Ive a friend that is making a replica of the Iron age Battersea shield,
found in the river Thames in Victorian times.
Now he and I have been discussing his problem . That is the original
alloy used was copper tin 90/10. by percentage anlysis.
In other words 9 parts of copper to 1 part of tin by volume
Now he made up his alloy by weight . ie say 18 0z of copper to 2 0z
of tin.
He carefully melted the copper and added the tin, cast his ingot,
cleaned it up and proceeded to hammer it out into sheet.
It always cracked, despite repeated annealing.
So I said because tin is lighter than copper your in fact adding more
tin than 10%.
If you want a 90/10 to finish up with, you have to do the alloying by
parts. Ie volume .
I said you need say 9 1in cubes of copper to 1 1in cube of copper to get
the 90/10 result. He couldnt see that.
Now I put this to the scientific minds on REc. Crafts. Metalworking to
resolve, one way or another which is the right way to make this alloy.
This is not a scam or a troll.
What eventually happened as he had a deadline to finish it I gave him
som 70.30 brass sheet that was the same colour and was ductile enough to
do the replica.
Ted
Frater
Dorset
UK.

Ted Frater wrote:
Ive a friend that is making a replica of the Iron age Battersea shield,
found in the river Thames in Victorian times.
Now he and I have been discussing his problem . That is the original
alloy used was copper tin 90/10. by percentage anlysis.
In other words 9 parts of copper to 1 part of tin by volume
Now he made up his alloy by weight . ie say 18 0z of copper to 2 0z
of tin.
He carefully melted the copper and added the tin, cast his ingot,
cleaned it up and proceeded to hammer it out into sheet.
It always cracked, despite repeated annealing.
So I said because tin is lighter than copper your in fact adding more
tin than 10%.
If you want a 90/10 to finish up with, you have to do the alloying by
parts. Ie volume .
I said you need say 9 1in cubes of copper to 1 1in cube of copper to get
the 90/10 result. He couldnt see that.
Now I put this to the scientific minds on REc. Crafts. Metalworking to
resolve, one way or another which is the right way to make this alloy.
This is not a scam or a troll.
What eventually happened as he had a deadline to finish it I gave him
som 70.30 brass sheet that was the same colour and was ductile enough to
do the replica.
Ted
Frater
Dorset
UK.

sorry, made a mistake
its 9 1in cubes of copper to 1 1in cube of tin.

On Sat, 25 Sep 2010 17:10:21 +0100, Ted Frater
wrote:


Now he and I have been discussing his problem . That is the original
alloy used was copper tin 90/10. by percentage anlysis.
In other words 9 parts of copper to 1 part of tin by volume
Now he made up his alloy by weight . ie say 18 0z of copper to 2 0z
of tin.
He carefully melted the copper and added the tin, cast his ingot,
cleaned it up and proceeded to hammer it out into sheet.
It always cracked, despite repeated annealing.
So I said because tin is lighter than copper your in fact adding more
tin than 10%.
If you want a 90/10 to finish up with, you have to do the alloying by
parts. Ie volume .
I said you need say 9 1in cubes of copper to 1 1in cube of copper to get
the 90/10 result. He couldnt see that.
Now I put this to the scientific minds on REc. Crafts. Metalworking to
resolve, one way or another which is the right way to make this alloy.
This is not a scam or a troll.
What eventually happened as he had a deadline to finish it I gave him
som 70.30 brass sheet that was the same colour and was ductile enough to
do the replica.
Ted
Frater
Dorset
UK.

sorry, made a mistake
its 9 1in cubes of copper to 1 1in cube of tin.

Alloy composition is specified by weight, not volume, so your friend
made up the alloy in the proper proportions.

You can locate similar commercially available alloys he
http://www.matweb.com/search/CompositionSearch.aspx

--
Ned Simmons

On Sep 25, 11:10*am, Ted Frater wrote:
Ted Frater wrote:
Ive a friend that is making a replica of the Iron age Battersea shield,
found in the river Thames in Victorian times.
*Now he and I have been discussing his problem . That is the original
alloy used was copper tin 90/10. by percentage anlysis.
In other words 9 parts of copper to 1 part of tin by volume
*Now he made up his alloy by weight . ie say 18 0z of copper to 2 0z
of tin.
He carefully melted the copper and added the tin, cast his ingot,
cleaned it up and proceeded to hammer it out into sheet.
It always cracked, despite repeated annealing.
So I said *because tin is lighter than copper your in fact adding more
tin than 10%.
If you want a 90/10 to finish up with, you have to do the alloying by
parts. Ie volume .
I said you need say 9 1in cubes of copper to 1 1in cube of copper to get
the 90/10 result. He couldnt see that.
*Now I put this to the scientific minds on REc. Crafts. Metalworking to
resolve, one way or another which is the right way to make this alloy.
*This is not a scam or a troll.
What eventually happened as he had a deadline to finish it I gave him
som 70.30 brass sheet that was the same colour and was ductile enough to
do the replica.
Ted
Frater
Dorset
UK.

sorry, made a mistake
its 9 *1in cubes of copper to 1 *1in cube of tin.- Hide quoted text -

- Show quoted text -

It makes a difference if you make the alloy either by volume % or by
weight %. It sounds like you made the alloy based on volume % when
you should have made the alloy based on weight %: i.e. 9 lbs copper +_
1 lb tin. If you made the alloy based on 90% volume by weight, you
would get 91.7% copper to tin by weight.

