Soldering Gold on Sterling Silver

I originally felt Jay may have been a bit hard on the Little
Torch, I had even bought, but not used one. I bantered a bit with
him about it, but no matter what others presented as to how well it
worked for them, he stood his point." 

Trying to use one torch for all the different types of jobs is like
trying to use a big or small hammer for everything. Sometimes you
need a large one and sometimes you need a small one.

I do fabrication, re-tipping, ring sizing, soldering gold bezels on
sterling, soldering heads on rings, and as much soldering of 14kt and
18kt white and yellow, and 22kt as anyone on this forum and I use a
Little Torch. I have for over 20 years, but I have other torches for
different purposes.

I use the little torch just about every day and just do not
understand the problem some are having with the Little Torch, unless
they are using the wrong torch for the task at hand…

95% of all my work is with the Little Torch, casting is with a very
large welding torch, and larger sterling work is done with a
prestolite acetylene torch.

“Standing on your point” does not make someone right, it is just an
opinion.

Richard Hart G.G.
Denver, Co.

Today Jay put out an appeal for a very flexible black hose that
was on a Mecco Torch when he first took over this studio. If anyone
has a clue as to what it is or where it can be bought, please let
Jay know. 

Kent White sell them at

… Also check out the amazing metal forming work Kent does. Warning
in big letters these hoses are for Acetylene only other fuel gasses
will attack them.

He also had read about using Airline Tubing, and has tried it. So
far so good, but he also asked if anyone else has any experience to
share about this tubing. 

There are some PVC tube formulations that will work well but the
standard stuff from a hardware store or pet supply is of an unknown
grade. Maybe ok maybe not. I would not suggest using the “airline”
or “Tygon” tubing without getting quite specific about which
formulation is acceptable for what gas. Running fuel gas or oxygen
through improper hoses is a recipe for disaster.

Jim

When you consider that 14kt gold has a higher melting point than
the sterling, 

Incorrect

Brepohl page 510

14kt yellow gold 802 C
Sterling Silver 920 C

http://www.meevis.com
http://hansmeevis.blogspot.com

I have found that it I hold the handle of my old PrestoLite torch as
if it were a pencil, I have much better control no matter how big or
small the tip is.

marilyn

14kt yellow gold 802 C
Sterling Silver 920 C

Well that was my first thought too but it is only part of the story.
First I would like to point out that there are a myriad of 14k
yellow formulations. I dont know which one Brephol was referring to
but that is a very low temperature for 14k yellow and I have to
believe 802 C is the solidus not the liquidus of the alloy yet, the
sterling temperature quoted is the liquidus. The liquidus is the
temperature or the point where there is no longer any solid material
in the alloy and solidus is the point where below that there is no
liquid present between them they define the melting range. Grimwade
lists standard sterling Ag925 Cu75 as 810C for Solidus and 910C for
the liquidus. It is not unusual to see discrepancies of 10 -15 C for
these points in the literature so 910C is close enough to 920C to not
quibble. Hoover and strong lists their 14k yellow (gold, silver
copper, zinc alloy) as having a 815C solidus and 843C liquidus. So
only 5C higher than the solidus for sterling but 14k yellow is quite
a bit lower when comparing liquidus values.

But regardless the typical 14k yellow solidus is damn close to
sterlings. Way closer than I would want to rely on for separation in
trying to solder.

The gold silver copper system has a minimum melting point of 767C so
when you combine silver and copper from the sterling and gold silver
copper from the 14k with a little molten solder alloy with a fair
amount of zinc in it then its not too difficult to heat things to
the point that you have a real mess on your hands without getting too
close to the theoretical solidus points.

The root of many beginners problems with this combo is too much heat
to try to overcome sloppy fit up and too long at temperature. A
perfect recipe for melting a bezel or other low mass part when
joining sterling to 14k Yellow.

Jim

James Binnion
James Binnion Metal Arts

Jim,

Thank you. I know this is exactly the answer Jay is looking for.

Speaking of using torches. When one works as a fabricating jeweler,
it is easy to set up the work area as you need it, different
torches, tools, etc. When setting up a teaching studio, it is not
easy to switch out torches and gases. Little Torch well may be
utilitarian for many of the projects on hand, changing torches and
fuels at a bench used by several, is not so. That is the reason for
looking for a torch with more utilitarian uses.

