On Sun, 26 Apr 2009 10:16:05 -0700, in rec.crafts.jewelry Muso
wrote:



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.

Not being a toolmaker, at least in that sense (when I'm making tools for my own
use, it's usually from steel), I'll take your word for it. But from curiosity,
why?


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.

I didn't say it would be superior to zinc as an arrowhead. I said the pewter
would be easier to get a good, porosity free casting from. That's all.
Remember, my approach to this is to objects used as decorative items, so the
quality of the casting affects the visual appeal. That's the main focus of my
statement.


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.


Again, no I didn't mean that pewter would make a better actual arrowhead. I
meant that making a decorative arrowhead, or spearpoint, or whatever, would be
easier in pewter, since you get a better casting. Frankly, I'd be surprised if
either pewter or zinc could produce a usable actual arrowhead in any case. I
might be wrong, of course, but I'd expect neither metal to be strong enough to
withstand the sorts of impact stresses an arrowhead would need. You are right
that pewter is likely to be softer than zinc, but I'd expect zinc to be too soft
for a good arrowhead as well. Thus I assume the aim is for a decorative item.
However, I'm not all that experienced in either making arrowheads, or functional
items in zinc, so perhaps I'm wrong, and you can go hunting or target shooting
with zinc arrowheads just fine. If so, have fun!

*Too soft...

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

Pewter is not harder than zinc. In fact, it has the unusual property of not
work hardening when you manually work it. It actually gets softer as you work
it. But as I said above, my assumption is that BOTH metals are too soft for a
good arrowhead. I might be wrong, of course. I make jewelry, not weapons, for
the most part. The little knifemaking I've done used steels, not zinc...


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.

Mistakes are not automatically painful, or even a bad thing. They're an
especially effective way to learn about not just what not to do, but why not to
do it. The pain comes from repeating mistakes one should have learned from, or
making mistakes that could have been easily avoided. Or from making mistakes
that cost an undue amount of cash... But again, experimenting and working
things out for yourself are a fine and recommended way to learn. Far superior,
I think, to just following instructions and learning a sequence of operations by
rote, without understanding them. Please, by all means, continue to
experiement. I applaud your efforts. However, do try to avoid spending too
much time re-inventing the wheel...


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.

That sand sounds a bit like the very fine grained sand packaged in a somewhat
pricey little sand casting kit called "Delft clay" casting sand. Comes with a
little mold kit. That sand too, looks very very fine grained. I think it's an
oil tempered sand, but I'm not sure. Fairly easy to use, but whomever is
repackaging it as "Delft clay" instead of it's original name (I've been told,
but don't know, that it's the same as somethign called petrobond...) is no doubt
making a good deal of cash off of jewelers not familier with commercial sand
casting materials...

Cheers

Peter