If you want some first hand knowledge about bronze and brass,
you might give Atlas Metals (303-623-0143 in Denver Colorado).
Dave is very helpful and knows a bunch!!! Do/did WE really
collect and ship those shell casings back from "the wars"
mentioned above?? As far as I know, most of that materials is
left where it fell and ultimately, if used at all, is picked up
and used by the “locals”. Most good casting metals are “newly"
smelted and alloyed metals, not “old”, unknown metal mixes.
There is too much to loose in expensive castings to save a few
pennies on unknown materials verses new, known materials. I cast
Everdure Bronze for sculptures, and I would not use anything that
could cause un necessary and un needed defects. There are metals
that are not made anymore (true wrought iron for one) but I bet
that Atlas and other metal suppliers have and can supply you with
"Clock Brass” or other metal alloys as needed.
My 2c worth.
MidLife Crisis Enterprises
Cynthias sculptures are at: http://www.mlce.net
A small bronze foundry, no web site yet!!