On Sat, 1 Nov 2008 09:56:09 -0400, the infamous "Ed Huntress"
scrawled the following:


"Larry Jaques" wrote in message
.. .
On Sat, 01 Nov 2008 01:23:16 -0500, the infamous Tim Wescott
scrawled the following:

On Fri, 31 Oct 2008 22:59:53 -0600, F. George McDuffee wrote:

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

I've only ever used plaster molds (a long time ago, molding bullets for
miniature cannon out of solder. It's a wonder I'm still alive).

Were they still wet and exploded on you? There's a very good reason
the molds are seasoned in the furnace, Tim, as you found out.

It's not just "seasoning." First you have to dry out the free water. Then
you have to drive off a percentage of the chemically retained water. That's
called "calcining." For casting zinc or aluminum, it doesn't take much. For
casting brass or bronze, it's critical, and requires more heat.

It's not something to do by guess and by gosh. Those things can explode in a
serious way. Furthermore, ordinary Plaster of Paris will not do for casting
brass or bronze. You need special high-temperature casting plaster.

Yeah. The last book on that was a few years ago, Langland's _From Clay
to Bronze_. It convinced me that bronze sculpting was too much work.


--
Everything I did in my life that was worthwhile I caught hell for.
-- Earl Warren