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Casting Rio's Ancient Bronze

I just bought a pound of Rio Grande’s “Ancient Bronze” casting grain
for experimentation. I’m thinking of using it either as a supplement
to my line of silver animal charms, or just to cast my one-offs and
test carvings for mold-making. Before I set about ruining things,
I’d appreciate any suggestions anyone might have on working with
this stuff. Thanks in advance!

Kathy Johnson
Feathered Gems Pet Jewelry

If it is true Ancient Bronze, it is a mixture of copper and tin. Can
be reactive to skin oils/acids and the high copper can create a
problem with some molding rubbers via the copper salts that will form
on the surface and inhibit RTV catalization (giving you a sticky mold

Do some testing before you go crazy with it.

John Dach


I use it both in my historical line, and for my students. There’s
nothing tricky about it. Other than a slight color difference, it
handles a lot like Everdur or Herculoy. (Two more ‘standard’ jewelry
bronzes. They’ve both got Zinc in them, so they’re technically red
brasses, but that’s another argument.)

It’s a little on the viscous side when casting, but nothing
horrible. (Molten silver is about as runny as milk, while most
bronzes are closer to real (thin) maple syrup, if that makes any
sense. It’s on the thicker end of that scale.) Works just fine with
either centrifuge or vacuum casting. It’s more formable than standard
bronzes due to the fact that it really is a bronze, and thus has
no zinc to harden it. I’m not sure what you’re doing with it, so I
don’t know what else to tell you. Do not fear it. Play, and learn.

For whatever that all’s worth.


Just to clear one thing you stated about Everdure having zinc in it.
It doesn’t, just Herculoy does. Everdure is very easy to weld (TIG
mostly) as no zinc and it is a bit healthier to melt and work with
because of the lack of zinc. Everdure is a bit more difficult to
patinate than Herculoy, again because it it, Everdure, does not
contain any reactive zinc. As to coloration of any of these 3
alloys, ancient bronze can give some absolutely beautiful reds and
oranges compared to the Everdure or Herculoy. All of these alloys
art “thicker” than silver when poured, but the zinc in Herculoy does
make for a bit easier casting.

John Dach