Back to Ganoksin | FAQ | Contact

Bronze from copper pipes


#1

Greetings Craftspeople:

I have some copper plumbing pipes with the solder scraped off. Can
use this to make bronze for jewelry?

Is the copper safe enough? I would think so because it was used for
drinkable water. Where can I find safe tin? How would I add silicone
for silicone bronze?

Please send Thank you.


#2

Hi Sally,

Copper is copper, if you melt it in a furnace, you can skim off
impurities. Make sure there is “no” solder on those pipes. If the
pipes are old it may well be a lead based solder. Lead will add
ductility to your bronze, but it will also make is a slightly
different colour.

There is copper cookware, although I don’t like the taste that it
imparts into the food. The plumbing in my house is high grade
copper, but even that is being eroded. In some outlets I cannot drink
the water as I have sensitivities. In the newer parts of the house
this is not a problem.

Buy your tin from a metal merchant.

Why add silicon? A safe bronze is 90/10 (90% copper, 10% tin), and
if you alloy is correctly it will make beautiful jewellery.

Regards Charles


#3

Copper tin alloys are a bit (a lot) more difficult to weld than
copper/silicon (Herculoy) bronze that I cast. Metal color matching
is much more problematic than copper/silicon alloys. BUT copper/tin
alloys are absolutely fantastic in colors that one can get via
patination. Also copper/tin alloys are known as “ancient bronze” as
it is the alloy used eons ago…

John Dach


#4
Buy your tin from a metal merchant. Why add silicon? A safe bronze
is 90/10 (90% copper, 10% tin), and if you alloy is correctly it
will make beautiful jewellery. 

Can you recommend an online metal merchant? What is the proper way to
alloy the 90/10 bronze correctly?

thank you, Andy


#5
Can you recommend an online metal merchant? What is the proper way
to alloy the 90/10 bronze correctly? 

If you’re in Sydney Australia, I can help you with the location of a
good merchant.

It’s best to find a local merchant and turn up. Online prices are
fixed, if you go to a face-to-face merchant, they may give you a
discount for being nice and talking to them. I even was offered a
job once, because I was a nice fellow and “seemed” to know what I was
talking about :smiley:

Does anyone on the list live near to you? They may know of a local
metal merchant.

The proper way, or more correctly the way I’ve found that works
well, to make 90/10 bronze is to :-

  1. Fill your crucible up with flux. Then empty the crucible, this
    leaves a coating of flux powder there-in.

  2. Put in your chunk of tin.

  3. Cover with granulated copper.

  4. Put the lot into your furnace, and melt away (3-5 minutes with no
    cross wind).

  5. You will see nothing happening, then all of a sudden the lot will
    melt.

  6. Give the metal a quick stir with a green stick, then pour into
    your mould.

** Notes:

i) Filling the crucible with flux helps the bronze to flow.

ii) Putting the tin in first lowers the melt point of the copper.

iii) The granulated copper forms a crust, and acts like a lid, which
stops your tin from evaporating.

iv) The green stick method is an old trick, that works well for
removing impurities from your melt. You take a stick from a living
tree, so it has a little moisture in it. When you stir the melt with
the green stick the impurities in the melt, stick to the stick. The
other nice thing is that the stick turns to charcoal, and can be
used as a graphite stirring rod.

The result will be a very lovely warm coloured bronze.

If you have any questions please feel free to ask.

Regards Charles

P.S. The stick is green, not turgid with water. If you use a cactus
to stir your melt you’re on your own.


#6

I’ve never tried to solder it, thanks for the heads up. It’s good to
know that it’ll be a challenge.

Ancient bronze as a term is one of the reasons I use the alloy and
it’s a joy to make.

Regards Charles

P.S. This would explain the reason why the literature says it’s
difficult to mokume bronze and fine silver.


#7
Give the metal a quick stir with a green stick, then pour into your
mould. 

Good description by Charles, and I’ve never made bronze. I make gold
all oys all the time, though, and I get better results by melting
twice - it’s not scientific, it just “feels” better and I have fewer
problems. That is, melt the alloy, cool and clean, then melt again to
cast or whatever. This is with gold, for me, and I’m not arguing,
just another tidbit.


#8

I have made and use ancient bronze for small sculpture. It is a
beautiful metal, patinates very well. I did not have to do any
welding on it so I cannot say anything here, but it might (??) TIG
weld. Just don’t know and I don’t have any to try it on. Just a
thought…

John Dach


#9
I make gold alloys all the time, though, and I get better results
by melting twice - it's not scientific, it just "feels" better and
I have fewer problems. That is, melt the alloy, cool and clean,
then melt again to cast or whatever. This is with gold, for me, and
I'm not arguing, just another tidbit. 

Unfortunately you can’t do that with bronze without losing tin,
unless you take precautions.

