On Apr 22, 12:40*am, Peter W. Rowe
wrote:
On Wed, 22 Apr 2009 00:26:48 -0700, in rec.crafts.jewelry Muso

wrote:

Hello again, Peter. *I have the book "The Charcoal Foundry", by Dave
Gingery, and the book does mention about the dross. *I was holding the
torch with my left hand, though, and the spoon with my right hand, and
I wasn't sure how much working time I had to work with, so I just put
the metal in the mold dross and all. *I've decided to build a holder
for my torch, though, now that it is clear to me that such a holder
will be useful. *I probably will build a holder for my new three-
tablespoon capacity stainless steel ladle, also.

Larger quantities help. *Also, as I've mentioned before, especially with your
fairly low tech melting/casting facilties, you'll have much better resuts with
tin based alloy, rather than zinc. *That means, essentially, pewter, which
generally is essentially pure tin, with a trace of antimony an/or copper to
slightly harden it. *melting temps are similar to zinc, and the cost is not very
different either, but it melts and casts a LOT more easily. *It's routine for
those metalsmiths working with pewter to melt it in fairly informal equipment,
even down to just melting it in a tin can over a hot stove. *(steel can.
Stainless seamless pot works better) *can be cast into molds made of wood
(limited use, but it's a classic for pewter workers needing to make the cast
handles for pewter teapots and the like), or well dried plaster of paris (fine
for pewter, not good for higher melting metals, where you can use the similar
looking, but temperature resisting, casting investments used for lost wax
casting.), not to mention sand molds, or almost anything else you can dream up
that won't burn quickly. * As I've mentioned before, one good source for white
metals for casting (or in sheet and wire), including but not limited to pewter,
is the Contenti company (www.contenti.com).

Hello again, Peter. As you know, I like to use scrap metal, and if I
wanted a refined metal, I would do the job myself. My point of view
about this has not changed. I don't expect that I would find very
much scrap tin around, though, since tin is outrageously expensive
anyway. Scrap zinc is available, though, and for tool making zinc is
better than tin regardless.

Yes, I worked on that arrow head for a long time with my file, but I
still ended up with some pits and cracks. *I think that with practice,
though, I should be able to get much better results. *I ended up with
a good functional arrow head, but from an appearance standpoint, not
so hot.

The zinc not only incorporated the mixed in cross, but also likely absorbed a
good deal of atmospheric gasses, which also leads to pits and pinholes galore.
Again, this is another area where pewter or other tine alloys are far superior

Peter, that you would consider pewter superior to zinc for an
arrowhead is amusing to me. I see no reason why a functional
arrowhead could not be made from pewter, but that such an arrowhead
should be superior to zinc? I don't think so.

As far as "functional", well, I'd assume you mean in terms of visual shape. *I
doubt a zinc arrowhead would work so well at the end of an actual arrow.

But pewter would? You have offered no reason that I can see.

*Too soft...

And pewter is harder than zinc? I don't follow your reasoning.

I think that my mother must have remembered me joking about Twenty
Mule Team Borax, because we now have some in the laundry room.

20 mule team borax is a great way to buy the stuff cheap. *But note that borax
is best as a flux for higher melting alloys, like brass, bronze, silver, gold,
etc. *It isn't the right stuff for tin, zinc, or lead alloys.

Okay, well, I'll remember that then.

*They melt at too
low a temp, before the borax becomes properly effective.

Right now I'm long on theory, but short on experience.

Books are a great way to start. *So is actual experience, especially making
mistakes. *Reading the books carefully, though, and not then ignoring what they
say, can help minimize the frequency and pain of the mistakes...

My "mistakes" have not been painful. The first cast was not meant to
be perfect, though I could easily make it that way. I'm just ready to
move on. Today I bought some wood and string to weigh out the sand to
make the mold to cast my first spear head.

I bought some beeswax today, and some silica sand to add to my
fireclay. *In retrospect, it looks like I already had some sand, but
it is so fine-grained that I thought it was clay. *I now have three
hundred pounds of sand, and fifty pounds of fireclay. *Later, I will
get some coarse silica sand, and some bentonite clay.

Sounds like you're on your way to doing large sculptural sized sand castings.
You might have to learn how to melt bronze at that rate... (grin)

Cheers

Peter Rowe

Actually, the quantity is misleading. The sand is so fine-grained (60
mesh to 80 mesh) that I was unsure that it was even sand at all. I
could have just added water, of course, but, anyway, when I went back
for another bag, the worker threw in an extra third bag, which was
just as difficult to unload as the second. Anyway, I am making
progress, and I am happy. I will not be moving on to brass for
awhile, though I am interested in lost wax.

Mike Mandaville
Bee Cave, Texas