Hugs,
Terrie

Hans, as Jim points out today, thats a pretty lame statement (no
offense) because there are literally thousands of alloys of 14kt. I
like my alloys hot because I work hot.

And, as I said long ago, were not going to analyse the dogs saliva,
the dog likes bones.

Having gold parts just suddenly slump into a watery puddle when
soldering them onto sterling is a well known phenomenon. The why and
how is the curious part.

But regardless the typical 14k yellow solidus is damn close to
sterlings. Way closer than I would want to rely on for separation
in trying to solder. 

I imagine the solder would have an even lower melting temperature
than the 14kt gold.

I have fused thousands of sterling jewellery pieces with 14kt and
never have I had a problem with the sterling melting first.Check out
my web for many pictures of this technique.

And anyway, I was commenting on the statement that 14kt had a higher
melting temperature than sterling.

It does not. Basic stuff, really.

I have had some problems with this as well. I use a S mith little
torch on occasion, mostly for very fine work in sterling. My
workhorse torch is a jeweled Hoke that I have owned for 40 years
(propane / natural gas & oxy). I bought it for my apprenticeship, and
it still works just as good as it ever did. I have not run into a
torch that is substantially better.

Indirect heating of the work has helped. I appreciate the hints on
flushing the bezel with solder prior to attempting the join. I will
also bump the tip up a notch and try the more rapid heating.

Thanks for the tips.
Bill Carlie
Night Heron Studios
www.nightheronstudios.embarqspace.com

The first couple of times I had this problem was 14k yellow gold
bezel. Thats why I thought to use the 22k one this time, for the
higher melting point. Same problem though (just more expensive!). I
need a larger tip. I do have a rosebud tip for melting casting grain
that would deliver plenty of heat, though not as controlled…

I originally felt Jay may have been a bit hard on the Little
Torch, I had even bought, but not used one. I bantered a bit with
him about it, but no matter what others presented as to how well it
worked for them, he stood his point."

At the risk of redundancy, I too have a Smith Little Torch that I
use with Oxy/Propane. I also have an Smith acetylene air torch with
several tips - from a pin hole to about half an inch. I also have
Vigor, Hoke, National Blowpipe, Blazer, TurboTorch, a standard
welding /cutting torch and various propane bottle torches. I have
electrical joiners as well. A resistance welder, an ABI Tack I and
III, a PUK 111, several Sparkie welders and MIG, TIG and stick
welders.

If I had to choose only two, it would be the Smith Little Torch and
the Sparkie. The little torch can be a problem if you use propane,
not enough heat. The torch kit came with five tips, the #5 was the
biggest, not big enough for some larger silver pieces, so I bought a
#7 and it works great. You can also use MAPP gas or modify one of
the small tips, they even sell casting tips and double tips to heat
both sides at once. If you were serious, you could use hydrogen as a
fuel, which I understand works with the super fine tips with the ruby
orifice.

I listened to Jay’s audio cast, but gave up after listening to him
criticize the small torches for not being able to spit out a one
foot flame - If I had a one foot flame I would burn down half my
bench and melt the other half. I am sure he has reasons to like the
torches he uses, he reviewed several quality tools, but I find that
there are few jewelry jobs the Smith Little Torch cannot handle,
although I would not use it with large sculptural objects. The only
problem I have on occasion is with the high pin point temperature of
Oxy/propane. There are times when a larger lower temperature torch
like the Smith acetylene air will be easier to use.

Marlin

It looks to me like you are just creating the Ag- Cu- Au eutectic
that will be instantly liquid at 800C. I dont know what else you
could expect. If the base material is too hot once it starts it will
run to a full puddle now. You might be able to avoid this with very
great torch control. probably a place for a small tip and oxy -fuel
and great care.

jesse

Speaking of using torches. When one works as a fabricating
jeweler, it is easy to set up the work area as you need it,
different torches, tools, etc. When setting up a teaching studio,
it is not easy to switch out torches and gases. Little Torch well
may be utilitarian for many of the projects on hand, changing
torches and fuels at a bench used by several, is not so. That is
the reason for looking for a torch with more utilitarian uses. 

There are quick disconnect fittings made for use on Oxy/Fuel gas
torches they work just like the ones commonly found on compressed
air hoses. But they are designed to be safe for use with oxygen and
fuel gas.

