Alloying bronze for casting

So I stand by my statement that there is virtually no loss of tin
by evaporation at the melting temperature of the bronze. 

We have historical evidence to confirm this statement.

Russians are renown for having casted really large bells. The
technique was to prepare mold, which was buried in the ground, but the
top was completely open. Bronze was melted in multiple pots located
around the mold perimeter, and all these pots were emptied into mold
simultaneously.

Any caster would see the problem with this method, so to overcome the
problem of premature cooling, bronze was brought to much higher
temperatures than would be necessary with conventional pour.

Russians used 78% copper and 22% tin, an alloy with greater potential
for evaporation, if it would be a factor. We know that bronze was
remelted many times, because not every casting attempts was
successful, so bronze was reused. All historical bell actually
indicate how many attempts it took to cast it. Famous Tzar Bell is
actually known as Tzar Bell III.

Peter the Great, in preparation to war with Sweden ( Great Northern
War ) ordered to remelt all bronze bells into gun barrels, and these
guns performed beautifully, as evidenced by historical accounts. And
what could be a better test to the soundness of an alloy as using it
for gun barrel.

Leonid Surpin

Silver and copper, and gold and copper, however, both have eutectic
points. 

While the liquidus and solidus do come to a minimum this alone does
not indicate a eutectic. The structure of the Au-Cu phase diagram
does not form the eutectic “V” and the crystal structure of the alloy
does not form the eutectic crystal structure. In a eutectic forming
system you have two distinct crystal structures in the solid state
the alpha the beta also there is an invariant range in the diagram
where the solidus is held at a single temperature. In the silver
copper system you can see this very clearly where the eutectic
defines the solidus temperature for the alloy range between 8.8% -
92% copper at 1435F you do not see this invariant area in the copper
gold system.

James Binnion
James Binnion Metal Arts

Or just don't use alloys with lead in them. ;-) CIA 

While if you alloy your own this is possible but if you are buying
your material you will find this is very hard to do as lead is
present in a large majority of copper alloys.

James Binnion
James Binnion Metal Arts

Hi Leonid et al,

I’m wondering if they built in evaporation rates into the bells. If
the tin evaporated off you would end up with a higher percentage of
copper in the resultant alloy.

Bell metal which these days is roughly 80/20 is very close to your
example of 78/22. If you’ve ever played with it, it’s extremely
brittle. In a thick walled bell that’s not really an issue, however
in a gun barrel it would be horrendous. So I don’t believe those gun
barrels would been a straight bell metal, the alloy is simply too
fragile.

Just confirmed it. Peter did not cast guns from Chruch bells, but
did cast cannon balls, which which makes more sense. Pretty much
anything can be used as cannon shot… even cheese has been used as
effective cannon shot.

Interestingly Kolokol III (Tsar Bell) was never in use due to
defects and is a testament to poor casting practices. It’s still a
pretty nice sculpture though. Kolokol IV was never attempted after
the third failure.

Regards Charles A.

While if you alloy your own this is possible but if you are buying
your material you will find this is very hard to do as lead is
present in a large majority of copper alloys. 

James, one of the reasons I alloy my own is that I control what goes
into the melt, and what goes into my lungs.

Regards Charles A.

Just confirmed it. Peter did not cast guns from Chruch bells, but
did cast cannon balls, which which makes more sense. Pretty much
anything can be used as cannon shot... even cheese has been used
as effective cannon shot. 

The way Russian history is taught, Peter did use it for barrels, so
I am curios what is your sources?

Interestingly Kolokol III (Tsar Bell) was never in use due to
defects and is a testament to poor casting practices. It's still a
pretty nice sculpture though. Kolokol IV was never attempted after
the third failure. 

The problem with Tsar Bell is that casters in order to lower
temperature even more, used lead as a part of the alloy. Presence of
lead does render bronze brittle. Pure 78/22 copper tin is not
brittle, but impurities needed watching.

When Tzar Bell was cast and left in the pit to cool off, the church
caught fire at night and some burning timber fell on it. To prevent
bell from melting all over again, they used water to extinguish the
fire and rapid cooling cracked the bell.

