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Sterling silver VERY Brittle?


#1

I am using slerling silver (20g) in my fused glass pieces for
earrings. I am fusing the wire into the pieces. After the pieces come
out of the kiln the silver is very brittle and breaks after one bend.
What is causing this? How do i fix it?

regards,
Andrea Streicher


#2

I can’t answer about the silver being brittle, but you need to watch
out for cracks in the glass. The sterling and glass probably have
different expansion ratios when heated and then subsequently cooled.
This difference will create cracks in the glass, probably invisible
to the eye, but can be seen under black light. These cracks greatly
weaken the glass. Carol


#3

We may need more info, but it sounds to me like you need to anneal
the wire prior to doing your other work. If the wire used is medium
temper and you fuse at a low temp you are likely keeping it at a
temperature that retains its crystal structure (ie organized and
brittle). What temperature are you firing your glass? How long is
the firing tempurature maintained? These asnwers are critical. You
may also let us know what you are doing with the parts that are being
bent. Annealed the wire will bend beautifully, but it will also not
have much strength or springiness.

Larry Seiger


#4

Andrea, It could be one of two problems or a little of both. The first
thing is that the time spent at the temperature required to fuse the
glass allows the crystal structure to grow very large this grain
growth means the metal will be very week and likely to crack due to
the larger inter-granular areas. The second issue is that the glass
contains metal oxides that make up the colors and the glass itself
can have lead oxide in it. These oxides can be alloying with the
silver at the he high temperatures and causing a brittle grain
structure…

I would look into using ni-chrome , kovar or even copper as the
wire and then forming that wire into a loop that you attach the
sterling earring wire to

Jim


@jbin
James Binnion Metal Arts
4701 San Leandro St #18
Oakland, CA 94601
510-533-5108


#5

This is a wild guess (being as how I’m not much up on metallurgy),
but it’s been my experience with some metals which I’ve "overheated"
for too long a period, that they become very brittle. I’ve had this
experience with both fine and sterling silver, and copper. I’ve also
wondered about what’s going on, metallurgically. I’ve always assumed
that at some point the metal just becomes fatigued. When you’re fusing
glass (assuming it’s the temperature of most fusible glass, like
Bullseye), you are soaking it at a fairly high temperature (I am
guessing 1500 to 1600 degrees) for awhile. You’re also cooling it
very slowly. Maybe fatigue is what’s happening.

I agree with the person who commented about the compatability issues
between silver and glass. You should definitely test your pieces
between two polarizing filter sheets to see if there’s stress. If it
doesn’t crack now, it doesn’t mean it won’t crack later. An
alternative method might be to fuse to nichrome wire (which is fairly
compatible), form it into a loop, and attach a sterling earwire to
that.

Rene Roberts


#6

Hey, you need to use pure silver, sterling silver just doesn’t hold
up. I use it when making glass beads.


#7

I believe your problem is that the heat used to fuse the glass is
hardening your silver. Normally, this is prevented by quenching the
silver before it is completely cooled. I believe quenching would
cause other problems with the glass. You may have to use another type
of metal. Michael / QuestFox


#8

Hello Rene; I’m new in this forum,but I have to admit … I love
it!! The answer to your qeustion is next.Your wild ques about
metallurgy is wright.What happens is next.As soon as you overheat
your silver (or gold item aswell),the copper start to oxidize turning
into copperoxide which is very hard and brittle.This is point number
one.Point number two is the next step of overheated silver.As you
know or don’t know,silver absorbes lots of oxygen in his fluid
state.This oxygen will go deeper down into your item combining itself
to the copper captured below the surface of your silver item
resulting into komma shaped copperoxide cristals known as
kommasilver.Again this is causing you a bigger problem since there is
now way of getting that copperoxide out of your alloy except melting
it down and using phospor copper as a deoxidant followed by pickling
it with a sulphuric acid solution. What do you need to do? 1.First of
all, avoid long soldering processes. 2.Wach your piece while you are
soldering and look for the color of your item which gives you an
indication of your temperature. 3.Use your flux and cover you piece
again as soon as you see that your flux is used up. 4.By all means,
I’m not the “one” to tell you how to solder,but review your soldering
procedure and try to find out what fact is exactly causing this
problem.It can be very simple but I found out by myself that routine
operation could become very nasty after a period of time.

I’m not awared about any reaction between glas and silver,but I do
know that “lead contamination” is causing exactly the same
problem,talking about silver becoming brittle. I do know that glas is
one of the items used for making a powder (which I use)for refinning
precious metal.The function of this powdered glas is capturing oxides
like borax,but will not evapurate.So,that fact make me believe that
glas does not interreact with silver.Again I’m not 100% sure about
this.

I have some more about this,but I do not want you to
overload with If you are interested,just let me know at
e-mail address:palonso.t-online .de By the way,sorry for the typing
errors.I do not control the English language that good.

See you,enjoy your hobby
With regards,Pedro.