I'll point out that there are some few people who can solder it -
some on Orchid have talked about doing it well. It's near
impossible for most mortals.....
I suspect it’s mostly a matter of what you’re attempting to solder
it with. Ordinary gold or silver solders and the like, as well as
normal brazing fluxes for gold or silver work, won’t work with
aluminum. But back when I was in grad school, one of the other grads,
as a research project, did a bunch of inquiry into just this. What he
found were industrially available brazing rods made for aluminum,
that then worked just fine. Flux coated rods of a special aluminum
based alloy, they worked like solder without other flux, with a
torch. Color match, as I recall was acceptable. Now that was 20 years
ago, but I assume such materials are still available.
Welding, both TIG and a few other methods, work fine, with suitable
And capacative disharge fusion welders, like the Sparkie family of
welders, can put all sorts of findings in other metals (gold, silver,
stainless, etc) onto aluminum.
Back in that same school studio, the students often worked with
casting aluminum, as well as anodizing the results. To do that, they
used a specific alloy designed to be compatible with both casting,
and anodizing. As others have noted, most aluminum alloys designed
for anodizing, don’t cast well, and vice versa. But there are
exceptions specifically made to allow both. There are also casting
investments made that are better suited to aluminum casting than
standard gold/silver investments. The main difference is that they
were much easier to remove after casting. We were using a pretty
standard vacuum casting machine, melting the aluminum on a gas
melting furnace. Mostly we did big flasks, 4 x 6 and larger, so it
was usually a fair volume of metal, which seemed to help the quality
of the castings.
In general, aluminum is pretty easy to work in many of the same ways
as silver. The main differences are the light weight, the wonderful
color possibilities available with anodizing, the low cost of the
material, and the limitations on joining. You can use any manner of
cold joints (rivets, screws, etc), as well as a number of methods of
welding and even brazing with the right materials. But it’s not a
simple matter of just ordering different flux and solder and
proceeding to fabricate things the same as you would with silver.
You may have to do some experimenting to work out methods and design
ideas that work with this different and interesting material, and for
welding or brazing, you may need different equipment too. If you
stick with “cold” joints, the learning curve will be simple.
Anodizing too, can be simpler than it may seem. You do need some
equipment, but it does not need to be extremely complex. You can
even send work out to be anodized, which merely builds up a porous
oxide film on the surface that can accept a dye. You’d then do your
own coloring if you wish, and the sealing step afterwards (easy, you
boil it in salt water) which seals in the color and makes that oxide
layer pretty impervious. Doing it this way avoids the whole anodizing
sequence, with coustic chemicals, power supplies, and the like, so
then it’s really simple. Dyes used are usually made expecially for
the purpose, but even things like colored marker ink will penetrate
the unsealed anodic coating, and after sealing, it’s pretty permanent
(especially if the dye you use is light fast so it doesn’t fade. Not
all markers fit that requiremet).
Hope that helps.