Hi everyone,
I have a steel reversible ingot mold for making various size round
rod that can be used for sizing stock.
Does anyone have any tips on how to us one of these successfully. I
always seen to get air pockets or the gold only goes part way down
before solidifying.
Thanks, Eric
Heat the mould before you pour your metal, and keep the torch on the
metals as you pour.
Regards Charles A.
Does anyone have any tips on how to us one of these successfully. I always seen to get air pockets or the gold only goes part way down before solidifying.
First, oil the mold surfaces lightly with something such as machine
or motor oil, or coat with a layer of soot, such as from a plain
acetylene flame without oxygen. If using oil, don’t over do it. You
want a thin film of oil, not a wet puddle of the stuff. Wiping the
mold with a rag or brush that’s got a bit of oil on it, just enough
to leave a visibly oiled surface without excess, is ideal.
Then preheat the mold hot enough so that if oiled, the oil starts to
smoke. With soot coating, you don’t get the smoke as an indicator,
but still preheat the mold about the same. Either way, fully preheat
the mold fully, then heat the upper portion of the mold slightly
more, which aids in getting the metal to solidify at the bottom
before it does so at the top. Progressive solidification from bottom
to top is the goal. Not sufficiently or properly preheating your
mold is probably your biggest problem.
Support the mold with a little something, a nail perhaps, under one
end, so the mold is slightly tipped. This helps air escape as the
metal tends to flow down one side.
And make sure your metal is hot enough. If either the mold or the
metal is not hot enough, the metal can freeze before fully filling,
and this can appear as gaps or voids.
Pour in a steady stream, slightly slower than the mold could
actually take the metal. You want the metal to fill from the bottom
up, not all at once. If all at once, you can tend to get voids
running down the center of the ingot. If poured slightly more gently,
that shrinkage void will be mostly confined to the top end of the
ingot.
If you are torch melting the metal, keep the metal fully covered by
the flame during melting, and try to keep both the metal in the
crucible AND the pouring stream also protected by the flame during
pouring. This will help to reduce problems with defects in the metal
due to oxidation, especially with silver or lower karat golds. The
flame used should be at least slightly reducing (soft), and can be
quite reducing, if it will still get the metal hot enough.
By the way, in judging your ingot, if it comes out of the mold
looking totally bright and smooth, without any of the texture of the
mold, you probably did not have something, either the metal or the
mold, hot enough. It’s bright because it’s smoother than the mold
surface on account of it’s solidifying before it could fully form
itself to the surface of the mold. This may still be a usable ingot,
but you’ll get better ingots if the metal can more fully conform to
the mold surface, texture and all.
Hope that helps
Peter
I think that you can get better results by heating the mold to a high
temperature - hard to do if you are torch melting your metal.
Personally, although I was taught to use one of these molds when I
started, I now use either an open sand mold, or the japanese
water-casting method to produce ingots which are hammered, then
rolled, and/or drawn into the appropriate square, round,
D-section…etc.With the steel mold, I always found problems with gas
turbulence, inclusions of flux and irregular top surfaces - all
related to using it at the wrong temperature, I’m sure, but we’re not
set up to prepare the mold in a furnace, so I found it was easier to
switch to a lower-tech alternative.
Jamie Hall
http://primitive.ganoksin.com
Prepare your metal and crucible and flux, a bit more metal than will
fill the mold. I sometimes do a couple of pretend pours. It is more
natural when pouring to turn your hand inwards, so the thumb goes
from the top position towards the oposite hand.
1: oil your mold well
2: heat the mold well till the oil smokes, then some
3: melt your metal also using the flame to keep the mold hot
4: Make sure the metal is spinning after adding a pinch of flux
5: Pour confidently with an unbroken action, dont dump!
David Cruickshank (Australia)
jewellerydavidcruickshank.com.au
Having to lubricate the mould, then heating the mould whilst melting
metal with a single torch is one of the reasons I don’t use a steel
mould anymore.
Delft clay just makes it easier. you can make finer profile ingots,
ready to roll, nice and shiny too. Reset time is faster.
I bought my adjustable steel ingot mould and have used it a few
times, got okay results, if I had bad results it would take a little
while to reset the mould.
Regards Charles A.
Hello Eric,
Check out my blog, Bench of an Apprentice. I have a post where I
talk about using Ingot Mold’s. Here is a direct link:
http://www.ganoksin.com/gnkurl/p3
If the link doesn’t work, just type “Bench of an Apprentice Ingot
Mold” into a search engine.
The mold I used to cast the ingots in this post is from Otto Frei.
A few older books mention “curing” but non include instructions on
how to actually “cure” an ingot mold. Other jewelry makers and books
mention sooting ingot molds but when you don’t have an easy way of
doing this it is a pain, plus it isn’t most healthiest option.
So I decided to take the whole “curing” literally and it works
great!!!
After reading the post you will think I am crazy, until you try
it!!!
If you have any questions do not hesitate to Email me, I would love
to help.
Take Care,
Kenneth, DynastyLab
Hi David,
Pour confidently with an unbroken action, dont dump!
Do you keep the flame on the charge as you pour?
Regards Charles A.
Cant always include everything! Yes I always keep the flame on the
molten metal as I pour. Very important!
David Cruickshank
jewellerydavidcruickshank.com.au
See my ganoksin blog: ‘On Your Metal’
to see my hinged mold which I have found excellent over many years.
Also once I had to make some large 18ct gold nuts so I got some large
cuttlefish and stuck a hexagonal tool into it vertically, cutout a
funnel, heat dried it well and poured the gold into the hex hole.
Excellent. A bit of lathe work and I had several nuts. I have since
used red casting sand, Delft Clay? with excellent results.
David Cruickshank (Australia)
jewellerydavidcruickshank.com.au
Cant always include everything! Yes I always keep the flame on the molten metal as I pour. Very important!
Just asking, thinking that maybe I was doing something wrong, or
could leave out that step.
Thanks David.
Regards Charles A.