If it’s not one thing, it’s another the price of silver has dropped
recently but people are reluctant to spend due to economic pressures.
So, again I am thinking of working more with alternative metals. As I
haven’t been able to find previous examples of original, handmade
jewellery incorporating cast aluminium, I am wondering if that is
because it has been regarded as too cheap, and thus unattractive, or
is there a technical reason why people haven’t cast aluminium into
cuttlefish and then, say, anodised it?
Never tried cuttlefish casting aluminum. It’d probably work
reasonably well.
I have memories from college of watching one of the grads try to
anodize cast aluminum, and tearing his hair out because it didn’t
anodize evenly. Wasn’t my thing, so I didn’t pay too much attention,
but I do remember the bald patches. (Something about casting alloys
not being good anodizing alloys in the first place, combined with
spots of uneven oxide thickness, from what I remember.)
Meanwhile, the reason most people don’t mess with aluminum in a
jewelry studio is that it’ll contaminate your gear, and cause serious problems when you switch back to silver & gold. You’ve
heard all the warnings about keeping lead & niello completely
segregated? Aluminum has the same problem: it melts at a very low
temperature, and if you have a speck of aluminum on your silver (or
gold) when you go to hard solder it, the aluminum will alloy in, and
create a low-melting alloy on the spot, which will then grow like
leprosy, gobbling up your piece as it goes. If there’s a speck of it
in your soldering pan, or stuck to a file, you’re hosed.
That, and most people won’t pay enough for “cheap” aluminum jewelry
to make it worth the extra hassle. (Especially if you’re planning on
doing your own anodizing. You might want to check into the costs of
getting, and then disposing of sulfuric acid.)
I tried casting aluminium at uni some years ago. It wasn’t easy to
get a good result and my memory is that this was because its such a
light metal: heavier metals are much easier to get a good flow with.
I also found that anodising individual pieces is very time consuming
and hence expensive. And there’s a limit to what people will pay for
a non-precious metal. I suspect that working with pre-anodised sheet
is the only way to make it pay, sadly.
If you decide to go ahead with Aluminum, I can recommend a
refractory that’s made specifically for aluminum casting. It is
Hydroperm from US Gypsum. It’s relatively inexpensive and easy to
use.
Hydroperm is formulated so that air can be whipped into it for
permeable and lightweight castings of non-ferrous metals. I’ve used
it for casting glass to 1600F both with and without adding air. Both
types of castings are successful but the no-air method makes for
denser and stronger open-faced molds that can potentially be reused a
couple of times. Air-added molds are only strong enough for one use.
If you’re going to carve directly into the refractory after it has
set, then mix it without whipping in air. Otherwise the tiny bubbles
create pits along any surfaces you carve into the material.