Making brass and bronze

[Martin FaulknerParticipant @martinfaulkner67684]

Evening all,

I have a lot of copper cable and brass fittings. I need to make some bronze bushes but looking online for bronze billets are expensive. Has anyone tried mixing their own alloys? Any tips for doing it?

[Martin FaulknerParticipant @martinfaulkner67684]

[Brian Sweeting 2Participant @briansweeting2]

Bronze is an alloy mainly if copper and tin.

If you trust Youtube then there are a fair few clips showing how to do it.

Edited By Brian Sweeting on 22/02/2018 19:53:53

[vintagengineerParticipant @vintagengineer]

I make my own solder. First I melt the required quantity of lead and the add the required quantity of tin, then cast it into sticks.

Forget the brass as this contains zinc. Get hold of some pewter tankards (90% Tin), melt your copper then add the tin.

[Neil WyattModerator @neilwyatt]

Might be easier to dissolve copper in molten tin.

Not sure you want to go adding raw phosphorus though…

Neil

Edited By Neil Wyatt on 22/02/2018 21:03:58

[Paul LousickParticipant @paullousick59116]

There are different types of bronze. Not all are suitable for making bushes.

What diameter do you need. Lots of different sizes available on ebay.

Paul

[vintagengineerParticipant @vintagengineer]

Copper melting point 1085C Tin 232C. Won't have much tin left!

Posted by Neil Wyatt on 22/02/2018 21:03:03:

Might be easier to dissolve copper in molten tin.

Not sure you want to go adding raw phosphorus though…

Neil

Edited By Neil Wyatt on 22/02/2018 21:03:58

[Neil WyattModerator @neilwyatt]

Posted by vintagengineer on 22/02/2018 21:30:54:

Copper melting point 1085C Tin 232C. Won't have much tin left!

Copper starts dissolving rapidly in tin at about 450C, a darn site easier to do than melt copper.

How do you think people did it in the bronze age?

Neil

[Alan Johnson 7Participant @alanjohnson7]

Be careful about pewter. Not all pewter is created equal! Pewter is: tin with copper and antimony (formerly, tin and lead).

I blend lead, tin and antimony to cast projectiles. Mostly adding tin and or lead to existing lead tin antimony alloys to vary the hardness of the alloy. As antomony melts at a much higher temperature (630c) than tin or lead I have read that the way to blend in antimony is placed the antimony on the top of the melt and using a propane torch heat the antimony until it melts into the alloy. I have not tried this as it seems to me to be frought with danger!

I don't know if this is relevent, but I have a friend who occassionally melts bronze for casting sculptures. I remember him saying the melt needs to be continually stirred to prevent the alloy from separating.

Alan.

[HopperParticipant @hopper]

You'll spend more on a furnace, gas burners, gas, crucibles, ladles, protective gloves, apron, goggles etc etc than the cost of a couple of bars of brass from a metals supplier. Sell your copper cable and brass fittings to a scrappie and spend the change on the brass bar.

[SillyOldDufferModerator @sillyoldduffer]

Posted by Neil Wyatt on 22/02/2018 21:57:57:

Posted by vintagengineer on 22/02/2018 21:30:54:

Copper melting point 1085C Tin 232C. Won't have much tin left!

Copper starts dissolving rapidly in tin at about 450C, a darn site easier to do than melt copper.

How do you think people did it in the bronze age?

Neil

Brass is, I think, much harder to make than Bronze.

Originally it was made by mixing 3-parts of Copper granules 'beanshot', to 1-part of calcined calamine (Zinc Carbonate) in a crucible and exposing them to 'bright ignition'. The process was hit and miss and highly skilled; the worker was dealing with impure ingredients. Much depended on the local ore.

In 1791 James Emerson patented a process for making brass directly from Zinc(1 part) and Copper (2-parts). His 8 to 10 hour process involved plunging slips of copper into molten zinc, and then raising the heat to dissolve the rest of the copper. After cooling the first melt is broken into pieces, mixed with more Zinc and thoroughly stirred before being cast into an ingot in a graphite or granite mould. (Graphite preferred.) The second melt is important; it much improves the quality of the alloy!

