Hi there,
I have a reversible ingot mould. I use it in my jewellery class. To
start with everyone used it with sucess but now when we pour into the
bar/wire section we never have a successful pour. I have tried
cleaning it but it doesn’t work. Anyone know what the problem could
be?
Thanks,
Helen.
Anyone know what the problem could be?
Did you oil it, lubricate it, or blast it with soot before you
poured your metal? CIA
Helen- Do you oil it first and then heat it up first before pouring
the ingot? You may have cleaned it too much. Like scouring a seasoned
cast iron frying pan with soap and water.
Have fun and make lots of jewelry.
Jo Haemer
timothywgreen.com
Hello,
Have you tried using a wire brush to remove previous coating or
excess and recoat with an oil and cure or heat in oven at 350*F for
an hour.
Hope this helps.
Hi Helen
Not sure why you are having trouble doing wire ingots. First, I put
a layer of black soot on the mold, using the acetylene torch and
cutting off the air holes so that you get pure acetylene soot coming
out of torch. When you get a nice even layer of black soot which
will look like black velvet, clamp together the molds. Get your
silver or metal nice and hot, so that it is liquid in the crucible.
Make sure you keep your torch on the molten metal at all times, even
when pouring. Carefully position crucible, sprout side facing the
mold, and pour steady - not too fast but not too slow. The biggest
holes will the easiest to pour molten metal into, the smallest is
the hardest and avoid if possible. If all fails, upgrade to an ingot
bar mold, which is larger and open on top. Sometimes when I have a
temperamental batch of silver that will not pour into the ingot
mold, I’ll use the ingot bar mold. Use a little borax on the silver
when melting (some of you Orchid members will beg to differ, but
that’s what I have on hand and use).
Let the metal cool for a minute or two and then release them from
the molds. Hope that helps. I do it routinely now. The trick for me
is tokeep the torch on the molten metals at all times, and esp.
during the pour so that it pours out evenly. Most people melt the
metal, turn off torch and pour and then they don’t get a good pour
for the metal is solidifying already. The hotter the torch, the
better. Also, the smaller, lighter “Whip” crucible from Rio Grande
seems to work better - less ceramic mass, lighter and easier to use.
Joy
I use these too. The main things to keep in mind are :
1 Warming the cleaned mould thoroughly before the pour- make sure
there aren’t any small bits of gold around the base where the plates
join, or on the convex swages where the metal will go when poured.
Just a little carbon, gold,and grease can spread along the edge
causing a number of problems if you intended to yield a perfect rod,
but they’re nothing that further forging or drawing won’t eliminate
unless there was a lot of "gunk’ that wasn’t removed, or someone
accidentally used the mould for a metal other than whatever it was
dedicated to (gold for instance was what the mould was dedicated to,
and someone decided to melt nickel then used it, and stored it
without cleaning first).
2 Use the torch and lay in some blackening, if you’ve tried beeswax
and it didn’t work well. Sometimes the lampblack gives a coating
similar to what graphite would do. since there are many factors
involved like what kind of metals (clean casting grain, scrap,
raising or lowering the karat and any de-oxidants you may add) are in
the crucible and the torch work technique of one person compared to
another in using a relatively small mould all make a difference, if
blackening doesn’t work, try a bit of beeswax before warming- one or
the other should give you a complete rod or bar…
3 I always use a refining flux when melting - sal ammoniac and
pulverised/ powdered charcoal (1:4, store in an airtight container,
preferably non-metallic, as sal ammoniac is an humectant and will
absorb humidity from ambient air). It will give you a bright tough
ingot particularly with gold scrap included in the melt.
4 Make sure the mould is tightly secured plate -to-plate, no matter
which side you are using. On some moulds the plate for sheet/ingot
has a 'stop", it doesn’t line up perfectly, so you have to move it
over a bit to get good edge to edge contact. As long as it’s clamped
down as tightly as you can physically get it you shouldn’t get any
leaks, etc.
5 Using a well glazed crucible (’ Burno’ style with a hole in back)
well fixed in the tongs with the hole cleared to the extent possible
leaving a fresh coating of borax helps as long as you keep the torch
heating both mould and crucible pouring point warmed (the crucible
will be red hot and the mould may still be smoking the lubricant
-indicates that both parts are ready to accept the molten metal) and
the crucible is as close as possible to the mould without it being
directly on it or covering the mould inlet at all. you don’t want the
metal to have a further distance through air than to mould…
hope this is a good check for you, and you’ve already eliminated
these obvious points. Good luck. rer