To quench or not to quench, that is the question

Helen,

A couple of things.

The “easy” way to tell that your silver has reached annealing temp
(and not above it) is to mark it with good old Sharpie marker prior
to heating. The sharpie mark will disappear completely when annealing
temp is reached. This is especially helpful when annealing a coil of
wire – just use a wide-tip sharpie and mark all around the coil on
the various strands… it will help ensure even annealing of all of
the wire.

Many folks - particularly students - tend to overheat their silver
when annealing.

On the topic of quenching, I ALWAYS quench into a pot of room
temperature water, and our studio’s rule for all students is to
quench only into water. Simple reason: Plain water, if splashed and
spritzed by the hot metal, does not cause problems when breathed or
gotten into your eyes. Pickle, on the other hand, can be quite
dangerous if it splatters or fumes up.

The temp differential between the pickle pot and the quench pot, in
the grand scheme of things, is not so great that it will make a
difference to your metal.

HTH!

Karen Goeller
No Limitations Designs
Hand-made, one-of-a-kind jewelry
www.nolimitations.com

regarding annealing, a book I have talks about taking the metal to
cherry red to anneal it, whereas another source said not to take it
that far but rather a sort of yellow/brown colour change. Which
would you recommend? 

There is a huge confusion about annealing temperatures. There is no
physically defined specific annealing temperature like there is a
melting temperature. Annealing is the re-growth of the crystals in
the metal or alloy.

When working metal the crystals are broken up into a smaller and
more stressed form as the metal is deformed by your hammer, rolling
mill, drawing dies,etc… As more work is put into the metal the
crystals get smaller and the lattice becomes more stressed,
eventually the lattice will contain more stress than it can handle
and fracture. A perfect example of this is the bending of a paperclip
back and forth till it breaks. A directional bias is also present
when the metal is stretched in one direction as in rolling or drawing
so the crystals take on a shape that follows the direction of
movement in the work.

So we need some way to remove the stress that has built up in the
lattice. By heating the crstals up to the point where they start to
grow again the stress is allowed to dissapate and the crystals
return to a normal equiaxed form. The question is “What temperature
is needed for this to occur?”. The answer unfortunately is “It
depends”.

Is it a pure metal or alloy?

Pure metals anneal at much lower temperatures than alloys. 

How much work has been put into it?

The greater the deformation of the crystal lattice before
annealing the lower temperature where it begins to anneal. 

How long are you heating it?

Annealing is a time/temperature phenomena the lower the
temperature the slower the re-growth. So you may be able to
anneal sterling at 900 F (482 C) but it would take hours. 

Finally how hot are you getting it?

The higher the temperature the larger the resulting crystals
are. There is still a time element so a high temperature for a
short time can result in the same sized crystals as a longer time
at a lower temperature but there will be less uniformity of the
resulting crystal sizes You can over anneal by overheating the
metal resulting in oversized crystals that create a weakened
crystal lattice and the dreaded orange peal surfaces that show up
when bending or polishing. 
And also how often should I anneal a piece? 

A rule of thumb is 30 % - 50 % reduction in cross section is a good
time to anneal. If you anneal too soon or too often you will not
achieve any stress reduction in the matrix because there will not be
enough in it to get the kind of re-growth and re-alignment you
desire. You also increase the size of the crystals and start to
degrade the integrity of the crystal matrix by over annealing. So
work the metal till it is too difficult to continue and then you are
probably close to the right time to anneal.

Regarding quenching. My book says to quench in water, whereas
people mention quenching in hot pickle. The hot pickle sounds
better than cold water. Is this the case? 

Never, never, never quench in pickle, it is dangerous (splashing hot
acid!) and it gets pickel into cracks and pinholes that you will not
be able to get it out of and will cause grief when doing further
soldering operations as it will contaminate the joint. Use room temp

After such fierce heat I have let it air cool rather than quenching
it. 

good idea

The thing I had most trouble with regarding cracking was a ring I
made from much thicker sterling (1mm thick). I suppose it is
probably a case of me not annealing it enough and therefore the
silver being too stressed. 

I seriously doubt this, it is more likely an uneven cooling rate or
just too hot when quenched caused he problem. Up to the point where
the metal actually breaks while working it the more stress the
better the anneal will be.

