Now showing at the BenchTube (beta)
(Ganoksin answer to YouTube for jewelers.):
Pouring Sheet and Wire Ingots
by Jay Whaley 7:31min
Jay Whaley demonstrates how to use a convertible steel ingot mold,
melting dishes, and a new wire handled ingot pouring tool, to create
sheet and wire stock in sterling silver. An acetylene torch is used
in this demonstration to melt and pour the silver…
Watch Video:
http://www.ganoksin.com/benchtube/video/29/
I’ve been watching some of the videos on the “benchtube posts” and in
viewing Jay Whaley’s piece on casting ingots and sheet, I wondered
why the molten metal does not stick to the sides of the mold. Maybe
fits the “science” thread… but just curious. Thanks
Michael…I was wondering the same thing especially since he did
not include a comment on that aspect of the process. I’ll tell you
how I do it though…simply use my acety torch, cut off most of
the O2 so you have a nice dirty flame and flame both sides of the
inside of the mold with a nice coating of soot. The ingot just about
falls out.
Cheers from Don in SOFL.
Two reasons gold and silver won’t adhere to the moulds when melting -
although not shown in the video, when I did my apprenticeship we
lightly smeared the moulds with oil before putting together and the
mould is warmed to take the chill off but not heated too much (this
prevents the metal from spitting through a thermal shock) and the
molten metal will solidify fairly quickly.
Roger
Hello,
well, I do it the same way. A nice coat with teh soot and this works
fine. A second advantage is that the soot (carbon) absorbs oxygen
creating an reducing atmosphere. Some people like to use candlelight
which does the same. Others like to use a very thin layer of oil but
I don’t like this way due to the smoke and smell of the burning oil.
Best regards
Pedro
It doesn’t stick for the same reason that solder doesn’t flow into a
cold joint - the metal freezes on contact with the mold and never
"wets" it. No wetting = no joint; and the lack of flux plays a part
too. I was rather disappointed with the video - the commentary was
drowned by the noise of the torch, the closeup of the melt was
obscured by the mold itself, and was out of focus.
Regards, Gary Wooding
Don, Michael and others,
As far as preventing molten metal from sticking to a steel ingot
mold, there are a few different ways to do it, and probably more.
Sooting it with an air-starved acetylene flame does a good job, but a
very light coating of any kind of oil works nicely, too.
If a coating of oil is used, make sure that it is wiped almost
completely out of the ingot mold’s interior, however. Only the
thinnest amount of oil is required to prevent sticking of the ingot.
It is vital that some air be able to escape from the two halves of
the metal mold when the liquid metal is poured into it, and an excess
of oil can hinder that air flow. Too much oil can not only keep the
ingot mold from filling completely, but may actually cause a "burp"
when the ingot is poured. Hot metal contacting oil can force the
metal back out of the ingot mold, sometimes quite forcefully…not a
good thing.
I think of ingot molds like a seasoned iron skillet. After continued
use, the ingot mold just seems to resist metal sticking to it. When
ingots eventually become difficult to remove from the mold, then I
will either soot or oil very lightly oil my ingot molds. Most of my
poured ingots pop loose from the mold with just a light tap on the
top of the ingot with the mold clamp. Be sure to warm the ingot mold
with a torch flame before pouring hot metal into it, as cold steel
at room temperature has a certain amount of atmospheric moisture in
it. Heat will drive off any moisture which can cause a big problem
with steam during the pour. Any possible moisture in an ingot mold is
to be avoided, absolutely.
Jay Whaley
Orchideans,
I was wondering the same thing especially since he did not include a comment on that aspect of the process. I'll tell you how I do it though.....simply use my acety torch, cut off most of the O2 so you have a nice dirty flame and flame both sides of the inside of the mold with a nice coating of soot. The ingot just about falls out.
To those of you who pour your own wire ingots:
You are probably aware of this phenomenon of physics when you pour a
wire ingot a little too full. When pouring into a round wire ingot
hole, it is tricky to stop the flow of metal into the mold until you
see the metal forming a “button” on top of the mold. Too much metal
poured and it runs down the sides of the mold, sometimes causing
problems getting the mold open. (Sound familiar??) When that
“overflow button” forms on top of your wire ingot, do you ever notice
that often that button has cracked itself off from the wire ingot as
you are removing it from the mold? You were going to have to cut that
button off anyway, but it mysteriously fell off by itself! As the
thinner wire ingot cooled after being poured, it contracted, and
pulled itself away from the still hardening “overflow button”.
Science in action!!
Jay Whaley
The “sooting” of the mold is not a frequent need, in my 5 years at
UCDS’s Jewelry Studio, I have seen Jay do it twice, and then not in
the same year.
Those molds get a lot of use, by brand new students, as well as we
long timers. The work flawlessly, every time. I know warming the
ingot mold just prior to melting and pouring the molten metal adds
to the ease of the process.
Coming Soon, watch for “The W.H.I.P.” this will be another short
video clip by Jay Whaley.
Hugs,
Terrie
the reason for pre heating of the mold is to eliminate moisture from
condensation. If you look at the steel mold when you start to heat it
you will see moisture on it. When the molten metal hits this moisture
it can cause the metal to splatter. Very light oiling of the molds
work fine and as the mold gets “seasoned” like a cast iron skillet,
you can you can oil much less often.
I have always taught people to use ingot molds a little differently
than the video demonstration shows. Typically we are using it to
pour a square rod to roll into a shank, sizing stock or wire. So we
have the flat side set to a small square. I ask that people prop up
one side of the ingot mold on a pair of tweezers, so the mold base is
raised on one side. I do that because of an accident we had in the
shop years ago, a goldsmith was pouring some gold into a warm ingot
mold at her bench, there was a loud POP and the glob of molten metal
flew through the air and landed on her shoulder. She went to
hospital with terrible burns. What happened (I believe) was that the
molten metal covered the opening of the hole, super heated the moist
air inside (was a humid day), it expanded rapidly and forced the
molten metal back out like a volcano. It wasn’t the first such POP in
the shop.
So our whole procedure is that we prop up the ingot mold, heat up the
mold so it’s just too warm to touch, put a bit of wax around to top
of the hole (not vital but helps prevent sticking), melt the metal in
the crucible, hit it with a dash of casting flux (helps the molten
glob to hang together without leaving little bits about the crucible,
also helps any crud float to the top center of the glob for easy
removal with a stirring rod), pour the molten metal into the ingot
mold (never lifting the torch until poured) while aiming for the
inside edge of the hole (remember the volcano story). Works like a
charm.
Mark