Back to Ganoksin | FAQ | Contact

Plaster of Paris for soldering


#1

I am making a cuff which I intend to encrust with jewels. I realize I
need to shape it prior to soldering on the bezels. To keep its shape
during the soldering, I was thinking of making a plaster mold of the
internal for it to sit on during soldering. Do you think this will
work? Any other suggestions?

Yvonne


#2
I am making a cuff which I intend to encrust with jewels. I
realize I need to shape it prior to soldering on the bezels. To
keep its shape during the soldering, I was thinking of making a
plaster mold of the internal for it to sit on during soldering. Do
you think this will work? Any other suggestions? 

A plaster mold of the inside is going to cause no end of grief.
Solder it in air and air cool as many times as required. If it warps
my favourite tool is a hammer, and maybe a planishing punch on a
steel mandrel.

jeffD
Demand Designs
Analog/Digital Modelling & Goldsmithing
http://www.gmavt.net/~jdemand


#3

Yvonne, This in a very old trick. I learned it from my Chinese
teacher in Taiwan nearly 40 years ago. I don’t use it often but it
really does work.

Cheers from Don in SOFL.


#4

I would use investment rather than plaster of paris, just to be sure
it can take the high temperatures. No matter what you use, make sure
it’s one hundred percent bone dry. Like cured in an oven set to
around 250 degrees Fahrenheit for about an hour dry. Quickly heating
materials that have moisture trapped inside them can lead to
unpleasant surprises of the explodey variety.

If the plaster is a little wet it’ll probably just crack or pop off
harmlessly… But probably isn’t a word I’d like to bet on when
getting hit in the eye with something hot and pointy lies on the
other side.

I’m not entirely sure why you want the plaster inside the bracelet
though. Whenever I’ve heard of people soldering something embedded
in investment it was usually to put together several small parts,
like making a wire basket setting. As long as the bracelet is fully
annealed before soldering I don’t think it ought to flex beyond what
a few light raps with a rawhide mallet over a mandrel would
straighten out.

Willis


#5

It might be better to use investment if available since it can
handle heat beter.


#6

I believe because you will still have heat expansion there will be
some issues. You could try the plaster but it becomes a heat sink
and will require more heat to solder on the bezels. Use an extra easy
solder with the plaster and wire wrap the cuff onto the plaster to
keep it in place. See if that will help you.


#7
I am making a cuff which I intend to encrust with jewels.[snip] To
keep its shape during the soldering, I was thinking of making a
plaster mold of the internal for it to sit on during soldering. Do
you think this will work? Any other suggestions? 

I would carve a “bracelet mandrel” out of a soft fire brick. Seems
easier, and it will be around the next time you need it.

Noel


#8

Yvonne,

Filling the cuff bracelet with plaster isn’t the best idea, I am
thinking. Casting investment would be the better choice, as it will
hold up to the soldering temperatures you’ll create, but I still
don’t think this is a good idea. That chunk of investment inside the
bracelet is a big, nasty heat sink, which will make it SO much harder
to get your bracelet and bezels up to soldering temperature.

You might also find that heating inside the cuff, beneath the bezels,
might be the better method of soldering the bezels to the cuff.

Good luck!
Jay Whaley
www.whaleyworkshops.com


#9

Jeff- One of my favorite “old Indian tricks”.

Place your ring or bracelet or whatever curved surface you have on a
mandrel.

Melt a very little sticky wax on the top of the ring or bracelet.
Place your crowns in the wax. Then make a dam out of plasticine
around the top and pour in investment plaster. Let it set. Then
remove the plasticine from plaster lump.

Turn it over and lightly steam between the crowns to remove the wax.
Flux and solder away with high carat solder. Dissolve the plaster and
solder the curved unit to your bracelet or ring with a lower temp
solder.

Makes a perfect fit every time.
Have fun and make lots of jewelry.
Jo Haemer
www.timothywgreen.com


#10

Yvonne,

why mess with something you don’t need? Don’t bother going to
"Paris" or “dental school”… go old school- tie wire.

Now, there’s an old saying that sounds appropriate here; it goes
like this: “you can do a lot just by trying”.

From the clues in your short, post, I'd say you were working in
silver; I'll assume that is correct. 

So here ya go, try this recipe.

Make your workpiece using a suitable gage material, such as 16 ga. It
will last, have a good hefty feel, yet be formable enough. It wont
"relax" and flatten out as you solder it.

Use suitable sized iron wire to hold your bezel(s) down. Don’t use
iron wire so big that it will crush the bezels.

Warm up the piece, then coat the whole thing with your fav flav of
flux / firescale inhibitor. (. lots of surface area for the nasty
firescale to show up in if you don’t prevent it).

Then place, prop up, or lay the work piece in your soldering area
and solder away!

If your workpiece is really hefty, build a back /side wall with
charcoal bricks to help hold/reflect heat.

Know the bracelet will have to come up to temp to solder… so
watch the bezel(s) carefully and avoid overheating them. Use a big tip
( prestolite #3) and soft brushy flame.

( again I’m assuming you have one of the highly dangerous "plumbers"
air-acetylene torches that has gotten so much attention lately) ( yes
I’m grinning- but they’re a good entry level torch.)

Don’t try it with a micro torch…They are cute, but they don’t
have enough BTU throughput to solder a silver beetle onto a large
bracelet. Maybe a gold one… but not silver. (laughing) )

And last, but not unimportant… don’t forget to remove the iron
binding wire before pickling!

You can see pics of a few bracelets that I’ve done on
skyblurocks.com.

The three bracelets shown are “hollow”… that is they have a front
and back.

I soldered them as described above with no problem.

yeah… the site needs a bit of work yet, updated pics, etc… but
it’s a work in progress- I keep trying!

steve