Jim

James Binnion
@James_Binnion
James Binnion Metal Arts

360-756-6550

" rodeo drive fancy designer alloys " will go by the wayside 

I think it will only get better. The properties of the argentium
alloys are just phenomenal. I have been making jewelry for 15 years
and 18 months ago I started using the sterling-germanium-copper
alloy exclusively and I have no problems. It has cut the labor on
solder preparation and clean-up by half or more and the color of the
metals is beautiful. I have never had cracking or breaking problems.
I have nothing but praise for the germanium alloy in my production of
my work.

I never did quench the silver-copper alloy of sterling at red heat
anyway. Not a good idea by my training.

Susan

Ok, I read this original post and decided to pass on it, partly
because they never said which metal they were using…As far
as sterling silver, though, I couldn’t tell you what books say, but
I’ve done it for 30 years. The writer talked about their silver
cracking after heating. That is quite simply because the metal was
overheated, and it makes no difference whether it was quenched or
not. Once you exceed a temperature, which is silver’s case is around
cherry red and up, the crystalline structure degrades and there’s no
way to restore it without refining it. The same thing happens when
you cast silver (or any metal) in a flask that’s too hot. The
crystalline structure is huge because it grows so slowly, and the
deed is done. The only way to fix it is to recast. As far as
annealing goes - annealing temperature for sterling silver is a dull
red heat, and hold it there for a bit. (Annealing is actually a
time/temp. curve). Once the metal has lost it’s redness, it makes no
difference whether you quench or not - the crystalline structure is
set in place. I think much of the confusion with this is because of
steel - someone mentioned tempering, which is a steel thing and has
no bearing on non ferrous metals. Heating steel involves the
interplay between iron and carbon crystals, and Martensite and stuff
like that, but that has nothing whatever to do with non ferrous
metals. If you heat sterling silver to a dull red heat, let it lose
the redness, and quench it either in water or pickle - or not, you
will have dead soft silver with no mishaps. I say this from having
done it 25,000 times, literally. Now, some people will want to
analyse the process, and try to squeeze another percentage point of
softness out, but I would wager that not a single person here could
tell the difference between 95% soft and 100% soft in any practical
way.

http://www.donivanandmaggiora.com

Nick,

So are you saying, anneal, quench, work, anneal, quench, work, etc? I
didn’t actually realise that quenching was part of the process! The
book I have mainly used and referred to doesn’t even mention
quenching. It goes on about the importance of annealing the metal to
keep it workable but doesn’t talk of quenching.

Helen

Hi Karen,

The "easy" way to tell that your silver has reached annealing
temp (and not above it) is to mark it with good old Sharpie marker 
prior to heating. The sharpie mark will disappear completely when 
annealing temp is reached. 

The Sharpie marker idea sounds a good one. I’ll try it. Yes I usually
use room temperature water too. I’ll let the red colour disappear
before quenching as this seems to be the opinion of everyone who has
replied.

Helen

Dear John,

It was me who posted this thread/question and I’m pretty sure I did
mention that I only use sterling silver at present. I have had lots
of useful replies and the repeated answer of letting the metal lost
the redness before quenching seems to be a big part of the answer to
my problems.

As for taking the temperature too high. I am confused about this as a
design I have made four or five times involved granulation where I
have had to take the temperature right up to the liquidus point of
the silver balls in order for them to fuse to the body of the piece.
I have done this successfully on all pieces made this way, with no
fracturing of the metal. The piece which did fracture was not taken
to such extreme temperatures. But letting any piece cool enough to
lose the red colour will probably solve that. Thinking about it, the
pieces with granulation, I let cool naturally and maybe they too
would have cracked if I’d quenched them too soon. I have also had
prongs crack in early pieces and those too were quenched too soon.
I’ll experiment and hopefully, with everyone’s advice and some more
experience, I start to get reliable, repeatable results.

Thanks for your advice.

Helen Hill

James,

Thanks so much for your reply to my questions. You have given me lots
to think about. That coupled with more experience and a feel for the
metal I am working will eventually make all become clearer.

Many thanks again.

Helen

Annealing occurs by the diffusion of atoms within a solid material,
so that the material progresses towards its equilibrium state. Heat
is needed to increase the rate of diffusion by providing the energy
needed to break and form new bonds. The movement of atoms has the
effect of redistributing and destroying the dislocations in metals
and (to a lesser extent) in ceramics. This alteration in
dislocations allows metals to deform more easily, so increases their
ductility.