Leonid Surpin

James, one of the reasons I alloy my own is that I control what
goes into the melt, and what goes into my lungs. 

I understood that, I was posting for the benefit of others.

Regards,

James Binnion
James Binnion Metal Arts

Hi Guys,

The way Russian history is taught, Peter did use it for barrels,
so I am curios what is your sources? 

Well, I’m not inflexible, and if you say that that’s the way Russian
history is taught, I have no reason to doubt you, I’m not Russian. I
looked on the internet, and found quite a few references to balls
being cast as opposed to cannons being cast.

So I can concede the point.

However, there’s no way you’d make a cannon out of straight bell
metal, you’d need to add something to change the alloy sufficiently
enough so that it wouldn’t shatter.

I suspect they added more copper to the melt to make bronze cannons,
as opposed to bell metal cannons.

When Tzar Bell was cast and left in the pit to cool off, the
church caught fire at night and some burning timber fell on it. To
prevent bell from melting all over again, they used water to
extinguish the fire and rapid cooling cracked the bell. 

Well if you can make bell metal that’s not brittle, my hat goes off
to you.

However bell metal is supposed to be brittle. Bell metal is a 2
phase alloy. It is harder and more brittle than a single phase alloy
such as ancient bronze.

Why would you make a metal that can be shattered under a hammer
blow? For it’s tonal qualities. If you hit a bell that is made out of
bell metal, it wont crack, because the bell is allowed to move and
ring freely. If a bell, made out of bell metal, is not allowed to
move freely, when struck, it will crack.

Try it, cast an object out of bell metal, and drop it on a concrete
floor. I use pure tin and fine copper 80/20 (which is still bell
metal), and contains less tin that 78/22.

The first shatter for me, was when I had been casting pure bronzes
for a while. At this stage my castings were without porosity or
defects, so I decided to try a bell metal for its colour, which is
very pale, and only slightly bronze. I had made my ring, and was
cutting it from the sprue, when it slipped out of my hands, and fell
to the concrete floor.

Not only did it make a lovely sound, it shattered. I had failed at
making a ring, but I had succeeded at making a pure bell metal.

The picture you paint of the casters is poor. Not only did they add
lead to their melt, which would have been okay if they weren’t
making bell metal, as it would have made the alloy more ductile and
screwed up the tonal qualities of the alloy.

They poured water on a casting, that hadn’t solidified 100%, to
prevent the bell from melting again, and assured their failure,
because the bell wasn’t ever used or cast into a functioning bell.

Regards Charles A.

Charles,

James, one of the reasons I alloy my own is that I control what
goes into the melt, and what goes into my lungs. 

There are trace amounts of lead in most copper alloys. Another
concern is that the stuff is everywhere. 70 odd years of putting it
in gasoline. Then it got blown out the exhaust pipe and didn’t just
go away. Don’t scuff your feet walking on the side of the road :slight_smile:

jeffD
Demand Designs
Analog/Digital Modelling & Goldsmithing
http://www.gmavt.net/~jdemand

(Tsar Bell) was never in use due to defects and is a testament to
poor casting practices. It's still a pretty nice sculpture though. 

One of those poor casting practices was that local people would
throw in silverware and all sorts of things - both to provide metal
and to have a piece of the family in a bell made for posterity. When
I was researching bell making, that was ~the~ reason they gave for
it’s failure. Probably not just that - it was a monumental casting in
relatively olden times…

People have been casting huge things for ages, Europe is no
exception.

I just think this example was just a series of bad decisions.

I still would like to touch the Tsars bell though.

Regards Charles A.

There are trace amounts of lead in most copper alloys. Another
concern is that the stuff is everywhere. 70 odd years of putting
it in gasoline. Then it got blown out the exhaust pipe and didn't
just go away. Don't scuff your feet walking on the side of the road

Another reason why I alloy my own metal, no lead in my stuff. More
of a problem for me is sulphur (sorry I’m old school, and that’s the
way I spell it :wink: ), as I have an allergy to the stuff (more an
intolerance really), now sulphur is everywhere. Took me ages to fine
a sulphate free toothpaste.

I have friends that wont fly because aeroplanes are made from
aluminium, and the tarmac is marked out with mercuric salts.

