I have been experimenting with adding gold (22K) and silver
(sterling) to old metal mostly old handmade square nails. I’m trying
to get the gold and silver to fuse and flow over the steel. I have
cleaned the rust with a wire brush and flux with silver-gold flux.It
seems to be very random as mostly the metal balls up and won’t
adhere. I have tried solder and using powdered silver as well as
snipits. sometimes it flows, sometimes it balls and adheres
andsometimes nothing. Is there a way to increase chances of bonding?
You likely need to do more than wire brushing. Unless you are looking
at bright metal there is still is a heavy layer of iron oxide. Iron
is very active with oxygen so you need a good active flux to protect
it during soldering, I use Handy Flux or Handy Flux B-1 to protect
during soldering to steel. You also need to work fast to limit the
oxidation problems.
I have been experimenting with adding gold (22K) and silver
(sterling) to old metal mostly old handmade square nails. I'm
trying to get the gold and silver to fuse and flow over the steel.
I have cleaned the rust with a wire brush and flux with silver-gold
flux.
For silver and gold I too use a flux specifically formulated for
precious metals, but it doesn’t work very well for base metals. For
consistent results with base metals such as brass or ferrous metals
(iron, steel, stainless steel) I use either EasyFlo or Tenacity; both
made by Johnson Matthey. EasyFlo works well for almost everything
that’s solderable, but some stainless steels need Tenacity. Because
I’m not keen on using Tenacity (it’s very difficult to remove the
residues, unlike EasyFlo which dissolves in hot water) I always try
EasyFlo first, and switch to Tenacity only if necessary.
You could damascene the nails with gold or silver foils. It’d give
you the gold look, without having to heat anything up. (you use
chisels to shred the surface of the iron into metal velcro, and then
use wooden punches to drive gold foil down into the shredded
surface.) Looks like fine gold linen fabric when it’s done right.
I did a ‘how-to’ paper on it in the SNAG news a couple of years ago.
Probably findable via google. (2007). If you don’t have any luck,
email me, and I can send you the PDF.
Have you considered cold connection such as rivets or srews? If it is
an option on your piece, this would solve your soldering problems
and might even look cleaner.
In the 80’s I have soldered some gold to steel and did not have a
problem with it so I must have been lucky with the kind of alloy
used in this specific steel. Have you been using different steels? I
am not a metallurgist but if it is the case, could it be that the
all oys in these different steels make a difference?
For consistent results with base metals such as brass or ferrous
metals (iron, steel, stainless steel) I use either EasyFlo or
Tenacity;
I’ve done this sort of work a few times - certainly no expert. But
here’s another tip that can help, but it depends on what results you
need in the end. If you’re soldering a single gold ball onto steel,
this is not useful.
Otherwise, “Tin” the steel first. Clean, use whatever flux works, put
the solder down but not your design, and use some tool to drag the
solder all over the steel, and scrub it as needed, until the surface
is covered - really covered means the solder won’t “break” when you
get it molten, showing steel underneath. Once you do that, the steel
is shielded from the atmosphere, and the rest is relatively easy.
Usually I’ll cool it, clean it, push fresh flux and THEN do the
soldering. Again, it’s not a method for every job, just
some.
Clean the steel well use Black paste Flux (from welder supply) and
easy silver solder not gold solder.
Solder must melt before the steel oxidize - don’t remove the heat
till you see the solder flow or you have to start over. Let cool soak
in warm water to clean flux off.
Some things to think about, good solder joints rely on the solder
throughly wetting the surfaces of the metals being bonded. The
greatest contribution to the wetting ability of a solder is the
surface tension of the molten metals in the solder on the solid
surfaces of the metals being soldered. Silver does not wet iron
(steel) very well. This means that a molten blob of silver on a
clean oxide free steel surface will stay drawn up into a bead like
water on a waxed surface. Copper wets iron better than silver, gold
is quite good and zinc is even better at wetting iron. So gold
solders will do a better job of wetting or spreading on the iron than
silver solders, low melting point silver solders which are high in
zinc will wet or flow better than high melting point silver solders
with less zinc in them.
Freedom from oxides and dirt also contribute to wetting and when
torch soldering a good flux will keep a properly prepared surface
clean and active long enough for the solder to flow but if the basic
wetting property is not there then it will be quite difficult if not
impossible to get a good joint.