How does Aluminum do when soldiered? Does it work ok? Will Silver
Aluminum is a very different metal from silver. One key difference
is that it has an extreme affinity for oxygen. Any aluminum exposed
surface forms an instant, impervious oxide layer, which then prevents
further oxygen from reaching the surface, and this is why the metal
retains it’s metallic nature. But that oxide layer prevents normal
soldering. Silver or gold solders will not work at all. In fact,
many of them melt at a higher temp than the aluminum itself, which
wouldn’t do you much good.
however, there ARE solders designed for aluminum. Generally they are
a combination of a fairly solid stick of the solder, and a specially
formulated flux. In use, you “scrub” the solder stick onto the joint,
which mechanically helps the flux displace that very tough oxide layer
enough for the solder to stick. The solders behave much more like the
tin based solders we jewelers call “soft” or “lead” solders. But they
do work. Still, these things usually are designed for repairing your
porch railing, not making jewelry scale objects. If you’re thinking
of carefully placing little paillons of aluminum solder around your
aluminum bezel while you solder it to your aluminum ring, you’re out
of luck. You’ll probably not get that to work… Note that
generally, these solders are designed to bond aluminum to aluminum.
Not aluminum to other metals.
Aluminum is generally fastened using so-called "cold bonding"
techniques, like rivits, screws, mechanically formed joints, or the
like. One technique which does actually fuse the metals is fusion
welding, which requires a specific machine. Usually this is used for
things like earring posts or similar findings being attached to the
aluminum. They are made specially for this use, with a tiny “nib” of
metal protruding down from the area which is intended to bond to the
aluminum. The machine places an electric charge between the finding
and the piece to be bonded to, and slams themtogether. As that little
nib just touches the other piece of metal, it causes a spark to jump.
The spark treats that little nib just like a fuse, blowing it. In
essence, it does the same thing as that screwdriver you accidentally
touched a live wire with once. Remember? vaporized half the tip of
the screwdriver when it arced? Will, this is controlled, but that
little “nib” of metal vaporizes just as the two larger surfaces are
brought together. This creates a very hot plasma for just a moment
between the metals, which not only drives off all atmospheric gas,
including oxygen, but also melts the surfaces enough so they can mix
and bond as they contact each other.
Fusion welding is, as I noted, usually used to put earring posts and
other findings on. but it can be used as a more versatile bonding
technique if you consider that a well bonded earring post can also be
considered as a rivet, ready to be inserted through a hole in another
piece of metal, and peened over… Getting any ideas?
The machines, start with the little “sparky” fusion welders sold for
about 400 bucks…
And if you’ve got access to regular electric arc welding equipment,
there are also welding techniques designed for aluminum. Usually they
require some sort of gas shielding of the weld zone, such as with TIG
or MIG welding. Again, this is not normally jewelry scale, but who
Hope this helps.