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Melting dish


#1

Was: Milling your own or buying stock

Thanks Jay,

Regarding the ingot mold, I'd suggest a combination ingot mold,
one that offers assorted sizes of round ingots, and an adjustable
width of sheet ingots. Super handy and so practical. 

Yes, I am looking at the sort that has reversible plates such that
it will cast round ingot, half round ingot and sheet ingots.

As I’m reading today’s posts, I’ve been looking at the UK suppliers
for these melting dishes John and yourself mentioned but am not sure
what I’m looking for. What are they made of? There are things called
crucibles, salamanders, scorifiers and fletchers!!! One company is
selling a “melting dish” for platinum made of some sort of silica.

Helen
UK


#2
what I'm looking for. What are they made of? There are things called
crucibles, salamanders, scorifiers and fletchers!!! One company is
selling a "melting dish" for platinum made of some sort of silica.

By what you mention, it should serve you well. Platinum simply, by
my reckoning, is tested for higher temperatures than you may need
(much better than the converse).

This is what I use, and used at school (not high backed at school
mind you)

School time (http://www.contenti.com/products/casting/170-710.html)
Now (http://www.contenti.com/products/casting/170-712.html and
http://www.contenti.com/products/casting/170-711H.html)

Don’t forget to prime the “Melting Dish”/“Crucible”… heat with
flame (your torch), sprinkle borax, heat until melted, sprinkle
more, and repeat until there is a good covering of
glassified/liquefied borax over everywhere the molten metal will
touch (including pouring spout).

When using, place clean material (no solder) into the crucible, heat
until molten, continue heating (especially pouring spout, while
pouring into ingot) so as to get a good flow.

Preparing ingot is what I suggest as well. When using oxy/acetylene
I simply have only acetylene only and flash the ingot where the metal
will pour into (the black soot issued will put a light covering that
will act as a resist to aid in removing the poured ingot after it
cools). I use a light oil, set aflame, and put out when using
oxy/propane so as to make a layer of soot for the same reason as
above.

Best of luck and practise makes perfect,
K. David Woolley
Fredericton, NB
Diversiform Metal Art & Jewellery


#3

I’ve been looking at the UK suppliers for these melting dishes John
and yourself mentioned but am not

Hi, Helen. A melting dish is a form of crucible, just of a certain
shape so it has it’s own name. I use big, cheap lineman’s pliers to
pick it up - cheap because they’re getting torched and abused.
Probably it’s not necessary to point out that anything that works is
fine - I’ve used casting crucibles, too. And that the process of
pouring 1/2 ounce is very different from pouring 20 or 50 or 1000
ounces, and the work needs to reflect that. Here in the states
there’s an “Ov-Glove” (or other names) - Kevlar gloves for the
kitchen that fit either hand - very handy. Otto Frei calls these
crucibles on the web site, curiously, but this is the thing:

http://www.ottofrei.com/store/product.php?productid=1440

Or search for melting dish and you’ll see the other kind, which I
don’t like because there’s no lip. BTW, platinum crucibles are a
special bond to handle the heat - some are porcelain. You can also
use them with other metals and some people do. It’s just an unneeded
expense unless you have some reason to like them.

http://www.donivanandmaggiora.com


#4

Hi John,

Thanks again. The platinum crucible I mentioned was made of fused
silica and was actually only 4UKP so not expensive. I’ve had a few
recommendations such as scorifiers (they all seem to have silly
names here in the UK!) which are also inexpensive and made of fused
silica if I remember rightly, so fortunately buying a couple of those
won’t break the bank.

Thanks again for your generous sharing of advice and knowledge.

Helen
UK


#5

hi helen

Harbour Freight Tools has a set of 3 bonded graphite (platinum heat
safe) crucibles, or cuppels ( given that they contain about 72gms.
of metals!) and are straight sided,so tongs would be required. for a
back up set,they are great to have for about 7 US dollars for the
set. If you like I can find the order number…also Contenti has a
wide variety and some on sale at present…(melting dishes only of
fused silica,with no burno style rear pour hole…I like the pour
holes for two reasons:

  1. they allow you to aim quite well the stream of molten metal at
    the mould while keeping the metal covered with an oxide-absorbing
    flame…great bright tough ingots are the result

  2. they are cheap enough ( and its a good practice to keep one for
    each metal used )…and some refineries will accept the metal
    containing slag (Cooksons being one of them!)- simply by enclosing
    the entire used crucible in with your bi-annual or annual refining
    order.and in keeping the metals separated,one can avoid the cost of
    assay!)…anyway…if you’d like more info ( like a flux to use for
    gold casting and reclaimation.) write me off list.

R.E.Rourke