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The solder just does not flow


#1

Hello,

I’m fairly new to the world of silver jewellery and trying to solder
a 10 x 8mm bezel setting to a 2" diameter backplate using an Am Tech
Micro Torch without success! The solder just doesn’t flow, is it
maybe because I’m using too small a torch? Can anyone help?

Many thanks
Joan Custance


#2

Hi Joan –

I’m not quite sure how big the Am Tech Micro Torch is, but I can tell
you with near certainty that that’s your problem. Not enough heat.
When I first started making jewelry, I had some handheld butane
torches that I tried to make do with for a while, and quickly became
convinced that I had no idea how to solder. The 2" diameter back
plate is almost certainly sucking up all the heat – you probably
had no trouble soldering the bezel closed, but when you try to put
the bezel on the backplate the heat sink is too great for your torch
to handle. The only other thing I can think of is perhaps you forgot
to flux? But I think it’s the heat. One way you might be able to get
around this is to build a little 3-sided fort from charcoal blocks
that goes right around your piece. This will trap more of the heat
from the torch. I’ve used this technique on occasion when my torches
are running low on gas and I can’t stand to wait to finish
something. It’s still going to take a long time to heat up, and the
firescale that results will take some concerted effort to remove, but
it might be enough of a difference to flow your solder. You might
want to try soldering a smaller piece that your torch can handle so
that you can observe the color the silver is when the solder flows,
and then see how close to that color your larger piece is getting
when you heat it up. That should give you some idea of how close you
are to the soldering point. You could also possibly switch to an
easier solder – i.e. one that flows at a lower temperature.

Good Luck!
Hilary Park
www.hilarypark.com


#3
I'm fairly new to the world of silver jewellery and trying to
solder a 10 x 8mm bezel setting to a 2" diameter backplate using an
Am Tech Micro Torch without success! The solder just doesn't flow,
is it maybe because I'm using too small a torch? Can anyone help? 

Yes, the reason is that your torch is too small. Silver has the best
heat conductivity of any metal, used in jewellery. Process of heating
a metal, has a point of equilibrium. Torch adds heat to metal. At the
same time, metal gives heat away to surroundings. Torch should be
able to supply enough heat to overcome tendency of metal to cool off,
and more to raise temperature to the required level.

Another way to look at this, is like filling a bucket, which has a
hole, with water. If hole and pipe, which supply water, have equal
cross-section; it would be impossible to fill such a bucket with
water.

Soldering is the same. In order to raise temperature to required
level, a torch must supply enough heat to compensate for the loss,
and add some, at the same time. The heat loss gets larger as
temperature raises. With small torches, once some level of
temperature is achieved, no further progress is possible, because
head added is equal to heat lost. In another words - an equilibrium
for particular torch/ metal combination, has been reached.

Leonid Surpin
www.studioarete.com


#4
I'm fairly new to the world of silver jewellery and trying to
solder a 10 x 8mm bezel setting to a 2" diameter backplate using an
Am Tech Micro Torch without success! The solder just doesn't flow,
is it maybe because I'm using too small a torch? 

Yes, your torch is too small. Suggest you go to a hardware store and
get a torch of the sort that screws on to the top of a small propane
tank. It should have a tip which gives a pointed flame.

That’s the minimum. Better is a Prestolite, which operates off an
acetyline tank and which should be available at a store which sells
welding supplies.

Jerry in Kodiak


#5

Joan,

You’ve asked a lot of good questions.

Here are some for you.

What manufacturer did you purchase your soldering from? Solders from
different manufacturers flow at different rates.

What kind of gas are you using? It might not be hot enough to flow
solder on the mass of metal you are soldering to.

Micro torches often don’t heat the back plate sufficiently in order
for the solder to flow. What kind of metal are you using? What is the
width of the metal? What kind of solder are you using, Medium?

If you have a lot of metal mass, it will need a sufficient amount of
heat for the solder to flow. Pinpoint torches are meant to heat at
directly at the source. Silver or copper need to be heated up slowly
in order for the solder to flow.

Lastly, how is the fit between your bezel to the back plate. If you
have gaps and it is lacking a clean, tight fit, it will not flow
correctly.

karen christians


#6
Another way to look at this, is like filling a bucket, which has a
hole, with water. If hole and pipe, which supply water, have equal
cross-section; it would be impossible to fill such a bucket with
water. 

Leonid, what an excellent analogy! I learned this in my first
fabrication class with Don but your words explain the reasoning
behind the method so well. Thanks.

Michele


#7
The solder just doesn't flow, is it maybe because I'm using too
small a torch? Can anyone help? 
  1. Are you using flux?

  2. Is the metal and solder very clean?

  3. Are you heating the solder, or the metal? Heat where you want the
    solder to go, not the solder.

  4. Are the pieces of metal you want to solder very close together?
    They want a tiny gap, maybe 0.2mm- I’ve never measured it, so
    someone else might know better.

  5. Is the metal hot enough? If the metal is glowing bright red, and
    the solder doesn’t melt, then your torch is hot enough; the
    problem must be something else.

http://primitive.ganoksin.com


#8

Maybe the torch just doesn’t generate enough heat. Silver is an
extremely good conductor of heat and thus a largish piece takes a
lot of heat to get up to soldering temperature. A 2 inch backplate,
50mm in my measure, even using 0.3mm sterling sheet and fine silver
bezel wire is a lot of metal to heat. I haven’t made bezels of this
size the biggest I have done is maybe 25 by 30mm. When soldering
bezels of this size I place them on a stainless steel gauze mat on a
tripod and heat from underneath using the #6 tip on my Smith’s little
torch running on oxy-propane or even at times the rosebud heating
tip. When the solder starts to flow quickly bring the torch around to
heat the top. Before I had the oxy setup I usually used two torches
and the assistance of my partner to do the job.

All the best
Jenny


#9

If the silver base is sitting flat on the soldering block then it is
harder to heat up the whole item because the heat can only be
applied from one side and the block will absorb a lot of heat.

Placing the silver base onto a ‘mop’ or a few iron wires will raise
it off the soldering block and allow some of the flame to go under
the silver. This also makes the soldering block reflect heat into
the silver rather than absorb heat as when the silver is sitting
directly on it.

Alastair