As far as I know, even replacement reeds in old brass-reeded instruments are either made of steel or taken whole from another old instrument. I myself have made a few brass reeds individually by hand, but the brass sheet I used was made specially for me by a craftsman friend, using a formula for "reed brass" from a 19th-century book.
This probably should not have been in the Buy-Sell forum ( http://www.concertin...p?showtopic=282 ):
What is the 19th century formula (approximately)? Is it like Phosphor Bronze? Was the sheet rolled to spring temper?
What's the "smiley" for a puzzled expression? I thought I had answered this question already a while back. Well, maybe not.
I lost touch with the fellow who made the brass many years back, and I have no idea what the formula was. I have no idea how close it might have been to original concertina reeds, and I'm sure there have been many formulas for reed or spring brass over history, just as there are for spring steel. Nor do I know what sort of tempering or other processing he used, except that he rolled the brass into small sheets. The thickness ranged from standard reed thickness to about double that. The thinner stuff seemed to be more "spring tempered" in behavior.
I do have a little left, so if there's anyone here with the laboratory facilities to compare chemical and physical composition between that and an original reed, I might let them have a little. But I'll be very restrictive about that; I don't want to waste it on somebody who has the curiosity but not the analytical capability. (How about convincing me by sending me your analyisis of an actual brass concertina reed, first?)
In the meantime, I might suggest that anyone interested in making brass reeds, if they can't find a modern maker of spring brass, should look in university technical libraries for 19th-century books on the subject.