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JeffEvarts

Bronze hardness/tooling (Wrong forum?)

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Hello.

I'm interested in historical metallurgy, and I have a question about differing types of bronzes, specifically copper/tin and copper/arsenic.

I cannot seem to find any information about producing harder flavors of bronze (preferably without resorting to zinc/brass).

Anyone know specific copper/tin or copper/arsenic alloys that could be used to make tools to work cast bronze (90/10 or 88/12)?

-Jeff

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This is the correct forum, but we only have a couple of bronze age folk who hang around here, Jeroen Zuiderwick being the primary one.  Hopefully he will see this and respond, but he has been busy elsewhere lately.  I'd like to know that as well!  Ibor from Poland may be helpful as well, and he's been here today.  You might try sending them a PM and ask them to reply here, it is a worthwhile topic.

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I think a little more information might be helpful here.  Are you looking to make your own alloys from raw materials, or are you hoping to buy a bar of a pre-made (e.g. ASTM) alloy?  And how open are you to other alloying elements than tin and arsenic?  

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On 7/21/2018 at 9:38 PM, JeffEvarts said:

Hello.

I'm interested in historical metallurgy, and I have a question about differing types of bronzes, specifically copper/tin and copper/arsenic.

I cannot seem to find any information about producing harder flavors of bronze (preferably without resorting to zinc/brass).

Anyone know specific copper/tin or copper/arsenic alloys that could be used to make tools to work cast bronze (90/10 or 88/12)?

-Jeff

You basically harden bronze by workhardening. The more you hammer it, the harder it gets, until it cracks. Bronze with higher tin or arsenic contents starts off harder as cast, and can be workhardened to a higher hardness. But it also gets more brittle, so it cracks easier. What kind of work do you want to do? Punches for decorating work well. But you simply can't carve bronze with bronze tools. No bronze will give you an edge that will allow you to carve bronze or drill it. You can make a chisel for cutting off flashing, but you will need to restore the edge of that continuously. 

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Posted (edited)
On 7/25/2018 at 12:15 AM, Jeroen Zuiderwijk said:

 Punches for decorating work well. But you simply can't carve bronze with bronze tools. No bronze will give you an edge that will allow you to carve bronze or drill it. You can make a chisel for cutting off flashing, but you will need to restore the edge of that continuously. 

Jeroen, THANK YOU for replying!

I had hoped to make a scraper for making (cast) surfaces flatter or rounder. Making a cylinder more round or a flat-dyed surface more flat. A bronze-on-bronze version of this ferrous-on-ferrous example. Do you think such a tool could be made? I am happy to use different formulations of bronze in the worked surfaces and the tool. If it's even remotely possible, I'm willing to give it a try.

It seems intuitive that they must have worked bronze artifacts with SOMETHING before they had iron tools. Perhaps they used stone or meteoric iron?

-Jeff Evarts

Edited by JeffEvarts

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Posted (edited)

Jerrod and Alan: Thank you for replying as well. I am going to be combining (and casting) the metals myself, or at least that's the plan for now. Buying ASTM stock isn't off  the menu entirely, but it's not what I had in mind. Other alloys are possible provided they were available before iron hit the scene. (Cu,Sn,As,Ag,Au,Pb)

Wikipedia (and other sources) say that bronze is harder than cast iron (VH 60–258) and 30/70 Cu/Ag goes to 90. Perhaps a silver alloy tool?

-Jeff Evarts

Edited by JeffEvarts

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10 hours ago, JeffEvarts said:

Jeroen, THANK YOU for replying!

I had hoped to make a scraper for making (cast) surfaces flatter or rounder. Making a cylinder more round or a flat-dyed surface more flat. A bronze-on-bronze version of this ferrous-on-ferrous example. Do you think such a tool could be made? I am happy to use different formulations of bronze in the worked surfaces and the tool. If it's even remotely possible, I'm willing to give it a try.

It seems intuitive that they must have worked bronze artifacts with SOMETHING before they had iron tools. Perhaps they used stone or meteoric iron?

-Jeff Evarts

Meteoric iron can not be hardened, and was only available in extremely small amounts in the near east. And there it was valued much higher then gold. What they used in the bronze age was stones, simple polishing compounds (f.e. clay), and occasionally bronze hammers and possibly burnishing tools (stone or bronze). Not even the finest polishing stones, just whatever you could find locally. Smooth stones were also frequently used as hammers/anvils. It's all very laborous, but it does work. But the most important thing was to get a good casting in the first place. 

