Peter W. Rowe wrote:
On Sat, 20 Jun 2009 21:32:00 -0700, in rec.crafts.jewelry Limpy
wrote:

I know there's a way to do this, but I can't remember how.
I have x dwt's of sterling silver.
I want to know how much that weight of sterling will weigh in 14, 18k.
(snip)
What I assume you want is to know what the save VOLUME of the other metals would
weigh, such as if you have a casting in sterling that weighs x, how much would
that same model, cast in another metal, then weigh.

Right?
(snip)

Heres a question for you Peter,
whilst were on the subject of alloys.

My friend John Fenn is a master silver smith. Creates miracles from
nothing with almost no tools.
Cleverer than me by far.
He was asked to make a replica of the Battersea shield.
Being the determined person he is he checked out what the original alloy
ot tin and copper was.
According to the analysis made by the British Museum the last time they
did a detailed study of the shield the tin /copper ratio was between 9
and 10 %.
So John being the person he is he tried to purchase this alloy in
sheet form, 1mm thick.
It is no longer made by any Co.
So he desided to make it himself.
No problem getting pure tin and pure copper, neither a problem for him
to melt and cast a suitable ingot to start with.
However often he tried he found it would become too brittle at those
percentages to forge out into sheet despite repeated annealing.
By reducing the tin to 6% it worked fine.
so he and i discussed this problem of percentages of metals.
If the analysis by the British museum was 10% tin to copper, it had to
be by volume ie you take for example 10 1in cubes of tin and add this to
90 1in cubes of copper.
However this isnt 10 % by weight is it?
So to get the final alloy of say 10% by analysis does one go by weight
or does one go by volume?
Ie do you take say 9lbsof copper and add 1ld of tin to make the 10lbs or
100%?
We asked IMI who list this alloy tho dont make it anymore and they didnt
know anyone in their Co. who had the answer when we called.
Since John had a deadline to finish the shied, for a television
programme, I had here some 2ft by 4ft sheets of 70 /30 copper zinc I
sent him and he made it out of that. .
If you want to finish up with va 10% tin to 90% copper
So what is it? ,

By weight?
or
By volume?

ted.