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How to make a good metal ingot?


#1

Hi all, I had some alloy ingot problems,i was used a small
crucible to melt my silver alloy,but my alloy after cooled that
had grey-black colour on the surface(all around),& my crucible
also had purple black colour around,what happen of these & how to
avoid these? some time my alloy was contaminated,and i hope some
one can tell me how to take out the grease? sometime i pour the
alloy to the mold but the alloy was cooled before it going down
into the buttom of the mold,what is the proper way & temp to
heat the ingot mold to ensure the alloy going smooth into the
bottom & dense(a smooth,flat & clean looking ingot) ? do someone
know how to make a clear,dense & good metal ingot ? i will
appriciate if you can give me some advice & share your
experience with me. Thanks

Paul


#2

Paul, I never heat my ingot mold and never have had any
problems.The mold I use is steel I bought it from rio grande
years ago.If you heat your mold too much it could cause it to
warp if it is the two part type.I use a two part ingot mold with
a c-clamp to hold it together.It can make round,1/2 round or bar
shapes depending on how you clamp it together.I keep it in a
cast Iron small skillet this catches any spills and makes it easy
to put back up.I use a round open crucible to melt my metal.it is
held in a steel shaft with a wooden handle.I use a 3 in one oil
which I put a few drops around the oriface the molten metal will
be poured into.This helps the molten metal slide into the mold.I
use a smith torch that I have cut the end of the tip off of. I
can melt all that I need with this about an ounce of gold.Keep
in mind that I am making sizing stock and and small bars for
sheet. I work in gold 95% of the time.This method works for
silver also.I have used open ingot molds to pour pure silver for
silver plating annodes.I used an oxy/acetolyne set up with a rose
bud tip.A rose bud tip is a cylinder as a tip it has many holes
at the end and roars.You can melt large amounts of gold or silver
with it.Smith makes a smaller version that I have never used but
I think it would do pretty good size batches also.Hope this
helps.

Best
J Morley
Coyote Ridge Studio


#3

Hi J, Yes,i had one ingot mold(with C-clamp) which brought from
fdjtool cost around 23 bulk,but only have one part of
design–Flat–,is steel and silver colour look(but not stainless
steel,do stainless steel ideal for ingot),i guess your one is
black colour ,right? Yes,i use a smith little torch & a melting
tip. you say you never heat you ingot mold,but you could made a
good,flat&dense ingot ! Wow,no any smallest holes on the ingot
surface? What your meaning of "3 in one"oil ?what kind of this
oil?

Paul


#4

Paul, My ingot mold is a dark machine type steel.# in one oil is
what would be considered as a light weight oil as opposed to
motor oil wich is heavy any light weight oil will do.No
Holes.Occaisonally I will get a void in the gold bar.That is do
to not pouring in one continuous pour.I find that You need to
pour as one movement and keep the torch on the metal until it
has all poured out.By the way you can use your flat ingot mold to
make square and rectangular stock.You may already be doing this
but take one half of your mold in your left hand and the other in
your right.Now put them together as if you were going to clamp it
together and make a large bar of stock.Look down at the opening
it is a large rectangle.Now slide the half of the ingot mold that
is in your right hand twords you while holding the half that is
in your left hand stationary.The shape will change from a large
rectangle to a smaller and smaller rectangle finally down to a
square.The smaller rectangles are good for making ring shanks the
square shape can be rolled or filed round or cut cross section
wise for shapes. Best J Morley Coyote Ridge Studio


#5

G’day Paul Lee; I use home made moulds which consist of two
pieces of 10 mm thick steel with two ‘blind’ holes drilled down
the length while they were clamped together, so there is half a
hole in each piece of steel. There is a simple register so that
the two halves are exactly opposite each other when clamped. I
melt scrap in an open crucible with an oxy propane torch, with a
soft flame which gives a reducing flame. Then having sprinkled a
little Borax based flux over the melt, I keep the flame on the
crucible and running metal whilst pouring. This gives me two
rods about 6 - 7cms long and about 5mm diameter, which I can
then roll and finally make into wire with draw plates. If I
want a flat ingot I use the same two plates back to back with a
piece of 3mm square steel rod shaped into a U between them. I’ve
used these plates for around 10 years now. Yes, there are the
occasional faulty pours, but it is easy to repeat the exercise.
Yes one does get a few tiny pits in the ingots, but they can be
filed down if necessary and are soon rolled out. Frequent
annealing is necessary when rolling and drawing. Cheers, John
Burgess


