Hi all,
I have a coupla spoonsful of gold scrap and filings which I would
like to melt into one lump. Does anyone know an effective way to get
filings to actually fuse rather than just sit in the crucible as tiny
little glowing individual points of light in a groundmass of treacly
flux?
Cheers,
Hans Durstling
Moncton, Canada
Hi Hans,
I’ve had similar problems and have concluded that the problem is the
crucible. If I put all the pieces on a charcoal block and blast
away, they’re a lump in a couple of minutes. I carve out a little
depression in the block so the molten metal doesn’t get blown off the
block by the torch.
I can’t explain it; I’ve read nothing that would support it, but it
has worked for me.
Give it a try!
Linda in MA
Try using an old, well used crucible. Pre heat it so it is good and
hot, put in the filings and sprinkle a good dose of boric acid
crystals on the filings. Heat the CRUCIBLE INDIRECTLY until it gets
hot enough for the gold to melt together. It does help to stir the
filings and boric acid crystals with a graphite or quartz stirring
rod, once the borax is in fluid form (have the rod in a handle of
some sort as the rod will get hot pretty fast, and it does help to
pre heat the rod, either type). The filings will come together and
you can then pour them out. If you are sending the “ingot” out for
refining, be sure to drill a small hole into the ingot, keeping the
drill shavings, just in cast the refiner comes back with a lower
gold content than you calculated, you have the backup ingot sample
for “proof” of content. Good refiners do not take offense of the
"sample hole" as it protects them as much as it does you.
John Dach
Cynthia (my dear wife) is the one who told me this.
30 years ago I watched someone put filings in a piece of paper
towel, put that in a crucible, and set it on fire. More accurately,
torching the bundle till the gold became a molten blob. I don’t
remember, but I assume that at some point they used some borax while
torching. I now believe I was watching an “old world” technique of
reclaiming filing, even with the dirt that accumulates with them. I
believe they used that reclaimed metal to manufacture with.
Richard Hart
A charcoal block with a groove carved into it always works for me.
The charcoal retains and reflects the heat very well and also reduces
the oxygen, allowing me to use as much oxygen in the flame as I need
to get it hot enough to melt. A pinch of borax powder for flux and a
quick stir with a wet chopstick or graphite rod after melted picks up
the worst of the foreign material that might be in it.
Also, I’m using propane, not acetylene, with the largest tip of a
Smith Little Torch or, for larger amounts of metal, the rosebud
(multi orifice) tip.
James S. Duncan, G.G.
James in SoFL
Very simple - just keep going. I use a medicine dropper to soak the
pile with methanol/boric acid first - kind of glues it together some.
It will happen, though. What your message said was that either your
torch isn’t hot enough, or you’re not fusing long enough. It’s takes
a bit to get it all together - nudging with a carbon rod can help,
too. Trust me - if you put enough flame to anything, it will melt.
Don’t forget to run a magnet thru your gold dust to get rid of all
of your metal particles.
Richard,
It is best if the filings are clean before trying to melt them. The
technique I have found that works well for melting the filings is to
wrap them in some tissue paper along with a good amount of powdered
borax. Place the filings in the crucible and soak it with denatured
alcohol. Light the alcohol soaked paper with a match or with your
torch and then melt the filings.
You may need to stir the mixture with a carbon or quartz rod during
the melting process.
Greg DeMark
email: greg@demarkjewelry.com
Website: http://www.demarkjewelry.com
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