I am trying to fuse together a ring formed of 20 gauge argentium
(4mm width). I have already fused a band of twisted 22k gold on to my
ring blank and am trying to complete the ring. Everytime I try to
fuse it the ring, which is fit together perfectly-it’s clean, the
edges meet perfectly thanks to use of a seperating disc, the set up
is correct-the ends move apart. At first I thought the metal was too
springy so I fully annealed it and then set up the seam again- no
luck. Then I thought I was overheating the entire ring so I use a
sharp flame tip just on the seam. Then I tried building up the heat
on the entire ring and then zapping the seam with a hot blue tip etc.
I have tried everything and every time the 2 sides pull apart. I have
even set it up in my third hand and put pressure on the 2 sides (like
using binding wire) and they still pull apart (I know argentium is
not supposed to have pressure on a seam but I figured I would try) I
have fused many many many 22k gold rings and also agentium rings-
this same thing also happened on a piece of argentium with a 18k gold
top surface- a bimetal. It has never happened with just gold or just
argentium so I think it must have something to do with the
combination of metals. Any suggestions??
It sounds to me like the problem has to do with the different
expansion rates of the two metals. It is perfectly okay to bind the
ring together before soldering. (That is completely different from
adding pressure when the Argentium Silver is red hot.) So, I suggest
that you bind the ring together with binding wire. If that does not
work, how about soldering with AS Hard? (You’ll probably need to
bind the ring for that, too.)
It has never happened with just gold or just argentium so I think
it must have something to do with the combination of metals. Any
suggestions??
I think you’ve answered your own question. It sounds to me like
you’ve created a bimetal strip. Different metals expand at different
rates when heated, which is probably why the ring edges are pulling
apart.
Can you possibly form and fuse the Argentium part, and the gold part
separately, and then fuse/solder them together after they are
individually closed? It may be more difficult to fit them together,
but it would more than likely solve the issue you’re having.
laura: i didn’t chck my metals handbook, but i suspect thet silver
has a greater coefficient of thermal expansion than gold. this would
cause the gold to expand less than the silver when you heat the
combination, particularly with the gold on the od of the ring, and
caust the gold to pull the silver joint apart.
i think the laws of physics are working against you.
A problem with fusing most metals is the thin oxide layer that
almost always occurs on a surface. Heating the metal only makes this
worse unless it is treated to remove or prevent it. A thin wash of
copper sulphate on the join may well do the trick as when the
sulphate is decomposed by the heat you get a thin layer of
copper/silver eutectic which lowers the melting point at that
contact. An alternative is to use a few sterling silver filings and a
touch of auflux, which contains borate flux and copper sulphate. The
MP of the sterling will be slightly lower than that of the argentium
but the solder formed will not tarnish or discolour or corrode as
much as silver-brass solder which is the normal silver solder.
Alternatively, get it laser welded. Costs about $20 commercially,
though some art colleges hve the kit and might be able to let you
have a “demo” for free.
Fusing temperature damages metal crystalline structure. Metal becomes
weak, high degree of polishing is not attainable, and many, many
other problems. What is wrong with soldering?
I now combine 18 k or 22k with argentium in all my work. The
differences in expansion of the metals is what is causing this. I set
the ring flat on a soft charcoal block and use T-pins stuck into
but I haven’t noticed any practical problems with fused being weak. I
only know about heat treating steel so I’d be interested in further
on how fusing temperature affects molecular structure
in .999Silver.
Sterling and solder introduces materials that are not.999Silver. as
soon as they are present you have to acknowledge and deal with them
on their terms.
by ironic mistake my first field of fused rings charred and
crumbled… like a burned marshmallow. Sterling.
Sterling and solder discolors under heat and requires pickle and
treatments. fine Silver remains fine. a quick rub with a Sunshine
type polishing cloth after fusing reveals a glowing Patina.
not better or worse, just different. I do one offs, so my take is
surely different than a production run thing.
Fusing temperature damages metal crystalline structure. Metal
becomes weak, high degree of polishing is not attainable, and many,
many other problems. What is wrong with soldering?
