The mold I've found in one of the online retailers can be used for
either wire or flat to make sheet metal.
i assume you’re talking about one of the reversable sliding molds,
with two plates. Assembled with the flat sides facing in, one can
pour varying widths of flat ingots for sheet metal, while when
assembled with the vertical holes lined up, you pour round rods to
roll and draw into wire. This type of ingot most is usually the most
versatile, and is usually the right choice, especially for a beginner
at this.
But as I've discovered with most other items purchased in this
learning process, nothing comes with instructions! Sheesh! Ladders
come with instructions these days!
Ladders come with instructions because it’s assumed everyone buying
one is an idiot who will fall off and then sue the manufacturer.
Ingot molds by contrast, are likely considered professional tools and
it’s assumed that those buying them would have some idea how to use
them. Besides, if you mess up, it’s not likely that the mold itself
will do lawsuit worthy damage…
Ok, now that I've vented, does anyone know if an ingot mold be
used by pouring molten metal into it as done with salt casting?
No idea how you’re doing salt casting, but ingot molds are used by
melting the metal in a pouring crucible and pouring it into the mold.
So that’s likely pretty much what you’re doing with the salt…
Does it need to be coated with flux or some other materal to be
able to remove the silver ingot?
Usually, yes. There are a few options. Easiest is a light coating of
oil. Ordinary automobile oil, light machine oil, or the like. Just
enough to the surface is lightly oiled, not dripping. The other
common choice is carbon, or soot. You’d do that with the flame from a
torch without air or oxygen, so it’s a bright yellow flame. Hold the
ingot mold above it until it’s uniformaly coated with black soot.
Over time, you’ll likely use both methods from time to time, so
eventually the mold will be covered with a mix of soot and burned
oil…
You use flux to melt the metal, but you do not flux the mold. Doing
that might allow the molten metal to actually “wet” the iron mold,
which would not be good. In essence, that would be soldering your
ingot to the mold. Not what you want at all.
Does it need to be used with a spout/funnel?
No, the molds have flared ends to the round holes and the flat sides
too. You’re supposed to have good enough hand eye coordination to be
able to pour the molten metal into those holes directly. With the
glare of melting metal, this can indeed sometimes be a bit of a
challenge, even for those of us with experience. But if you miss, and
not all the metal goes where you want, just put it back in the
crucible, remelt, and try again. You’ll have to do this from time to
time when the ingot doesn’t come out good enough. No big deal.
By the way, there’s a bit more to this than merely coating the mold.
If pouring round rods, be sure the mold is lined up accurately, so
the rods come out without excessive fins or displacement at the mold
line. Also, be sure, with either wire ingots or sheet, that the
movable side of the mold is firmly all the way down onto the base.
Sometimes, when tightening the clamp, you can slightly lift up the
bottom of that plate, and then the metal can run out the bottom.
When your mold is set up right, set it on a suitable fire proof
surface large enough so if you spill, the metal is not lost or on the
floor or something. Then, put a nail or a bit of something under one
end of the base, so the mold is very slightly tipped. This helps the
metal flow in without trapping air, especially when pouring rods
instead of flat ingots.
Now preheat the mold. This is critical. If you pour molten metal
into a cold mold, there will likely be a bit of condensation (just
from the combustion products of the torch flame if not already there)
in the mold, and when metal hits that moisture, it can literally
explode back out of the mold. Nasty and dangerous. So preheat the
mold. This is where using oil to coat the mold is handy. You can heat
the mold until the oil is smoking (even after you pull the flame
away). That’s a nice indicator of when the mold is hot enough. It
will be a lot hotter than you’d want to touch, so be sure it’s
properly located before you preheat. And you’ll want a pair of pliers
or two to handle the mold and clamp screw after pouring, since it
will still be too hot to touch.
With the mold hot and slightly smoking, melt your metal, with a bit
of flux and a slightly reducing flame, and when it’s nicely liquid,
pour it into the mold. Try for an even uninterrupted stream of metal.
Not a halting uncertain pour nor a sudden dump-it-all-in one either.
Especially when pouring silver, as you pour, keep the torch flame on
the metal and try to have the flame extend over the top of the mold,
so the pouring metal stays within the reducing atmosphere of your
flame. This can be tricky, but try, at any rate.
You may find, by the way, that with silver, getting good sheet metal
is a lot harder than getting good wire. The reason is that silver
tends to absorb oxygen and gasses when molten, and gets rid of it as
it cools. That leads to small bubbles in the solid metal. When you
roll an ingot with these out into sheet, they spread out into blister
shapes, and when you anneal, the puff up,messing up your sheet metal
(it was already messed up with the blister cavities, but you don’t
know it till it puffs up…) With wire, however, any such little
bubbles get rolled down to a long thin threadlike shape pretty much
down the center of the wire. Sometimes it will form a defect in the
surface, but usually that’s a small portion of the wire, more easily
avoided than a defect in the middle of a piece of sheet metal.
Anyway, if it’s a long threadlike inclusion in the wire, then the
smaller you draw the wire, the smaller that defect becomes too,
instead of spreading to a wider and wider blister as it does in sheet
metal. With wire, it just gets longer, along with the wire, but
doesn’t otherwise get in the way of normal use of the wire. As I
said, you may now and then find defects in wire you make, but usually
most of it will be usable.
For me, I make my own sheet and wire when working with platinum or
gold. But with silver, I buy commercially made sheet metal and use my
scraps only for wire, or for casting.
I am a member of FSGNE; I've asked one of the members, but she
doesn't know if the group has a "guild" owned one or not. I am
also assuming that you wouldn't want to mix metals in them, right?
If you use an ingot mold to melt metal in directly, the mold will
become hot enough the metal will wet and adhere to the mold. That
will destroy both your ingot mold and the metal (which then will have
some iron in it as a contaminant). You use the molds hot, but not
THAT hot. Usually they’ll be somewhere around 300 - 400 degrees F or
so at the most, and covered with a carbonized layer of oil and/or
soot, so the metal doesn’t stick. If you melted the metal in them
directly, you’d defeat that protection.
By the way, if you find this too frustrating, remember that your
scrap is almost as valuable as new metal. You can send the scraps to
any decent refiner in trade for new metal. They take a percentage of
course, but if you weight the value of your time, you may find it’s
more efficient to buy your metal already as sheet and wire, sending
scrap in trade. This is more likely to be the case with beginners,
who may end up spending an inordinate amount of time trying to get
good ingots. I’m not trying to dissuade you, of course, just
remember you have the option.
Hope that helps
Peter Rowe