That’s a quote that puts the concept better than I can. If you think
of a woven copper ground strap - that plated copper wire-strap that
some people make bracelets with, or sometimes it’s woven stainless
steel strap - it’s flexible and can even be bent into a circle of
some diameter. Think of the wires as the crystalline structure of a
metal, and think of the original out-of-the-box wire as being it’s
equilibrium state (it’s natural condition). Now take that strap and
flatten it with a hammer. What you will get is a stiff piece of
metal that is no longer flexible. What you have done is pounded the
crystals (wires) together - you’ve removed the vacant spaces between
them and crammed them tighter than they want to be. You’ve also
created dislocations - anomalies in the crystalline structure, as
when the wires in our strap cut into each other under the hammer
blows. The thing to understand is that this process is naturally
reversable - the metal will anneal itself over time (it’s true). That
is, it will relax all by itself, though it might take 500 years.
This is the time/temp. curve of annealing. The application of
energy, in this case heat, will accelerate the process, though, and
the structure will return to it’s equilibrium state. That is, the
crystals will “relax” the bonds that hold them so tightly compacted,
and move back to what could rightly be called a comfort zone - the
place where the bonds are just the right energy for the given atoms.
The reason why the metal doesn’t “puff up” in this process (though
it actually does to a tiny degree) is because the crystals have been
altered - what were once perhaps cubes have been flattened into
plates, and maybe stretched and elongated. But the atoms want to be
4 units apart, you pushed them together to be 1/2 unit apart when
you hammered on them, and annealing permits them to return to 4
units again. The most important thing to take away from this is that
you can never do more than the equilibrium state - the atoms want to
be (say) 4 units apart, and nothing you do will make them be 6 units
apart - more heat or more time is NOT better. And once the heat and
the return to that state is finished, it makes no difference what
you do (quenching) - the thing is done. What can and will happen
with more heat is that you will destroy the crystalline state and
create dislocations. The more you approach a liquid state, or
melting, the more the crystals will fall apart, and the only way to
restore them is by remelting. Crystals are a geometrical unit, and
if you heat one and one corner falls off, metaphorically, when you
remove the heat the corner isn’t going to return in place, you’ll
have a broken crystal, and you’ll get cleavages and cracking in that
place.

http://www.donivanandmaggiora.com

Helen,

I have had to take the temperature right up to the liquidus point of
the silver balls in order for them to fuse to the body of the piece.

Several times in the past I has soldered sterling casting grain to
the background of a design. I soldered the grain to the background by
first heating the piece and coated the background where the grain was
to be placed with solder. The grain is then placed on the solder as
the piece is heated again. When the solder flows the grain is
soldered in place.

Lee Epperson.

To quench or not to quench, that is the question.

I have resisted commenting on this subject because, being self
taught, I have no technical background to add to the subject.

The subject reminds me of my Karate instructor. When ever he taught
us a new technique we would asked him the name of it. His answer was
always, “No name, just use.”

That’s sort of the way I solder and quench. No reason just use.

I use medium solder. Most of my jewelry is cast and heavy. I use 18
gauge bezels.

I coat everything with Cupronil. I set my project so that it rests
between two fire bricks so that I can heat it from the bottom. I
mark the top with a Sharpe felt tip pen. When the black mark starts
to disappear I take the flame to the top and wire solder the
fittings. Why? No reason just use. I think I solder from the rear
because 30 years ago when I started soldering I melted a bezel when
playing the heat on it from the top. That’s probably why I use such
heavy bezels.

Now to quenching. I immediately spray the project with Cupronil
after turning off the torch. Why? No reason just use. I think 30
years ago I picked up a piece right after tuning off the torch.
Something moved as the solder was still liquid. To solve that I spray
the item to set the solder. After spraying the item I drop it in a
plastic container which is about 10 inches tall with a 4 inch opening
that is half filled with Cupronil. Why half filled. No splash. Why
Cupronil. No reason just use. Many years ago someone wrote me saying
they thought their item came out a lot cleaner when quenched in
Cupronil. I don’t recommend that. I have an unlimited supply of
Cupronil as I manufacture it.

The proper hand to hold your torch?

I am right handed. The top part and bottom part of one of my big
pieces of pottery, which I solder together, weigh about 20 ounces
each. I mount an acetylene torch in a heavy portable vice so that the
flame plays on the assembly. I hold another torch in my left hand and
play it on the assembly. I hold wire solder in my right hand and wire
solder the two pieces together when the temperature is right.