When re-melting bronze, to reduce tin loss, and having your bronze
going pink, you need a lidded crucible.

Brass is the same, although brass is more of a safety hazard as the
zinc in the alloy vapourises.

The best bronze is a one shot wonder… imo.

Regards Charles


#10

I have access to large amount of copper shavings, however it is
contaminated with alum. and other metal shavings. How would one go
about recovering this material?


#11
I have access to large amount of copper shavings, however it is
contaminated with alum. and other metal shavings. How would one go
about recovering this material? 

Aw that sucks. If you accidentally mix aluminium in with your copper
you will end up with “very” hard alloy.

Not sure how you would separate the swarf, I’ve never needed to.

Regards Charles


#12

And Charles, which one is that??? Actually bronze alloys with no tin
(and as far as I am concerned not zinc either) that are great and
consistent and do well with remelts. I use Everdure for the
sculptural casting I do and it maintains good color well with re-
melts and welding.

John Dach


#13
And Charles, which one is that??? Actually bronze alloys with no
tin (and as far as I am concerned not zinc either) that are great
and consistent and do well with re-melts. I use Everdure for the
sculptural casting I do and it maintains good color well with re-
melts and welding. 

90/10 definitely doesn’t look the same after a re-melt. I might be
being picky, you know where I’m coming from, but for the purpose of
the list I’ll expand my comments.

As you know alloys are mixtures of elements, this means that in the
case of 90/10 bronze, you have elemental copper and elemental tin
mixed together, they do not form another element. If they did, then
re-melting the alloy would not change its colour, and more
importantly there’d only be one recipe for bronze.

As it is when you heat a piece of 90/10 bronze the tin will
vaporise, and go elsewhere (brass is the same except using zinc and
copper), leaving a greater portion of copper.

I notice a colour change when I re-melt 90/10 bronze (I’m picky). In
fact if you keep re-melting the same bronze over and over again, in
the end you’d be left with copper.

This is not new this has been known about for
centuries. People doing re-melts in the past have had to add extra
tin to maintain the colour. Also in the past, if tin was not
available, then whatever was on hand would go into the re-melt.

Tin vaporising is an awful waste, zinc vaporising is really
dangerous, and will make you quite ill, if not kill you.

Any bronze that is re-melted will lose some of the lower melt point
elements, and colour changes can be noticeable. If alloying bronze
made an element then it wouldn’t change colour when remelted, it
would simply oxidise.

I even use this to my advantage if I want to make a faux gold. I get
a nice piece of brass, and re-melt it, some of the zinc evaporates
and you’re left with a different coloured alloy.

Let’s get a little more into the alloy recipes :-

Everdure Bronze, this is a trade name for a silicon bronze, which
technically isn’t a bronze at all (bronze needs tin in it to be a
true bronze). The alloy recipe for Everdure is 95% Copper, 4%
Silicon, and 1% Manganese. Copper is 1083C (1981F), Silicon is 1420C
(2588F), and Manganese is 1245C (2273F).

90/10 bronze, or ancient bronze, or Anglo-Saxon bronze is 90% copper
and 10% tin. As before Copper has a melt point of 1083C (1981F), and
Tin is 232C (450F).

The melt point of 90/10 bronze is greater than that of tin, so when
heated the tin turns to a vapour.

The melt point of Everdure varies with the alloy (there’s always a
plus or minus with industrial alloys). If the melt point of the
Everdure alloy is less than the lowest melt point element, then the
colour will not change. If the melt point is higher than the lowest
melt point element (and sometimes it just has to be), the colour will
change.

I hope that make sense, if not I can always answer questions :wink:

Regards Charles


#14
copper shavings, however it is contaminated with alum. and other
metal shavings. 

Hydrochloric acid - sometimes called Muriatic acid in the hardware
store will dissolve the aluminum and leave the copper behind. The
usual words about safety and fumes…

Also some “other metals”, but what other metals are you talking
about? If it’s beryllium or titanium (aerospace scrap, for instance)
then that’s so mething else again. Copper is so cheap, unless you’re
talking hundreds of pounds, that it’s probably not worth the
headaches.


#15
Everdure Bronze, this is a trade name for a silicon bronze, which
technically isn't a bronze at all (bronze needs tin in it to be a
true bronze). 

This is not really true. The terms bronze and brass are so distorted
by their long history that trying to rely on them for an accurate
description of the alloy is not wise. For example the alloy trade
named Commercial Bronze is a brass alloy with no tin in it. In the
US the CDA (Copper Development Association) is probably the main
source for alloy nomenclature and definition. By their system a
brass is a Copper Zinc alloy where zinc is the second greatest
alloying element by weight and bronze is copper with any other
element as the second most significant element with the exception of
nickel which is in a separate category of copper nickel alloys
(nickel silver, cupro-nickel etc). So there are silicon bronzes,
aluminum bronzes, titanium bronzes etc. Trade names like Silicon
Bronze, Nickel Silver and Naval Brass etc may get you close to what
they are but if you really want to define an alloy you need to refer
to it by the CDA number or other standards organization
identification as the trade names are often next to useless and metal
sold by trade name is often not what you think it is.