#6

Paul, I lubricate my ingot mold with a layer of organic oil like
olive oil As this oil is cooked, it leaves a carbon residue like
a well seasoned cast iron fry pan might have. Another lube that I
especially like, but takes longer to apply is a thick layer of
soot from my torch. These lubes also help to seal the ingot mold
halves. About a hot or cold mold. This can be optional. However.
I have seen accidents many times. The problem is this. There is
a
lot of warm or hot air around a torch head. One of the products
of a torch is CO2. Another is H2O. This water isn’t a problem
around as long as it is strictly atmospheric, but on a cold mold
it will condense. Not much condensed water on an ingot mold is
required to make molten gold spatter when it comes in contact. I
can’t count the number of times that I have been bent over
picking up little beads of gold off of the floor. I have watch
non believers pick up their metal in the same fashion a number of
times as well. A mold that is hotter than 212 degress F will help
one to avoid this pitfall.


#7

hi folks… i use olive oil and put my mold in a kiln to bring
it to temp after i am done with a pour it goes back into the
kiln to reheat…seems to be a much cleaned ingot as the temp
is even i set the kiln at 300 and use gloves … good luck
…ringman


#8

Helps to have good eyesight and greater tweezers… When I bump
my charcoal block and it runs over the edges into my drawer
thanks for the drawer…but getting it up and all together again
is as you know and said…Horrible…time
waster…agravating…etc…etc…calgang


#9

Hi Ringman, 300 temp is C or F ? When i remelt & re-pour my metal
for several time,the metal surface seem become more
dirty(dark-grey colour),what is this happen?how to avoid ?

Paul


#10

As far as the gold spattering, I have seen it happen with a POP
a few times. I have always heated, lubricated with oil and
tipped the ingot mold about 10 degrees. I tip it to prevent the
spattering, I think that if you leave it level and you pour the
molten metal so that air is trapped inside, the air superheats,
expands and blows that metal all over the shop and you. Better
to tip it and pour it down the edge of the openning.

Mark


#11

Hi Paul, I wrote a little web page on making ingots you may want
to look at. It’s at http://www.geocities.com/jwlrymkr/ Ken


#12

Hi All, i have a narrow opening at the top of the mold (i guess
anyone have one also have the same opening),so it made me hard to
pour the metal,i try to use a charcoal block as funnel with i
engrave by myself (open a hole at the central of the
charcoal),but it seem work more good,do someone have more good
idea than this?

My ingot mold height is about 10cm & length is 7cm,i guess that
is too height for the metal to reach to the bottom of the mold
when i pour, is that one of the problem?

Paul


#13

John Burgess, I’m glad that you mentioned the use of a reducing
flame for ingot making. My teacher didn’t mention the fine points
of if, just telling us to make sure the flame was soft and didn’t
hiss. Considering that I have over 15 more years experiance using
an oxyacetylene welding torch than the school’s oxypropane
rosebud I find that I get a much better result using my old Sears
Robuck torch and a number 3 tip. Acetylene has brighter color
contrast and IMHO easier to read even through number 4 welding
glasses or gold didymium glasses than propane without the
glasses. I find that with acetylene if one just turns down the
oxygen until the flame shows a good inch long feather in the
middle but stops before getting significant orange/yellow color
nor smoke silver melts and pours clean.

I use a Rio Grande open ingot mold which is covered with a
crinkle finish stove paint, but the ingots come out just fine. A
problem thought with the oxyacetylene is that if you get the
flame too much reducing (yellow flame means that soot is coming
out) and the silver gets too sooty and then too hot you can get
subsurface carbon inclusions which then form bubbles when it is
rolled then annealed. Nasty little buggers which have to be
burned out with a remelt… Geo