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Seeking Advice on Soldering Gold


#1

Orchidians: I could use a little advice on soldering gold. I have
worked with silver for a few years and am now trying to learn to work
with 18Kt and 22Kt yellow gold. Unfortunately, most of my attampts to
solder end up melting the gold instead.

For example, after I used my hydraulic press on an annealed sheet of
30 gauge, 18Kt yellow gold, I noticed some cracks. I annealed the
metal and worked the cracks closed. Then I fluxed the sheet, set a
few pallions of 18Kt medium solder on to the cracks. I put a No. 4 tip
in my Little Torch. I set the Acet/Oxy mix to a neutral flame. But
despite my best fforts to use a light touch with the flame, the gold
sheet turned red and melted. The solder never ran. Can anyone give me
a few pointers as to what I’m doing wrong? Thanks.

Michael Conlin


#2

Hi Micheal, 30g sheet is so thin (it is what I use for bezels) that
it can be really tricky heating it up enough and not melting it. Your
press may have stretched the sheet even a little thinner. You might
want to try the easy solder for such thin sheet although you may have
some of that color difference show up. One suggestion I can offer is
to pre-melt your pallions. I melt my little pallion squares into
balls and then place them where they need to be. For some reason they
flow more easily than if I just place them directly on as squares.
Besides that, have the piece super clean and fluxed and cross your
fingers. With my bezels I have found that I need to get that solder
to flow as quickly as possible and not linger heating the metal. If
it is not flowing pretty quickly and I keep heating then the edges
of my bezel start to melt away in a very unattractive way. But
pre-melting the pallions has really helped me. -Carrie Nunes


#3

Michael, one of the problems in moving from Silver to Gold is the
thermal characteristics of the metals. Silver is a much better
conductor of heat compared to gold. It wants to be the same
temperature all over, where gold is quite happy to have hot spots
and cold areas. As a result, the gold solder doesn’t flow like the
silver solder does. With silver, the whole piece is near the flow
point of the solder, and the point of the torch pushes the
temperature up just enough so that the solder flows to the heat.
This lets you walk the solder around a path, just using the torch.

When you try this with gold, it doesn’t work well. The gold doesn’t
conduct heat as well as silver so the surrounding areas are not
nearly as hot at the point of contact with the torch. As soon as you
move the torch, the metal cools and the solder quits flowing. If
you try to bring the whole piece up to temperature as you do with
silver, you get the melt-downs you describe. This has driven me
nuts over the years making bezels for opals. I have found that
using a solder pick to drag the solder along the seam seems to help,
rather than waiting for it to follow the torch. You still might
have a gap now and then, but you can re-solder them.

Don at Campbell Gemstones