You can guard against most things, and the more control you have the
better it is imo.

Regards Charles A.

They poured water on a casting, that hadn't solidified 100%, to
prevent the bell from melting again, and assured their failure,
because the bell wasn't ever used or cast into a functioning bell. 

I am not ready to pass judgement on bell casters of that time. I have
tremendous respect of what they been able to achieve with primitive
equipment.

Two points I would like to make. First is the bell metal is not
brittle if properly smelted. Properly smelted is not just a phrase.
If composition of tin exceeds 25% alloy will be brittle. Just by
melting 78 grams of copper and 22 grams of tin does not necessarily
makes 100 grams of 78/22 alloy. It is often the case that some parts
of alloy contain more than 25% of the tin and there is the problem.

The second point is that bell casting was always shrouded in
mystery. The precise composition that each master used often included
various additives, which are not documented. Materials like copper
and tin were not refined to todays standards and contained
impurities. Some of them were helpful and others were harmful. Each
master used empirical knowledge to deal with it, and a lot of
practices were quite weird at first sight, but from view of modern
science actually make a lot of sense.

The main point is that we should never assume that just because we
following some recipe from some old book, we doing exactly the same
thing.

Leonid Surpin

I am not ready to pass judgement on bell casters of that time. I
have tremendous respect of what they been able to achieve with
primitive equipment. 

Well I think you can, if you judge by what other founders were doing
in Europe at that time, and what had been achieved earlier in many
cultures around the globe.

As far as founders go, with respect to the Tsars Bell, the 18th
century isn’t that primitive.

Other masterpieces were achieved around the same time, and in the
same country.

I just think they screwed up, and the guys commissioning the piece
decided to cut their losses. I wonder what happened to the founders,
I wonder if they were punished? (Just curious).

Two points I would like to make. First is the bell metal is not
brittle if properly smelted. Properly smelted is not just a
phrase. If composition of tin exceeds 25% alloy will be brittle.
Just by melting 78 grams of copper and 22 grams of tin does not
necessarily makes 100 grams of 78/22 alloy. It is often the case
that some parts of alloy contain more than 25% of the tin and there
is the problem. 

Where did you get the idea that bell metal isn’t brittle? Pure bell
metal with a percentage of tin over 15.8% stops being a single phase
alloy.

I suppose we could go around forever saying “yes it is!” and “no it
isn’t”, so I’ll back up what I say.

Apart from personal experience at making a pure bell metal, and
concluding that “yes, it does have good harmonics”, and “yes, it’s
brittle”, which can be discounted as anecdotal.

There’s this :-

http://www.ganoksin.com/gnkurl/3i
http://www.ganoksin.com/gnkurl/3j

To add to this I’ve sent off an email to a bell foundry, asking them
to confirm or refute what I have said. If they reply I will share the
correspondence.

The second point is that bell casting was always shrouded in
mystery. The precise composition that each master used often
included various additives, which are not documented. Materials
like copper and tin were not refined to todays standards and
contained impurities. Some of them were helpful and others were
harmful. Each master used empirical knowledge to deal with it, and
a lot of practices were quite weird at first sight, but from view
of modern science actually make a lot of sense. 

Well that’s true, true were in the same occupation as alchemists,
and kept a lot of secrets almost like a secret religion.

Used to have an excellent video about casting aquamanillia, that
illustrated this point, which unfortunately I can’t locate online
anymore (I did take a copy of the video for future reference, it’s
182 mb, it will fit on a CD, but be a tad hideous to upload). It’s a
really good documentary, I think you’d appreciate it Leonid, send me
your address.

However they were documented, but in a code that other alchemists,
and founders could understand.

The main point is that we should never assume that just because we
following some recipe from some old book, we doing exactly the
same thing. 

I agree, that why you should experiment when you can :slight_smile:
Regards Charles A.

I have never seldom used bronze for jewelry but have cast most any
alloy you can name with success (with the exception of "railroad"
bronze with high aluminum content). For reasons of safety and the
quality castings it produces for me, I only use silica bronze in the
foundry these days. Would silica bronze be a good choice for jewelry.
It certainly does not shatter and seems durable enough. I have used
it to cast tiny sculptural objects centrifugally and they turned out
fine.