The oldest metal tools for finishing metal objects that I know are files at the very end of the iron age. It's quite possible that steel scrapers were already in use for some time. However, hardened steel isn't really common until the end of the iron age. Most iron was just soft iron until then.

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Not that this applies directly to the topic, but tools made of meteoric iron were used in the new world at least occasionally.  There was a huge meteorite at Cape York in the Canadian arctic ( or there was until Admiral Perry decided to steal them) that the natives hammered pieces off of and made things out of the chunks.   Cape York

 

I think it likely that early iron tools were simply used until there was nothing left, and so their foot print is very small.

 

Geoff

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That is true, but meteoric iron is a lot softer than bronze.  

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22 hours ago, Alan Longmire said:

That is true, but meteoric iron is a lot softer than bronze.  

Ahh, the voice of knowledge. Thank you Alan.

And since nobody "bit" on the silver tool angle, I'm going to assume that's impractical as well.

On 7/28/2018 at 5:28 AM, Jeroen Zuiderwijk said:

What they used in the bronze age was stones, simple polishing compounds (f.e. clay), and occasionally bronze hammers and possibly burnishing tools (stone or bronze). 

The oldest metal tools for finishing metal objects that I know are files at the very end of the iron age.

How did they drill a (deeper 1:5 or 1:10) hole in bronze, then? Or did they just 'not do that'? :)

More in hope than expectation, does this mean that I could (practically) scrape a flat or cylinder using a bronze-on-bronze (perhaps hammered-hard on heated/annealed) system? Labor time is not a problem in this case.

Thanks for the replies everyone, this has been a good conversation.

-Jeff

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Posted (edited)
On 7/29/2018 at 9:26 PM, JeffEvarts said:

How did they drill a (deeper 1:5 or 1:10) hole in bronze, then? Or did they just 'not do that'? :)

They did. And the answer to the question how is: nobody knows ;) 

One alternative way rather then drilling is punching. Take a punch, and strike a small dimpel. Then anneal and do it again. As soon as the material on the opposite face starts to bulge, grind that off. Keep on doing that until you're all the way through. I've done this, and it works, sort off, if you are careful and not crack the piece.  The real trick is the large holes in thin sections. One method proposed is to use a bronze tube along with an abbrasive, such as fine sand. That would be similar to how they drilled through stone, except there they either used bone or hollow hardwood tubes. 

Edited by Jeroen Zuiderwijk

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On 7/29/2018 at 9:26 PM, JeffEvarts said:

More in hope than expectation, does this mean that I could (practically) scrape a flat or cylinder using a bronze-on-bronze (perhaps hammered-hard on heated/annealed) system? Labor time is not a problem in this case.

In theory maybe. I've used a 20% tin bronze scraper once. With 20% tin, the bronze is very hard and brittle in as cast state. It can't be work hardened, only made more tough by annealing. However after one or two small scrapes it lost it's edge, so it had to be resharpened. So it's just not practical in use. Alteratively you can do the same with flint. Two problems there however, is that every edge of a flint flake has a different shape edge, and it will dull nearly as quickly as the bronze. 

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1 minute ago, Jeroen Zuiderwijk said:

In theory maybe. I've used a 20% tin bronze scraper once. With 20% tin, the bronze is very hard and brittle in as cast state. It can't be work hardened, only made more tough by annealing. However after one or two small scrapes it lost it's edge, so it had to be resharpened. So it's just not practical in use. Alteratively you can do the same with flint. Two problems there however, is that every edge of a flint flake has a different shape edge, and it will dull nearly as quickly as the bronze. 

Worth noting is that I didn't experiment any further after that. I just didn't see any advantage over planishing by hammer(stone) and further polishing with stones and other compounds. 

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On 7/31/2018 at 4:02 AM, Jeroen Zuiderwijk said:

They did. And the answer to the question how is: nobody knows ;) 

 

Awesome. New ground to cover.

BTW: It looks like 1500bc.com is dead. None of those links have resolved for a week or more.

Thank you, Jeroen.

Cheers,

-Jeff

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On ‎8‎/‎3‎/‎2018 at 8:46 PM, JeffEvarts said:

Awesome. New ground to cover.

BTW: It looks like 1500bc.com is dead. None of those links have resolved for a week or more.

Thank you, Jeroen.

Cheers,

-Jeff

Ah, I should update my signature. I've cancelled my websites due to rising costs, so I now only use my facebook page.

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