James Binnion
James Binnion Metal Arts


#16
Actually bronze alloys with no tin (and as far as I am concerned
not zinc either) that are great and consistent and do well with
remelts. 

Please forgive my ignorance, if it is such, but it was my
understanding that copper and tin alloys are bronze, and that with no
tin, there is no bronze, just fine copper or another copper based
alloy. I speak of metallurgical bronze, not some sales or trade name.

Mike DeBurgh, GJG
Alliance, OH


#17

Caustic soda and then rinse well should do the trick. Maybe
neutralise the alkali with some vinegar. It won’t affect the copper
but will dissolve the aluminium. Be careful when and where you do it.
Caustic soda is nasty stuff and the reaction produces hydrogen which
is just a touch flammable.

Jenny


#18
This is not really true. The terms bronze and brass are so
distorted by their long history that trying to rely on them for an
accurate description of the alloy is not wise. For example the
alloy trade named Commercial Bronze is a brass alloy with no tin in
it. In the US the CDA (Copper Development Association) is probably
the main source for alloy nomenclature and definition. By their
system a brass is a Copper Zinc alloy where zinc is the second
greatest alloying element by weight and bronze is copper with any
other element as the second most significant element with the
exception of nickel which is in a separate category of copper
nickel alloys (nickel silver, cupro-nickel etc). So there are
silicon bronzes, aluminum bronzes, titanium bronzes etc. Trade
names like Silicon Bronze, Nickel Silver and Naval Brass etc may
get you close to what they are but if you really want to define an
alloy you need to refer to it by the CDA number or other standards
organization identification as the trade names are often next to
useless and metal sold by trade name is often not what you think it
is. 

Historically Everdur is not technically a bronze because it does not
contain tin. It would however be a copper alloy.

Another name for Everdur is silicon brass, yet it has no zinc in it
either, technically it’s not a brass either. It’s a trade name for a
copper alloy, simple as that. The fact that we call it bronze is due
to marketing only.

FYI: Everdur was created in 1934 by Witton, so not an exceptionally
long history, as compared with thousands of years of bronze
manufacture. Calling a copper alloy bronze that does not contain tin
is only a relatively recent marketing ploy.

If you’re searching through, they have some excellent references to
historical bronze usage. They even have some Chinese edicts listing
the percentages of tin and copper required for the manufacture of
items from teapots to axes. The history of copper is a very
interesting read.

As I make historical replicas (amongst other things), I get very
anal about the recipes for my alloys, and the terminology needs to be
correct.

Regards Charles
P.S. Is it Aluminum or Aluminium? :-p


#19
Historically Everdur is not technically a bronze because it does
not contain tin. It would however be a copper alloy. 

If all you are interested in is historical bronze then yes it was
copper and tin with various other metals as impurities but for at
least the last 50-75 years the following definition has been in
place.

Broadly speaking, bronzes are copper alloys in which the major
alloying element is not zinc or nickel. Originally "bronze"
described alloys with tin as the only or principal alloying
element. Today, the term is generally used not by itself but with
a modifying adjective. For wrought alloys, there are four main
families of bronzes: copper- tin-phosphorus alloys (phosphor
bronzes); copper-tin- lead-phosphorus alloys (leaded phosphor
bronzes); copper-aluminum alloys (aluminum bronzes); and
copper-silicon alloys 

From the Copper Development Association website (
http://tinyurl.com/2nqgpr) (silicon bronzes).

It is not a marketing ploy but an attempt to classify various copper
alloys in a systematic fashion. Bronze alloys are a harder more
durable class of alloys than the Brasses are so it makes since to
class the aluminum, and silicon bronzes along with the phosphorus
(tin bearing) bronzes.

Jim

James Binnion
James Binnion Metal Arts


#20
I hope that make sense, if not I can always answer questions.-) 

Thanks for all the bronze It has been helpful. _ I have
been cetrifugal casting, torch melt, (oxy/propane) alloy cda#521 ,
310 grams at a cast, stirring with a graphite rod,with pretty good
results._I have been recasting the sprues,clippings etc. and noticed
the color change you referred to. (which I don’t like). question: __I
found an online metal source for 99.8% pure tin,and am going to
experiment with replacing some of the tin in the recasts. What is the
effect, if the tin I replace in the alloy makes an alloy greater than
90/10? color change, melt temperature. brittle, etc.

As soon as I find a source for copper, ( hopefully grain) I am going
to try casting, alloying directly in the crucible a 90/10 alloy.

If you care to see some of the things I have been casting,you can do
so at: oldworldbronze.com. thanks again, Andy