In metal work fusing (welding really) produces a stronger joint when
don properly than a soldered or brazed joint…
A fused joint is all the same metal a soldered or brazed joint, at
est could be described as an alloyed joint or if done poorly as a
glued joint.
Fusing temperature damages metal crystalline structure. Metal
becomes weak, high degree of polishing is not attainable, and
many, many other problems. What is wrong with soldering? In metal
work fusing (welding really) produces a stronger joint when don
properly than a soldered or brazed joint.. A fused joint is all the
same metal a soldered or brazed joint, at est could be described as
an alloyed joint or if done poorly as a glued joint.
While this can be true, it is not necessarily so. The heat affected
zone (HAZ) around the weld will often be weaker than the rest of the
bulk metal in the welded item due to the crystal growth from the
extreme heat of the fusing operation. The area that actually melted
will have even larger crystals than the HAZ. A well designed and
executed brazed joint can have very high tensile strength, if done
right the brazed joints tensile strength can exceed the tensile
strength of the bulk brazing alloy. My point is that the blanket
statements on this topic both need to be qualified by terms like
properly engineered and executed. Typical goldsmithing joinery is
neither of these. Both techniques are useful in the appropriate place
and arguing the superiority of one over the other without very
specific definitions of how a joint is designed and made are probably
a waste of time.
Learning to size by fusing has been a Godsend. I simply fuse in a
larger ball (broken lobster claw parts and misc.) and then grind off
the hazy part in shaping it. This is a major savings on very
expensive solder and sizing stock. It is so easier on those very
thin worn out antique rings that are a pain to solder a tiny piece of
sizing stock into. I have never had one break of come back. It is
great, and a major money saver!
Fusing has some uses for me. The problems are either cut out
afterwards, are on a small scale, or can be smoothed over.
Fusing a ring shank before forging creates a joint that will
withstand the forging process. The fused joint is cut out afterwards
to make space for the head. I find no solder that will withstand
heavy forging on a heavy ring shank. Yes, fusing an alloy will
produce cavities and porosity but the bond strength by fusing is the
strongest by far.
The lower the alloy the more you need solder, but solder cannot
withstand forging processes like a porous weld can.
I have a pulse-arc micro welder and it’s a compliment to the fusing.
The pulse-arc is not so good for a heavy fused joint, but it will
blow away all porosity on the surface and fuse a nice surface for
polishing. Yes there are cavities under the surface of a fused joint
but they are stronger than a soldered joint without cavities.
Fusing is easy with pure metals and gets harder with alloys. Try it
and find your own answers!
but I haven't noticed any practical problems with fused being
weak. I only know about heat treating steel so I'd be interested in
further on how fusing temperature affects molecular
structure in.999Silver.
In case of.999 silver fusing is an acceptable technique. In case of
alloy like sterling it is different matter. Problem is that copper
solubility in silver is less than amount of copper in alloy and
sterling contains silver crystal with a bit of copper dissolved and
copper crystals with a bit of silver dissolved.
When ingot is cast correctly, and forged, and rolled, and properly
annealed, and the cycle of working and annealing it repeats several
times - we get very refined crystalline structure. Jewellery made
from such alloy can be polished well, is strong, and can last for
many years. By bringing metal to fusing temperature, we are back to
the stage when we just cast an ingot, and maybe even worse.
I want to separate fusing from welding. Welding rarely affect the
whole piece, while fusing does. For metallurgical insight into the
process, check out the Web. There are tons of material on the
subject. There is also a book by Grimwade. Title is ‘something’
precious metals. I have not read it yet, but I heard good things
about it.
Now I am completely confused. How exactly does one “damage” metal by
heating it. We control the working properties of silver or gold with
heat and working… It is one of those things we learn from
experience… Guided by a firm understanding of basic theory.
Fusing changes that?? Really I am confused and not being
disrespectful. Metal is metal… I only have expe= rience with gold,
silver and iron… Heating silver or gold only anneals it for me:).
