"F. George McDuffee" wrote in message
...
On Fri, 31 Oct 2008 21:38:22 -0700 (PDT), Dar
wrote:

I need to make a bunch of molds in sandcast bronze and would like to
know the kind of sand
to get for finest detail/smoothest finish . They won't be complex , or
even 2 part sand molds, probably just bronze poured onto a flat cope
that has an depression in it and a dam built around the depression .

thanks

DS
I would consider plaster molds for best detail

see
http://www.modernsculpture.com/bronze.htm


It's good to make a point of the fact that you have to know what you're
doing to use plaster molds for bronze temperatures, or you're in for an
explosion.

It will need a high-temperature mixture, probably containing vermiculite or
some modern ceramic replacement, and it will have to be calcined. "Bone dry"
isn't dry enough. You have to drive off some of the chemically retained
water.

Another option is green sand dusted with plumbago (graphite powder). That is
said to be capable of reproducing a person's fingerprint. I've seen some
aluminum castings done that way and they look almost like investment
castings.

--
Ed Huntress