They are like these
http://store.weldingdepot.com/cgi/weldingdepot/22-QC-RHPRSP.html

Your local welding supply will have them.

I have yet to find the torch that covers a full range of uses which
is why I have two at my soldering station.

James Binnion
James Binnion Metal Arts

If I had a one foot flame I would burn down half my bench and melt
the other half. 

So true. The problems with soldering most of the time is not that the
torch is too small, but because torch is too big.

Leonid Surpin

The first couple of times I had this problem was 14k yellow gold
bezel. Thats why I thought to use the 22k one this time, for the
higher melting point. Same problem though 

I’ll say a couple of more things on this long-lived thread.

I don’t carry the melting points of metals around in my head - I
consider that pretty pointless, for myself. I said that 14kt melts
higher than sterling because I thought it did (It “feels” like it).
So that’s news to me and I don’t mind saying it. It does take “more”
heat - that’s specific heat and likely the source of my
misunderstanding…

Much of this has been a defense from “I’ve never seen such a thing”
for me and also the other posters… I’ve never seen the Amazon
river, either…

And saying the best cure for the flu is to not get sick is equally
as useful.

But - I looked them up, just to know. 18kt is listed as being 35F
above sterling, 22kt is higher than that, and read the quote above.
Plus we’re only partially talking about melting points, because it’s
actually soldering temperature.

Which is only to say that it’s an interesting phenomenon (and
something to look out for), seemingly impossible or improbable, and
greatly illustrates the complexities of heat, specific heat,
conductivity, alloys and thermodyn amics in general. Things are not
always so simple…

Todd,

I use 14k gold solder frequently to solder gold to sterling
(argentium) with no problems. I prefer the look of the seam. I am
generally attaching bezels or wire details. I use 2 fluxes: boric
acid/alcohol and battens. The thing to keep in mind is the thickness
of the larger object, which is likely the silver, needs more heat to
make the solder flow compared to the extreme thinness of the bezel.
Heat from the back side of silver, do not hold the flame in one spot-
move it. Some solder blocks deflect heat and could be still be
heating the gold when you are unaware. Also, steel mesh and tweezers
are heat sinks that slow the heating process of larger items. I use a
smith little torch oxy/propane (unless I run out of oxygen or have
large job, and then I use a prestolite acetylene).

Melissa

1 Like

Melissa,

I think you are working on the right track for working with
argentium silver). You have the “touch”.

Argentium silver is different beast tan standard sterling. It either
adds a new problem or eases an old one.

It will always have a germanium oxide film when being heated in air.
The Germanium oxide melting point is quite high and will retard
diffusion and solution. This film will give problems in glass on
metal enameling and diffusion bonding of metals (in air).

Mark Grimwade’s original book “Introduction to Precious Metals” and
his new one only hint at the problems dealing with multi phase
materials.

The new one is about twice the content of the first book it is still
just an introduction.

Brepohl’s "Theory and Practice of Goldsmithing " is very much
more detailed, but will bobble most brains ( including mine).

The problem with soldering sterling silver to gold is at best a thee
component situation; involving sterling (silver- copper) and Gold (a
gold -copper and a filler metal(solder) that can be-gold- copper and
zinc. +more? A germanium oxide film on the sterling will complicate
making a bond, but may make soldering easier by retarding the
formation of the three component eutectic of gold -silver_
copper…Brepohl does a good job of showing this three component
phase diagram pages 40- 47, but fully understanding it can a" bit"
difficult.

Your procedure soldering with a small flame from the bottom of the
silver- copper " Sterling" fit mine.

The larger mass of the sterling and the less intense heat
application allow the eutectic to form slowly ( and stop if you pull
the torch back).

The heat fluxing is then immediately back to the sterling not from
it. Germanium oxide will retard this at best. and it probably is
really BEST.

Heating the sterling too fast will add too much heat there and the
eutectic formation and the gold puddle will form too fast to
prevent.

I am ready for the “flames”. I don’t comprehend more than two
component phase diagrams very well, and more than 3 will put me in
the bin.

jesse

So what’s the way to fix that issue you speak of

What do you mean dissolving? Wasn’t the question about the gold melting all over the silver, which in turn melts into the top layer of the over heated silver?,

Isn’t that sweat soldering?