Later the Victorians improved brass by first melting the copper, cautiously adding the zinc, and then stirring. This avoids the need for a second melt plus it's easier to control the exact mix to produce different types of brass. I believe most modern alloying is done by starting with the metal having the highest melting point and working down to the lowest, adjusting temperature as necessary throughout. The reason is unclear. As it's harder to melt metals that way it must be important. I think it's because the metals mix better that way round.

Digging into this revealed blurred ideas in the past about Brass and Bronze. Ancient 'brass' is bronze. An alloy of Iron, copper and calamine, – a form of gun-metal – was once called brass. On the continent brass usually meant bronze. It's also possible to have a brass with tin it and a bronze with zinc in it. These days it's 'Brass' if it's Copper and mostly Zinc, and 'Bronze' if it's Copper and mostly Tin. There are multiple different brasses and bronzes.

The meaning of 'gun-metal' seems similarly blurred. The colour 'gun-metal' is a steel-blue, whereas 'gun-metal' is a copper alloy. I think it's because 'gun-metal' originally meant the metal from which guns are made, rather than a particular material. So depending on the period and country 'gun-metal' might refer to Brass, Bronze, Cast-Iron, or Steel.

Zinc is volatile and the fumes are dangerous. Modern Brass may contain small quantities of lead and cadmium, which are also toxic. Ditto Bronze which might also contain Phosphorous. Like cannabis, it's best not to inhale…

Dave

[Neil WyattModerator @neilwyatt]

Tin is particularly good at dissolving some metals – copper, gold, silver. This makes it the logical place for making straight tin bronzes.

Brass is another beast because of zinc's love of catching fire.

Strange etymological point. Just as 'all' iron dominated alloys are steels, 'all' copper dominated alloys are bronzes – except when they are brass…

Neil

[Clive HartlandParticipant @clivehartland94829]

As an aside Victoria Crosses are made from a Bronze Russian cannon from the Crimea war. The Charge of the Light brigade era.

[richardandtracyParticipant @richardandtracy]

Posted by Hopper on 23/02/2018 07:06:12:

You'll spend more on a furnace, gas burners, gas, crucibles, ladles, protective gloves, apron, goggles etc etc than the cost of a couple of bars of brass from a metals supplier. Sell your copper cable and brass fittings to a scrappie and spend the change on the brass bar.

There is no need to spend a fortune on a furnace. To replace my entire furnace, fuel, sand & casting stuff would cost anything up to £5 depending on how much scrap there is locally to clear up. I could cast bronze & pewter, but have not. I do cast aluminium. The fuel I use is pallets or an old hardwood conservatory. I have used house coal and charcoal, but have to pay for them so avoid it except in extremis. A welding apron, welding gauntlets and steel toecap boots are adequate for small quantities of aluminium and similar, and how many of us don't have them? If you don't, you should…

Regards

Richard.

[vintagengineerParticipant @vintagengineer]

I work a lot on vintage cars and what appears to aluminium castings are in fact ali zinc alloy. The foundries used to melt the ali then bulk it out with cheaper zinc. It is a real bugger to weld!

[Barnabas TaylorParticipant @barnabastaylor89961]

I have not tried making my own Bronze/Brass yet (Give me time!). I have got a small home-made furnace made from the tank of a weed burner and a home made burner however, so the cost of home casting need not be great. It is easily capable of melting copper and bronze so should be happy to meld an alloy or two.

[MWParticipant @mw27036]

Posted by vintagengineer on 23/02/2018 14:48:19:

I work a lot on vintage cars and what appears to aluminium castings are in fact ali zinc alloy. The foundries used to melt the ali then bulk it out with cheaper zinc. It is a real bugger to weld!

Hmm, well I do know they frequently alloy aluminium in order to make it harder, so i'm not sure if it isn't for structural reasons rather than cost,

Michael W

[Russell EberhardtParticipant @russelleberhardt48058]

Posted by Michael-w on 26/02/2018 07:45:18:

Posted by vintagengineer on 23/02/2018 14:48:19:

I work a lot on vintage cars and what appears to aluminium castings are in fact ali zinc alloy. The foundries used to melt the ali then bulk it out with cheaper zinc. It is a real bugger to weld!

Hmm, well I do know they frequently alloy aluminium in order to make it harder, so i'm not sure if it isn't for structural reasons rather than cost,

Michael W

It's more likely MAZAC (also known as ZAMAC) which is a low melting point alloy for die-casting. Although I thought that was introduced on 1930s rather than vintage cars.

Russell

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