Am I using the wrong flux or techniques?
Hi Michael. Wrong techniques! What you're doing will work for
silver which is a great conductor of heat, but not for gold which
isn't. With a larger gold bezel, trying to heat the whole piece
evenly is usually counter-productive -- especially with such thick
base metal (I use 14K 28 or 26 gauge backing with 22K bezel wire).
By the time you've moved the torch from one side of the bezel to the
other, the metal is already cooling off on the first side.
So, I'd consider using thinner gauge backing metal; it's not quite
as difficult to get hot (and not so expensive either!). Did you say
50-70 mm?!? Wow, that's big! Still, 24 gauge (certainly 22) might
work without warping too badly. Next, I'd get rid of the heavy
screen which is acting as a heat sink and making it even harder to
keep the gold hot.
Here's what I'd suggest: Put the piece on a charcoal or "magnesia"
block; both absorb heat and will assist in getting the metal up to
temperature. Warm up the entire piece somewhat and then focus on
trying to tack the bezel down at, say, four opposing points. Don't
worry about flowing the solder yet; what you want to do is stabilize
the bezel so it won't move.
Once the bezel is tacked down, do one of two things. 1) Put the
piece in a third hand so it's suspended. You'll need to find
something to prop up the third hand's tweezers so the assembly won't
move. 2) (Assuming you're right handed) hold the piece in tweezers
with your left hand and keep the torch in your right. It's okay to
have one blade of the tweezers on top of the bezel and the other
under the sheet; just be sure not to squeeze too tightly! A
cross-lock tweezers is usually okay. A self-locking tweezers will be
Note: If you pre-placed all your solder chips (I do it inside the
bezel) and fluxed sufficiently (I prefer Cupronil but there's
nothing wrong with Batterns) and didn't overheat the piece and
you don't let the piece cool off too much while you're repositioning
it, you should be able to keep soldering without refluxing.
If the metal has cooled off, you'll have to reflux. If you didn't
use enough flux in the first place or overheated to the point that
the solder joints have developed scale, you'll need to pickle to
clean the metal, reflux and replace your solder chips before
Now, with the piece suspended, you can reheat from the bottom (less
chance of melting the bezel and better chance of keeping the heat
focused). Flow the solder between two of the tacked points, then the
next section, etc., until it's done. You will probably have to
reposition the piece at least once so you're able to solder the side
that the tweezers were on in the first place.
Note: You could not in most cases do this with silver. If you
suspended a large piece of silver this way by a corner and then
heated from below, by the time you got the whole piece of silver hot
enough for the solder to flow, the sheet will have slumped. Since
you can "spot solder" gold, without needing to heat the whole piece,
you can avoid this problem if you're careful.
I'm sure you'll get other suggestions and you'll want to experiment
to see which works best for you. There isn't just one right way.