Lee Epperson

Hello Lee,

That sounds like a much better idea than attempting to fuse weld,
especially as I am only a beginner. In fact I have used solder if any
of the little beggers have fallen off when pickling. I’ll try that
next time.

Helen

A traditional method is to coat the contact area in copper sulphate
and gum taraganth solution which changes the eutectic at the surface
and fuses that bit before the rest has a chance to melt.

Nick

What happens to the gold in my current work, after annealing it over
and over, probably more then 100 times!.?

I’m working on this miniature Chasing project that has been going on
for months. The piece is in 19k peach gold.

very delicate and detailed deep relief work. I’m weary not to push
the metal too much on each chasing cycle.

The nature of the work is such, that only small areas reach’s work
hardening before annealing! Certain areas doesn’t get worked at all!

I anneal carefully in deem light till the gold reach dark red, let
it cool a bit to black heat and quench in alcohol.

So far the metal seems ok after repeated burnishing. I pickled only
a handful of time, mostly I just clean the boric-acid residue in the
ultrasonic.

Do I stand the risk of nasty eventual surprises from a deteriorated
alloy?

Are there any steps I can do now? Improving the gold’s lattice
structure?

One more question on a different issue on the same piece: In order
to achieve dark [antique] background I consider heating without the
boric-acid. The highly burnished gold comes out very nice in
bluefish-purplish black on this alloy. But how to protect the areas
which are to remain un-scaled and gold looking? Details can be less
then a millimeter, so I’m looking for a very precise technique?

Painting in some acid resist and pickling is not preferable. I’d
like to keep the peach shade of the gold?

Thanks to Orchid
Love and Light
http://www.akashjewels.com

over and over, probably more then 100 times!.? 

Akash, you can anneal as often as you need to, it will do no harm.
That’s the easy answer - silversmiths - the kind who make pitchers
and punchbowls - will anneal more than 100 times on pieces. Even
1000 times. Here’s what happens to metals with heating - this means
silver, and copper, and by extension brass and bronze. Steel and
exotics are entirely different. Metal is a crystalline structure,
even if it doesn’t look like it. If you get a lump of silver and
heat it, it gets hotter and hotter and the atoms that make up the
crystals get more and more excited and start to break the bonds that
hold them together in a crystalline lattice, becoming free atoms
(again). Eventually all the crystals disintigrate and the metal
melts. Then what you have is a mass of atoms - no crystals. Remove
the heat and the atoms find each other and arrange themselves into a
neat geometrical pattern - a crystalline lattice - and the metal
freezes again. There is a space between the atoms in that structure
which is a distance dependant on what the atoms are - what your
alloy or metal is. When you pound on the metal, you are pounding the
crystals closer together, and lessening that space. It is that space
that gives metal its maximum softness and flexibility. You are NOT
altering the crystal itself in the sense of breaking the bonds. If
you get a cardboard box, remove the ends, and push on the square of
it until it becomes diamond shaped and then ultimately flat, that’s
what you are doing when you pound it. No force that you can apply
will break the bond between the atoms in a crystal, though you can
cleave them - turn big crystals into several small crystals. When
you anneal the metal, you are applying just enough energy to allow
the atoms to return to the position of having the space they want to
have. As long as you do it carefully, you can do it endlessly. The
bad thing is when you apply too much heat. Then the atoms get too
energetic and the crystalline lattice starts to break down. If the
crystals disintigrate there is some chance, I suppose, that they
will reorient themselves when they cool, but mostly they won’t. The
only real way to grow crystals is by growth from a liquid state. If
you think of that as a perfect crystal, which it never really is,
and then you heat to an excessive degree and cool, you may get some
crystals back, but they certainly won’t be perfect anymore. That is
precisely why heat control is so important, because of what it does
to the atoms in the crystalline lattice. But as long as you don’t
heat to the point where the atoms free themselves, which approaches
melting point, then you’ll be fine.

Akash, you can anneal as often as you need to, it will do no harm. 

Blundells a small bullion dealers in London England used to have a
sign up about annealing and subsequent cracking of silver.

Basically if you keep annealing without protecting the silver from
firestain the copper oxides that form, go deeper and deeper into the
metal. When you work the metal, hammering or bending the oxides are
brittle and will form micro cracking which subsequently propogates
cracks into the body of the metal.

A good coating of Prips flux or Argotect will prevent this, and also
mean that you wont have to get off the firestain.