I know you can harden a metal in the kiln… But beating it with a
hammer gives me pleasure
The complexity of metalwork is there. I think most of us learn how
it “feels” to work a metal. For me, gold works very different than
silver… But you are comparing sterling with 14 or 18k. The working
properties are very different for me. I don’t really like to work
with 14k.
Having a “little” experience with metals makes one humble when
looking at what others have done. Look at some of the tesubas and
stuff japanese artists did a century ago… It should humble all of
us. Leonid is on the mark- but - I don’t think it is simple as you
are a goldsmith or a hack, but there sure as hell a difference
between what we can produce. It is the difference between devoting
your life to the art or playing. I am playing, but I sure appreciate
this weird group of experts and amateurs. Honestly, I have never
seen a group where the big players are so helpful and gentle with
this of us who are less talented.
I give to ganoksin via pay pal. Lurking is not free. If you are
reading this it is likely you are getting benefit from the experience
of others. Buy a book … Give on pay pal
Now I am completely confused. How exactly does one "damage" metal
by heating it. We control the working properties of silver or gold
with heat and working... It is one of those things we learn from
experience..... Guided by a firm understanding of basic theory.
Fusing changes that?? Really I am confused and not being
disrespectful. Metal is metal... I only have expe rience with
gold, silver and iron... Heating silver or gold only anneals it for
me:).
In very basic terms small equiaxed crystal structure is the most
desirable state of the crystal matrix when you are doing lots of
forming, or polishing. It is very rare for the metal to be in this
state after it is received from the mill. To get there you need to
put a lot of cold work into it (greater than 50% reduction in cross
section) then follow with the appropriate annealing temperature for
the correct amount of time. Unless one is doing serious hammer work,
drawing or rolling it is unlikely that one will get enough cold work
into the metal to get this small tight grain structure after
annealing, the more likely scenario is that you will get only a
reduction in strain on the crystal lattice with little change in
crystal size and the crystal shape will retain directional
characteristics from the processing it has undergone. However if you
heat too hot for too long you will get grain growth. The hotter you
heat the faster the grain growth can occur. Large grains make for
weak crystal structure and can create a structure that is prone to
fracture if severely formed or distorted. This is what Leonid is
alluding to. In raising or heavy forging it is absolutely necessary
to be aware of this as the deformation of the metal is so severe and
if the crystal structure is compromised you certainly will get
cracking. In most goldsmithing this is less likely to be an issue as
one rarely changes the cross section to that great a degree but it
is still something to be aware of especially if doing a lot of
bending and forming. One should try to limit the number of times one
anneals and keep the temperature and time as low as you can when
annealing. I can see his point about fusing in that you will be
creating large crystals and it will be unlikely you will be able to
put enough cold work back into that area to get the crystals back
down to a smaller tighter array. His point about polishing is true as
well, if you compare a tight, small grain polished metal surface and
that of a cast, finished and polished surface which will have about
as large a grain structure as you can normally create then yes the
small grain surface will be able to develop a higher degree of
polish. For a certain level of work this may be a relevant but there
is a tremendous amount of cast work that has a level of polish that
meets the need of the vast majority of makers and clients. This issue
in my opinion is one of trying for perfection. If perfection is your
goal then it is something to worry about but otherwise…
Fusing a ring shank before forging creates a joint that will
withstand the forging process. The fused joint is cut out
afterwards to make space for the head. I find no solder that will
withstand heavy forging on a heavy ring shank
Of course if joint can be forged it is a viable technique. I was
referring to situations like fusing bezel to foundation and etc.
Now I am completely confused. How exactly does one damage" metal by
heating it. We control the working properties of silver or gold
with heat
I am not sure, but when you fuse, you are getting the surface to
where it has a wet look, and I think that is taking the metal to a
point where oxygen can get absorbed into the surface and make the
metal somewhat more brittle.
When you solder, overheating the solder will create porosity in the
solder that results in pits when final polishing reveals these holes
in the soldered seam.
We control the working properties within the parameters of the
properties of the metal that does not create a crystal structure
that makes the metal unworkable for what you want to do with it.
