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Is it sterling or not?


#1

I am a mostly self taught metalsmith and have been enjoying the hobby
for a number of years now. This spring I decided to take a class at
my local art school just to find out if I was doing things the proper
way or did I need to change some of my habits. Fortunately, I learned
I was doing pretty well.

I asked my instructor one evening if I could melt down some sterling
silver into plate. I had been given a number of castings that a
friend had done several years ago and never completed the project.
They hadn’t even been cleaned after coming out of the cast and still
had the sprues intact. My instructor told me that I could melt them
down but they would not be sterling silver any more. Now she is a
recent graduate and maybe not the most expert jeweller in the field
so I’m cutting her some slack. But, is this true? If I melt down
sterling silver straight out of the casting machine, make it into an
ingot, roll it out to sheet stock, make not alterations to it at all,
how can it not be sterling silver?

I realize that if I melt down scraps of silver from making projects
that may have bits of solder etc. on them that it would not be
sterling unless I added casting grain, but if it’s just straight out
of the cast, does it need casting grains to be called sterling
again?

thanks
Dianne


#2

If everything that you melt is at least 925/1000 silver, then the
result is Sterling (in the USA). You could then stamp it as such.

John


#3

If it is sterling as your friend said, then it will be sterling if
you just melt the castings she gave you. If it was me id ignore what
the so called “graduate” said, many so called graduates have too much
learning and not enough common sense/practical experience in this
trade. You dont say what the total weight of cast silver you have. If
it was me, id melt just say10 % and give it a try. you will know by
the feel of it, when rolling it down to sheet if its up to standard
or near enough to make no difference. also the colour will be a good
guide. Let us know how you get on.

go ahead and melt justa small


#4

Dianne- I believe that your teacher is mistaken. James Binnion may
have more detailed technical info for you. After all, he IS the
Metals Dude and I always bow to his superior knowledge.

I would add some fresh silver to the old castings.

Have fun and make lots of jewelry.
Jo Haemer
www.timothywgreen.com


#5

For practical purposes, she’s wrong. You melt down scrap sterling
silver, and you end up with metal that remains sterling silver.
You’re correct as well, that if you’re melting scrap that contains
solder or other non-sterling componants, then the result will also
not be quite sterling.

To be really picky, though, when you melt sterling silver in any but
the most controlled situations, some small percentage of the copper
will get oxidized. The result is that over many remeltings, the
percentage of copper slowly gets reduced, raising the silver content
slightly above the definition of sterling. You can still stamp this
metal sterling, as it’s better than sterling. And this effect is
small, needing many remeltings of the metal before it becomes
measurable by any means normally available to the jeweler. But it is
this slight reduction of the copper content over time that means
that technically, your instructor is possibly right. But in practice?
no.

However, one other aspect to consider is not whether it remains
sterling or not, but just the quality of the metal you end up with.
Remelting the sterling can introduce slight additional impurities,
mostly bits of copper oxide or the like, that can affect the final
quality of the sheet metal you’re making. If you’re melting
technique is good, this isn’t a big problem, but over time, scrap
metal can be harder to get consistent good sheet metal from…

Peter


#6

As long as the metal was sterling to begin with it will still be
sterling once you have melted it down and cast an ingot of it. As
long as you don’t add anything that is not of sterling or finer
quality to the melt no problem.

James Binnion
James Binnion Metal Arts


#7
I would add some fresh silver to the old castings. 

I throw in some fine silver (within reason) to re-melts. I make sure
my melts are pure and I get rid of the dross.

I’ve never had the problem of identifying silver, it’s never come
up, I usually buy sterling or fine silver. I’ve never melted old
silver, and never had to test it.

I’ve seen silver test kits, but they work in parts per million.

Regards Charles A.


#8

If it is sterling to begin with then the changes in composition
caused by melting is going to be very small. However, you may face
another problem when rolling your silver to make sheet or plate and
that is the alloy itself. All sterling will contain 92.5% silver but
the remaining alloying material can vary. Generally for sheet, wire
etc it will be copper but for casting it may contain silicon or
germanium as well as copper which gives super casting flow qualities
and a lovely finish when polished but hardens the alloy too much when
being rolled down and will most likely crack. Repeated annealing
doesnt really solve the problem. You can remelt the castings mixed
with scrap wire etc and that will reduce the problem and fluxing well
on melting will keep the alloy well mixed so you dont get hard spots.
Then you should hopefully have a workable sterling alloy. just dont
overwork it.

Nick Royall