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Overlay problem needing your advice


#1

I’ve lurked for a while but this is my first post…so hi everyone.
I’m an aspiring jeweler way down here in Texas. I decided to give
overlay a try on some pendants which are circular or rectangular in
varying sizes but nothing over 1 1/2" square. Everything was going
great. Pre-flowed the solder on the back of the top pieces. Cleaned
the bottom pieces really well. After soldering the top to the bottoms
on a couple of pieces I realized that for my design (areas of thin
scrollwork) I’d used too much solder and that brought a LOT of clean
up with it when the pierced/sawed areas filled with solder. So I
looked at the others and filed/sanded the solder down to get it more
level and remove areas that I knew would flow into the open
scrollwork filling them with solder.

I soldered the remaining pendants on which I’d thinned the
pre-flowed solder. They all soldered but not completely. In some
areas there is a thin line of solder with gaps at the edges. In
other areas, it looks like the solder didn’t flow at all. Some of
the areas are small but others are much larger. Sort of hit or miss.

The set up I used was a tripod with mesh screen. I heated the
pendants from underneath and every now and then on top to get them
to the same temp. I applied pressure when I thought an area needed
it. At times, I felt I almost fused the metal due to the high
heat…but that didn’t happen.

Here are my questions:

  1. Is this because of removing too much solder in the filing/sanding?
    I felt there was a good layer of solder still there for the area.

  2. Is this because of not heating long enough? I felt I almost
    overheated.

  3. Taking the pieces apart is not an option. I’m not sure adding
    more solder is an option either due to the designs. Is there
    something else I can do to save these pieces…they are part of a
    show in December. I have cleaned the joints thoroughly after
    pickling and neutralizing…I put them through the ultrasonic and
    the steam cleaner.

Just thinking I need better, more experienced heads than mine on
this problem.

Many many thanks!


#2
Is this because of not heating long enough? I felt I almost
overheated. 

Well, Karen and all… Overlay soldering has it’s own challenges. I
have found one simple, easy solution to it that removes many problems
in one swell foop - paste solder is much maligned for many uses, but
it was made for overlay soldering. Just smear it on the top part with
your finger, put your parts together and solder from below, as you’ve
said, on a tripod. Just exactly the right amount of solder spread
just exactly evenly across the join. Poof! Easy!


#3

Hi Karen. I’d suggest a couple of things. After you initially thin
the solder on the back, sand it down well to even up the layer of
solder so you can get a closer fit. Make sure you flux both sides
before assembling. I like to wire a piece together AND attach a
series of clips around the perimeter to put pressure on the edges-
and then put more flux around the edges too.

I also like to use two torches, so you can hit both top and bottom at
once. However, I’m doing bigger pieces, often with 4 layers getting
soldered together in one pass. And always be ready with a pick or
tweezers to give a section a little extra pressure as the solder
flows- watch closely. Good luck!

Allan
silvermason.com


#4

I love the Orchid world. I was able to solve the problem following
many of your suggestions. Flattening the pieces further, bringing the
piece up to temp more quickly (which was the principal problem as it
turns out), using paste… these worked and I was able to complete
the soldering. Still some clean-up to do on some of the scrollwork
which someonetold me was a sign of having overheated. Gonna get the
hang of this yet!

Many thanks to you all!
Karen


#5

Hi Allan, What kind of clips do you use? I’ve tried some before but
had them fuse a little to the piece. Fortunately I save it but have
avoided clips since. The clips I used were cotter pins but I don’t
recall the metal they were made of.

All the best,
karen


#6
Hi Allan, What kind of clips do you use? 

I’m not Allan, but I make tiny “cotter pins” out of titanium sheet,
which cannot be soldered to your piece. But then, I have titanium
around.

Noel


#7

I learned to make clips out of wire hangers. They are hard to forge,
but strong, and hold up well to soldering. Blacken them with a good
amount of heat to help prevent solder sticking.

Lisa Weber


#8

Karen,

I’ve been doing overlay work since the early 70’s, and it’s not that
hard to do. I’m no fan of pre-soldering the top or bottom sheet being
soldered together, and haven’t liked working with paste solders. Way
too messy. Usually, the bottom sheet of a traditional overlay has
some kind of texture applied to it, and with intricate piercing,
nearly impossible to texture evenly that recessed background after
soldering. So texture the background with a diamond bur, a Florentine
liner, or something before soldering, would be my suggestion.

My biggest concern is that the two sheets to be soldered together,
the pierced top sheet and the bottom plate, are absolutely flat
together before soldering, or even fluxing. I flux the two sheets
while they are flat together. I always make sure there is an excess
of back sheet around the outside of the overlay being soldered, as a
"shelf" for the solder pieces I place there. After soldering, this
lip is sawn off and filed smooth.

After I flux, I will carefully warm the overlay to be soldered to
dry out the moisture in the flux. If you don’t do this pre-warming
step, your solder pieces will fly all over the place as steam
develops during heating.

I always solder with a bushy flame, working underneath the overlay.
Use a heavy stainless steel screen on a tripod, as an example. I like
a Prestolite acetylene torch for this purpose, not a torch with a hot
pointed flame.

If you heat in an even, circular manner, and your solder chips are
placed around the outside of your overlay, touching the edge of the
top sheet, you should have terrific flow into the interior of your
pierced top sheet, with no solder puddles on the visible back sheet.
You may need to do several solderings to get everything completely
soldered. Use a medium solder, if you are soldering silver, as hard
solder just requires too much heat to flow in the manner needed. Oh,
and if you are soldering silver, a fabulous heat conducting metal,
turn up the heat! You’ll need plenty.

I also am not a fan of using clips or cross-locking tweezers to hold
overlay-type soldering together. In my experience, the clips are
huge heat sinks, and because the metal can soften when hot, they are
apt to leave marks in the surface of the metal being soldered.

Hope this helps!

Jay Whaley