GLV

To add to this I've sent off an email to a bell foundry, asking
them to confirm or refute what I have said. If they reply I will
share the correspondence. 

Your whole argument is a total nonsense. Before you continue do
yourself a favor and study about bell casting. Tsar Bell is one
thing, but there are many others very large bell, which are still
functioning. Let me give you some examples - Everyday Bell - 36000
pounds, Reyute Bell - over 70000 pounds, Dormition Bell - almost
150000 pounds, and many others still ringing. These are not the
largest by any measure.

Are you really want to continue to argue that bell metal is brittle
when none of these bells have cracks, after 400 years of use ? Do you
have any idea of thermal expansion from winter to summer that these
bells undergo twice a year? Do you understand physics of sound ? What
kind of vibrations a bell has to endure to ring?

Your argument is a great example of how dangerous the little
knowledge is. When bell metal is composed the correctness of alloy is
determined by it’s fracture. Yes. alloy is intentionally fractured
to study the appearance of fracture. I suspect that the practice of
fracturing sample gave rise to this falsehood. You also apparently
unaware that there is a post-casting treatment of bell metal which
renders is very tough so it can endure expansions and contractions. I
am not going to get into details of the treatment.

Do you realize that you are arguing against several hundred years of
experience, which contradicts your statements?

Leonid Surpin

I find all this really interesting and it got me to thinking about
all the references to SILVER bells, as in: Silver bells! Silver
bells !It’s Christmas time in the City. Ring a-ling, Hear them ring,
(Etc.) I don’t think I recall ever actually seeing a silver bell.
I’ve seen some silver COLORED hand bells, but none I’ve known were
actually silver (maybe bronze with silver plate?). So are bright,
little tinkling bells ever made out of silver or one of its alloys?
If so, it might be fun to play around with all theextra silver I have
laying around (uh, yeah, right!).

Denny Turner

Hi Guys,

Detailing personal experience, and providing links to information
supporting what I was saying obviously wasn’t enough.

I asked people that deal with large quantities of bell metal, and
have more experience than either Leonid or I.

This is the last I will say on the matter of bell metal, because I’m
sure you’re sick of the discussion, but I suspect that even the
knowledge of experts wont be enough.

Regards Charles A.

…

Dear Sir Thank you for your email of 4th February. We can confirm that
bell metal is brittle.

Yours faithfully
[name removed]
Whitechapel Bell Foundry Limited
whitechapelbellfoundry.co.uk

So are bright, little tinkling bells ever made out of silver or one
of its alloys? If so, it might be fun to play around with all the
extra silver I have laying around 

Sure thing.

Jewelry Lesson - Making a Bell

Cheers, Hans

I've seen some silver COLORED hand bells, but none I've known were
actually silver (maybe bronze with silver plate?). 

Dennis, this: http://www.ganoksin.com/gnkurl/4a

Is one of the two “real” bells I have made, and it’s sterling silver

  • the “next” button has another view of it. It’s modeled on the
    Liberty Bell and it’s about 3" tall. BTW, a simple search for “bell
    metal” will take you to Wikipedia, and onwards to “bellfounding”,
    which addresses pretty much all the things ~argued~ about here. I
    suspect that the “silver bells” of song are nickel silver, and most
    of those are “jingle bells”, otherwise known as sleigh bells. Those
    are sheet metal, not true bells and they sound by being clashed
    against each other.

Quickly… True bells are cast and tune-able. They have varying
thickness throughout the bell, which determines the tune (note),
gives them overtones or harmonics, and makes them project sound.
They can be made out of anything, but bell metal is the best for the
best tone, which is why it’s used. My silver bell sounds good - it’s
not tuned, really. But it’s sound is weaker and a little “tinnier”
than the brass bell I made before it.

Bell metal is about the hardest bronze there is, which gives it good
resonance. Drop a brass disk (or a quarter) on the floor and hear it
ring. Drop a pewter disk and hear it go “thud”. And yes it’s brittle
in the sense that if you hit it with a sledge hammer it will break
rather than bend.

Try bellfounding on Wikipedia for a start - it’s a whole, unique
process that’s quite interesting…