On 9/25/2010 12:08 PM, Ted Frater wrote:
Ive a friend that is making a replica of the Iron age Battersea shield,
found in the river Thames in Victorian times.
Now he and I have been discussing his problem . That is the original
alloy used was copper tin 90/10. by percentage anlysis.
In other words 9 parts of copper to 1 part of tin by volume
Now he made up his alloy by weight . ie say 18 0z of copper to 2 0z
of tin.
He carefully melted the copper and added the tin, cast his ingot,
cleaned it up and proceeded to hammer it out into sheet.
It always cracked, despite repeated annealing.
So I said because tin is lighter than copper your in fact adding more
tin than 10%.
If you want a 90/10 to finish up with, you have to do the alloying by
parts. Ie volume .
I said you need say 9 1in cubes of copper to 1 1in cube of copper to get
the 90/10 result. He couldnt see that.
Now I put this to the scientific minds on REc. Crafts. Metalworking to
resolve, one way or another which is the right way to make this alloy.
This is not a scam or a troll.
What eventually happened as he had a deadline to finish it I gave him
som 70.30 brass sheet that was the same colour and was ductile enough to
do the replica.
Ted
Frater
Dorset
UK.


My guess is a processing problem, not a bad alloy mix. The price break
in cymbals is generally between cymbals made with 8% tin or 20% tin
alloys. 8% tin is available in sheet, and can be punched out. 20% is not
available as sheet, as it is too brittle to roll cold. If you view the
cymbal manufacturer's videos on Youtube, you will see that the 20% tin
cymbals are made from a poured alloy biscuit, rolled flat while still
red hot, being returned to the oven to anneal, and rolled more while
still red hot. It may be that your friend missed the red hot part.

Kevin Gallimore

On Sep 25, 10:08*am, Ted Frater wrote:
Ive a friend that is making a replica of the Iron age Battersea shield,
found in the river Thames in Victorian times.
* Now he and I have been discussing his problem . That is the original
alloy used was copper tin 90/10. by percentage anlysis.
In other words 9 parts of copper to 1 part of tin by volume
* Now he made up his alloy by weight . ie say 18 0z of copper to 2 0z
of tin.
He carefully melted the copper and added the tin, cast his ingot,
cleaned it up and proceeded to hammer it out into sheet.
It always cracked, despite repeated annealing.
So I said *because tin is lighter than copper your in fact adding more
tin than 10%.
If you want a 90/10 to finish up with, you have to do the alloying by
parts. Ie volume .
I said you need say 9 1in cubes of copper to 1 1in cube of copper to get
the 90/10 result. He couldnt see that.
* Now I put this to the scientific minds on REc. Crafts. Metalworking to
resolve, one way or another which is the right way to make this alloy.
* This is not a scam or a troll.
What eventually happened as he had a deadline to finish it I gave him
som 70.30 brass sheet that was the same colour and was ductile enough to
do the replica.
Ted
Frater
Dorset
UK.

Chemical analysis is always done on a weight basis, your buddy's
alloying methodology is correct. What may not be correct is
manufacturing technique. Do you know FOR SURE that such an item was
manufactured by cold-working? Is there any proof that it was done
that way? Frequently this is where modern attempts to exactly
reproduce antique items go wrong. A lot of this knowledge was never
written down, was passed on only from master to apprentice. Sounds
like that alloy is cold-short, might either need casting to exact
shape or hot-worked or cast AND hot-worked. Lost wax would probably be
the way today. Brass and copper-working techniques don't necessarily
translate to other alloys. Also, trace elements can do odd things to
cuprous alloys, how complete was the original chemical analysis?
Thinking arsenic, tellurium, selenium and maybe silicon and
phosphorus. Might have silver and gold, copper refining wasn't that
advanced to remove all traces of those, but those shouldn't do a lot
to the alloy properties.

Stan

On Sat, 25 Sep 2010 13:59:26 -0700 (PDT), wrote:

Also, trace elements can do odd things to
cuprous alloys, how complete was the original chemical analysis?
Thinking arsenic, tellurium, selenium and maybe silicon and
phosphorus. Might have silver and gold, copper refining wasn't that
advanced to remove all traces of those, but those shouldn't do a lot
to the alloy properties.

If you search for alloys close to a 90/10 composition on the matweb
link I gave, it appears that just a trace of phosphorous has a big
effect on formability.

--
Ned Simmons

Ned Simmons wrote:
On Sat, 25 Sep 2010 13:59:26 -0700 (PDT), wrote:

Also, trace elements can do odd things to
cuprous alloys, how complete was the original chemical analysis?
Thinking arsenic, tellurium, selenium and maybe silicon and
phosphorus. Might have silver and gold, copper refining wasn't that
advanced to remove all traces of those, but those shouldn't do a lot
to the alloy properties.

If you search for alloys close to a 90/10 composition on the matweb
link I gave, it appears that just a trace of phosphorous has a big
effect on formability.


Thanks everyone for your help.
One never knows it all.

The shield was on a wooden backing, with 1/2 to 1mm thick bronze sheet
raised in all sorts of Celtic designs.
The sheet would have had to be beaten out cold then raised in the
usual way .
Ted
Dorset UK.

On Sep 26, 2:19*pm, Ted Frater wrote:
...
The shield was on a wooden backing, with 1/2 to 1mm thick bronze sheet
raised in all sorts of Celtic designs.
* The sheet would have had to be beaten out cold *then raised in the
usual way .
Ted
* Dorset UK.

http://www.bellchamber.net/catalogue...rseaShield.jpg