A few annealing wont matter, but if you are raising and are doing it
a lot, it will. You wont realise though until you have put in most of
the work, and time.

regards Tim.

Hi John,

There is a space between the atoms in that structure which is a
distance dependant on what the atoms are - what your alloy or metal
is. When you pound on the metal, you are pounding the crystals
closer together, and lessening that space. It is that space that
gives metal its maximum softness and flexibility. You are NOT
altering the crystal itself in the sense of breaking the bonds. 

While there are some voids in a metal as cast (porosity) but by the
time you get it as sheet it is well over 99.9% dense. At that point
you can not change the density of the material by any means that we
have at hand in a studio. You cannot change the spacing between the
atoms in the lattice by hammering on it. If you did you would in
effect be able to change the density of the material by compression
which you cannot do. You do not change the volume of the material
you change the crystals shape and size as you add strain to the
matrix and larger crystals fracture to become smaller ones. The
orientation of the crystals change with the direction of the applied
strain.

No force that you can apply will break the bond between the atoms
in a crystal, though you can cleave them - turn big crystals into
several small crystals. 

Actually it is not all that difficult, just work the metal to the
point where it breaks. Some of the fractures are along the grain
boundaries but some will be right through the middle of the crystals
breaking the atomic bonds.

Hope all is well in SF

Jim

James Binnion
@James_Binnion
James Binnion Metal Arts

360-756-6550

A few annealing wont matter, but if you are raising and are doing
it a lot, it will. 

My introduction to metal work was repousse. To do it well, one has
get very familiar with annealing.

I worked with pure copper, so the “fire stain” effect is not a
problem, but if annealing is done incorrectly the work will crack.

The problem with annealing is that very few artists are actually
trained by people who actually know what they are talking about, and
almost all the books on the subject are useless.

The best book instruction, I have ever seen, is to anneal at cherry
red, which is technically correct. What is never mentioned is that
cherry-red must be observed in the dark. If one anneals at normal
shop condition, it would result in over-heating, and over-heating is
deadly.

Another problem is work must be stressed evenly, which means that
every area to be annealed must be worked the same or close to it.

In repousse the trick is use your ears. There is a particular ringing
when work is ready to be annealed, which can only be learned by
experience.

And I know that nowadays artists wear ear muffs or head phones while
working, which is an abomination in my opinion.

It is a bit trickier in jewellery because hammering just to equalize
stresses is not an option. A careful planning is needed.

How many times one can anneal ? Thousands upon thousands if metal is
not over-heated and work stresses are distributed evenly.

I can anticipate responses that hearing must be protected while
hammering. I am not going to give anybody medical advice. I have been
doing it for many years, not as much now as before, and my hearing is
fine. The damage to hearing occurs if ringing sound is dominated by
odd harmonics, which only happens if hammering is carried out beyond
the annealing point.

Leonid Surpin.

Hi Tim,

Thank you for your explanation. It seems one of the most logical
explanations to my problem. I think an order for Prips is in order!
Would I use Prips in place of borax/water or as well as? Probably a
stupid question as it does the same job, so in place of would be
logical.

Thanks again.
Helen

Dear John and Jim,

I started this thread and I have had some very interesting
responses.

While there are some voids in a metal as cast (porosity) but by
the time you get it as sheet it is well over 99.9% dense. At that
point you can not change the density of the material by any means
that we have at hand in a studio. You cannot change the spacing
between the atoms in the lattice by hammering on it. If you did you
would in effect be able to change the density of the material by
compression which you cannot do. You do not change the volume of
the material you change the crystals shape and size as you add
strain to the matrix and larger crystals fracture to become smaller
ones. The orientation of the crystals change with the direction of
the applied strain. 

Jim, yes you are correct (as is usually the case given your vast
knowledge of metallurgy which is clearly evident). Implying one can
compress a metal by making the spaces smaller is like saying that
you can lessen the distance between the electrons and the nuclei of
an element - impossible. Although metallic bonding is a little
different to other solids in that the atoms are ionized, with the
positive ions (nuclei and inner electrons) occupying lattice
positions and these are surrounded by a freely moving “sea” of
valence electrons, accounting for the electrical conductivity of
metals and alloys of metals. But it can still not be compressed
smaller than the lattice arrangement of the atoms involved.

You must have had a very interesting education Jim. Do you have a
degree or higher in metallurgy? My chemistry degree is long forgotten
as I’ve not used it for years and as such I have found your posts
very interesting.

Helen