it off with
shears and don’t use it if burnt).

remember to melt the .925 with a generous pinch of boracic
acid*/b*oric acid in a well borax glazed dedicated crucible. Warm
the mould well before pouring to avoid thermal shock.

I use a bit of refining flux if necessary, but if you have very
clean scraps its not needed (recipes in archives).


#5
This question can have several correct answers. Safe way to do it
is to add 1/2 of the amount in fresh metal. 

[snip]

The success of reusing metal lies in control and prevention
metalloid a from forming. 

Excellent, answer.

As an alternative you can remelt your alloys in a furnace this can
give a good result as opposed to melting in a dish crucible. Removing
dross and impurities is easier when you use a furnace.

Having a clean furnace, and in some cases using a crucible with a
lid can make a great deal of difference to the purity of a melt.

Regards Charles A.


#6

Good timing, Trish. I was just about to ask the same question. My
scrap silver is not clean. I have a very large amount of Indonesian
beads and findings I bought 10 years ago that I would like to melt
and turn into sheet. Can I assume it is loaded with solder due to
the prolific granulation and decoration? If so, should I send it to a
refiner instead of trying to melt it and alloy it myself? I have a
little experience with melting since I used to do my own centrifugal
casting, but only with casting grain. I have never tried alloying.

Thanks,
Kelley


#7

Thank you all for such good on melting scrap silver. My
scrap is all sterling with a bit of fine silver very little solder.

I just want to make good use of my own waste silver and learn and
understanda bit about how the metal behaves. I have quite a bit but
not really enough to send to a refiner.

Silly question but how Is boric acid different from borax? Leonid you
have answered my questions about how the metal reacts to being
melted, I’m sure it is a very complex process that I stand little
chance of controlling.

I want to try forging a bangle and thought I could practise by using
my scrap. The bangle will not be sold but I want it to be perfect of
course. You are all amazing here at orchid I’m learning so much from
you all.

Thank you
Trish. UK


#8
Silly question but how Is boric acid different from borax? Leonid
you have answered my questions about how the metal reacts to being
melted, I'm sure it is a very complex process that I stand little
chance of controlling. 

Process may be complex, but as goldsmiths we do not have to
understand down to molecular level. Flux is an integral component of
melting, so it make sense to spend some time discussing it.

For melting silver neither borax, nor boric acid are suited.
Adequate flux is sal ammoniac. The best flux has to have additional
components, based on particular circumstances. Generally, the
dirtier the metal, the more complex flux recipe should be.

There are 3 main enemies standing between goldsmith and sound ingot.
They are - oxygen, flux acidity, and common impurities like iron. Sal
ammoniac, at high temperatures will decompose into ammonia and
hydrogen chloride, both powerful oxidizing agents. They will form
oxides that will rise to the surface. Also by-product of reactions is
free oxygen. Use too little and not all of the contaminants will be
removed; too much will result in free oxygen been present, which is
detrimental for silver. Oxygen can be converted to carbon dioxide by
introducing carbon, which is accomplished by addition of flour.

Oxydes has to be contained in some kind of a medium. Borax can be
used for this purpose, but regular soda is far superior. Soda also
neutralizes acidity of flux. It acidity is not neutralized, some of
metal can be trapped inside molten flux, a condition some of you
most familiar.

Iron will be present, no matter what you do! Working metal with
magnet only reduces amount of iron.Complete elimination should be
done in crucible by adding potassium carbonate. One more component
to finish the recipe is powdered glass.

Presence of glass makes flux to retreat to back end of crucible
during pouring. That way one get ingot without flux been trapped in.

Needless to say that working with chemicals is dangerous and can
cause serious injury. Good ventilation is a must.

Leonid Surpin
Studioarete.com


#9

Hi Patricia,

I save up my lemel (scrap silver) sheet and wire and use it to make
bangles and pendants.

Why send it a refiner and get back less than you paid?

For a bangle place silver pieces to about 15 mm wide on a soldering
block and fuse it together, lay out more than the length of the
bangle. I heat it till it fuses together. I get about a 3-4 mm thick
uneven strip of metal Now the fun put it on steel block or anvil bash
it down to 2 mm thick. Use a 2 pound mallet cheap from a hardware
store. This is not precision work but great fun.

You now have a strip of silver that is roughly 2 mm thick and uneven
shape on the edges.

File the edges, anneal and quench in pickle.

Bash round a bracelet mandril overlap and cut through and solder.

True up again on mandril, clean up and polish.

You know have an odd shaped bangle. It is unique and unusual, and
something your customers will not have seen. And you can charge full
metal price and the metal has cost you nothing, lemel my favourite
word.

To get even more exciting take hammered strip and reticulate, file
down one side and clean up the edges make into bangle. Use leather
mallet to hammer reticulated strip round mandril.

Watch closely as reticulated sterling can be brittle.

Polish inside of bangle, file edges to give a frame to the
reticulation.

Anneal and scratch brush 3 times.

Now you have a bangle with a reticulated surface but a smooth
polished inside and polished edges.

And you will have learned a lot about how sterling melts and
hammers.

Use your imagination and this can be a very profitable way to turn
lemel into stock.

Have fun.
Richard


#10

Hi Kelley

be very careful if you melt Indonesian silver. This stuff is
basically an unknown metal fineness.

Forget the fineness marks, they are a myth in Indonesia. Just looked
at some Bali sterling today, why is it a grey colour? Because it is
800 fineness or less. Clean up one of your pieces and put it next to
known sterling and check the colour difference.

Send it to a refiner and get back the metal you want. Expect a small
return on the metal.

I have a friend who specialized in repairing Indonesian jewellery,
because no one wanted to touch it. She made a lot of money doing
repairs until playing with crap metal just became too boring.

The last stone I removed from a Lombok made ring was held in with
hot melt glue and the metal was thin and very brittle and a nasty grey
colour, fineness mark 925, LOL.

It will not melt down into quality sheet no matter what you do,
unless you are an alchemist.

Just send it to a refiner and save yourself grief.

Richard.


#11

the finess on the Bali sterling chain, I had assayed came in at
525-550 parts silver, even though it was stamped 925.in the 1900’s
the place of employment was getting byzantine chain from Bali it was
soo cheap/and grey/poorly made, so tried to get it made by the kilo
in the mid east at sterling level it looked beautifiul but was 3
times the price. after that started checking everything that came
from outside the US or Europe. 550 silver is fine but at least let
the client know or stamp it as such.

Hratch Babikian


#12

Ok… I’ve been self teaching for two years, and mostly using and melting down my moms marked sterling sliver flat ware… (no body was interested in buying cuz boring design)… I even sometimes just anneal the fork tines and directly make wire or sheet, as well as using other parts of the utensil like flatten the spoon and directly roll them flat, without melting to make ingots, is that wrong? My mother sold all her jewelry thinking she’d won millions, in a scam to pay taxes on her supposed winnings! Let alone gave the scammers thousands and thousands… I want and WILL use this silver, just cuz there is nothing left from her or my dads jewelry, cuz she sold it all!
Ive only had success so far… It’s been for practice, not selling. But I want to use this silver, leather when I sell my jewelry cuz I have lots, and it’s 925! What do I need to do to make it safe or proper for selling my jewelry? When I do melt it, I do it probably with a borax coated , and sprinkler more borax in while it’s melting. Thanks!! Mimi