Now I am completely confused. How exactly does one "damage" metal
by heating it. We control the working properties of silver or gold
with heat and working... It is one of those things we learn from
experience..... Guided by a firm understanding of basic theory.
Fusing changes that?? Really I am confused and not being
disrespectful. Metal is metal...
I have addressed what happens if metal heated too much, so let me
try to answer if metal is changed by heating, even if solidus point
is never crossed.
It is true that quality of crystalline structure of a substance
significantly affects it’s properties. A cliche example is diamond
and graphite. Same composition, different crystalline structure and
vastly different properties.
The same is true of metals, precious metals in particular. It is
goldsmith responsibility to create crystalline structure of the
finished piece. It starts with casting an ingot. Casting has
irregular, coarse crystalline structure. That is true irrespective
of the claims of casting community. Gravity cast ingots are worse
than those cast with centrifuges and vacuums pumps, but all of them
is pretty bad. That structure is improved by forging and subsequent
annealing cycles. Forging with cross-peen hammer breaks large
crystals into smaller fragments. Annealing re-crystallizes structure
into more uniform, smaller crystals entity. Repeating process
several times improves metal significantly.
Rolling ingot into sheet or wire is the next step. Changes to
crystalline structure is different. Rolling mill flattens the
structure. Crystals slide past each other forming different kind of
structure. It gives ‘grain effect’ to metal. When metal fully work
hardens, it must be annealed. Pay attention I said FULLY. If metal
under-worked, the annealing can be detrimental. How detrimental will
depends on the degree. Annealing after 90% work hardening is probably
fine, when annealing after 20% of work hardening should be avoided
at any cost.
This can be more difficult than it appears. Let’s say you finished
forming and in assembly phase. If there are several joints to solder
one after another, it could be trouble. First soldering acts like
annealing, but second soldering we annealing at 0% work hardening. So
you see, planning fabrication steps is crucial.
Even the best planning fails from time to time and we must ‘anneal’
at low percent work hardening. Then the character of flame and
heating pattern becomes important as well. Anybody who has my DVDs
knows that I use very deliberate pattern of heating. This is because
of one must damage the structure, at the very least the damage must
be uniform. The very important point to keep in mind is that there
are no ideal situation. Once one is in assembly phase, there will be
damage to metal crystalline structure. What separates expert from
beginner is the degree of damage that one inflicts. The better
original ingot is prepared, the more control goldsmith has over final
results.
This is very tiny introduction to a very complex subject. I want to
encourage reading authors like Brepohl, and try to plan fabrication
steps taking into account annealing and soldering milestones.
Fusing can be considered extreme form of soldering. Because metal
actually flows, the resulting structure is like after casting. If
forging is possible afterward, the damage can be repaired, but if
not than one has to consider carefully if it the best way to
accomplish things.
I’m not following the line of reasoning here that fusing pure Silver
or Gold “damages” them.
I will accept that sure changes occur when various heats are applied
to .999Silver, but why would that be considered as damage? the tone
of this seems to suggest that fusing temperatures are to be avoided
in favor of lower temperature soldering techniques, which in practice
will immediately render the precious metal in question no longer
fine.
I’m one of those crazy folks who consider the Spirit of a thing, and
to me, fusing is the most pure way of permanently bonding .999Silver
to itself without changing the nature of the .999Silver.
perhaps we are considering the actual sheer strength of the fused
metal as opposed to the strength of an annealed or soldered piece.
perhaps one must consider the wear characteristics of, say, a fused
clasp compared to one that has been soldered, like the difference
between softer spring steel and harder/more brittle knife hard steel.
seems to me that history has well proven both techniques as valid
for a given application and market. to say fusing is somehow inferior
to soldering when worn as Jewelry, or calling a fused piece
’damaged’, hmmm, I don’t think I’m understanding the thrust as
intended.
anyway, I would like to be further educated on the real world
practical ramifications of fusing verses soldering. for reasons solely
my own, I won’t be introducing solder into my .999Silver studio yet,
but I will incorporate strength considerations into my designs if I
discover a need or requirement beyond the properties of fusing.
