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Another Soldering question


#1

Hello folks, I’m having a soldering problem and I have no idea why.
I’m trying to solder a 22 ga. Sterling silver wire ring around a 4
ga. sterling rod using hard paste solder. My wife bought the solder
and the clerk told her it was hard. The metals are very clean,
degreased, lightly sanded (800 grit silicon carbide wet dry paper),
properly fitted, everything I could thing of…and I can’t get the
solder to flow. On one try the 4 ga. sterling rod actually started
slumping into a fine little melt and still the solder didn’t even
act like it was going to flow. Am I missing something here? This is
my first run at using paste solder. I figured that, if the rod was
at the point of melting, I’d at least get something like fusion
going on. All I got was a messed up piece that had to be started
over again.

I was holding the 4 ga.rod vertically with the 22 ga. ring
surrounding it at the top. I’m trying to solder them together right
on the end of the rod. I heated from below the join and tried not to
play the flame directly at the joint to try to avoid melting the
small ring or burning it up before the rod got hot enough. I was
trying to be as judicious as possible with flame control.

I considered pickling both pieces hot to bring the fine silver to
the surface but I’m afraid that would only contaminate the join.
Enough of this novel. I’d really appreciate any suggestions here.
Thanks folks.

Mike


#2
I'm trying to solder a 22 ga. Sterling silver wire ring around a 4
ga. sterling rod using hard paste solder. 

Hello Michael,

I’m afraid I can’t offer much other than to second your experience
and hope someone comes to our rescue. I too am working with Hard
paste solder and sterling and am having more or less the same problems
as you, though with intermittent successes.

What I’ve observed is that the paste solder is likely to behave in
this “no melt no how” way under any of the following conditions
(using a torch):

  • if the paste dries out, even for as little as an hour before you
    apply the torch the soldering will fail. Based on what I’ve read
    elsewhere here on Orchid there are apparently paste solders that do
    not dry out.

  • if the torch flame touches the paste solder (and burns off the
    flux?) the soldering will fail.

  • if the joint is not 100% scrupulously clean, failure. It seems as
    if the fluxing action of the pasty part of the paste solder is
    relatively weak but I’m only guessing.

  • if you bring the joint up to heat too slowly (thereby burning off
    the flux in the paste?), failure.

  • if you’re using some kind of fire scale protectant and it flows
    into the paste solder, failure. I know from experience that in the
    same situations using solder chips instead of paste the protectant
    flow would not be a problem.

And last but not least, success seems more likely --though by no
means assured-- if you solder on charcoal instead of firebricks. I’m
guessing that the charcoal is sucking up the oxygen and therefor
decreasing the likelihood of oxides forming at or around the joint
when the metals are up to temperature, thus giving the paste solder’s
flux less work to do and thereby increasing the likelihood of success.

Like you I’d like to know what the real story with paste is because
when it actually works it’s pretty hard to beat for overall
convenience and applicability. Unfortunately, for me at least, those
successes seem few and far between. I’ve tried searching the web for
this kind of info and there seems to be precious little hands-on
"this is what you do and how you do it" info to be found.

FWIW I know it’s been said here before that paste solders are more
suitable for the kiln and furnace than the torch but I’ve read enough
here and elsewhere to make me wonder if it’s really as simple as that.

Hopefully some knowledgeable person (Beth Katz?) will offer up the
secrets of using Hard paste solder with the torch and put us out of
our misery.

Cheers,
Trevor F.


#3

Hi Trevor and Michael,

Hopefully some knowledgeable person (Beth  Katz?) will offer up
the secrets of using Hard paste solder  with the torch and put us
out of our misery. 

Thanks for the vote of confidence.

Unfortunately, over the years, many have bought paste solder that
had a tendency to dry out. Yes, … this is a disaster when it
does dry. It did not work due to the components of the product. The
shelf life was also very short.

f the paste dries out, even for as  little as an hour before you
apply the torch the soldering will  fail. Based on what I've read
elsewhere here on Orchid there  are apparently paste solders that
do not dry out. 

The good news… There is a non-drying formula from Unique
Solutions; a silver (or gold) paste solder formula that does not
dry out!!! Imagine that. This formula stays viable for a very
long, long time. I have had two test samples of paste solder on my
bench for over 4 1/2 years. One is in a small jar (plenty of air in
the void), the other is in a syringe. I do nothing special to keep
them viable, I do not even cover they syringe tip. They have not
dried out, so the product is still able to be used. I do use this
sparingly, about every 6 months, just to test the viability of the
paste solder. STILL WORKS just like the day I put them there. The
"old" products that were manufactured years ago has given lots of
people fits when soldering and has also caused some to not want to
try again! Believe me, paste solder works and works well. There are
lots of applications that just beg to have paste solder applied.

There are several descriptions and on my web site of
"How to use paste solder". It is sort of the walk through you
suggested. Check it out so that you can feel more comfortable
knowing that there is a paste solder that works.

After application to the piece and the first heating of the solder,
there will be a small flare up. This, in our products, is normal.
This does not change the viability of our solder in any way. The
flux is all self contained in the paste and does need to flow in
order to get the process started. If you do, however, heat and
heat and heat, you may burn out some of the flux and may have a
problem, not probable but do not overheat to such an extent that it
does happen. Always work in a well ventilated place at all times
when soldering, no matter what products you are using.

You need to make a conscience decision to solder; if you are
soldering silver, to go in with your torch and get the metal hot.
Do not place your torch flame directly on the solder itself or you
may run into a problem with any kind of solder, be it paste, sheet
or wire. One of the “secrets” of paste solder is never go in and
out checking all the time to see what is going on. The more air
you get into the mix the more problems you may have with any
solder. Go in with determination. I am not suggesting that you
overheat your piece, just be aware of what you are doing and commit
to solder that first time you are heating the metal for that
particular part of the operation and then heat the join. It does
take an exceptional amount of heat to burn out the flux in our
paste. Solder will flow towards the heat, use this to your
advantage. If you have heated the metal sufficiently, the solder
will flow directly into the join as you draw the heat over the seam
or join.

When using a powder solder, it is imperative that you use a very
heavy duty paste flux (Handy Flux as an example) to stand up to the
heat of soldering; again, if you back off the flame with the powder
solder, you can stand a chance of the paste flux will burn out
giving you a very crusty problem. With powder solder, stay with
the project and come into the project with the idea of a hot and
fast flame (not hot enough to melt the metal) and get it done in
all one application of the torch. Also, practice make perfect in
any skill. It may be a good idea to see how the non-drying formula
of paste solder works. Take a scrap, prepare a seam and go to it.
This will be more than adequate for you to see the advantages of
using paste solder. The many different melting temperatures
available help the jeweler and metalsmith make many soldering
points on any project.

if the joint is not 100%  scrupulously clean, failure.  It seems
as if the fluxing  action of the pasty part of the paste solder is
relatively weak  but I'm only guessing. 

Paste solder is more forgiving that other flux used with wire or
sheet (pallions). It has more ingredients in order to make the
paste flow smoothly. It holds up for a longer time than a yellow
liquid flux. One thing is that the area to be soldered must be
free of any pickle, as that will not allow any flux to work if that
element is present. If you have any idea that pickle is in your
seam, clean well with a baking soda soak and rinse with clean water
and try again. Good soldering habits must be maintained no matter
what solder you use. If you have lots of contamination, no matter
what products, solder just will not flow. The hard solder formula
also tends to fill tiny gaps. I do not however call it a "filling"
formula, but it does seem to fill in small pinholes.

if you're using some kind of fire scale  protector and it flows
into the paste solder, failure.  I  know from experience that in
the same situations using solder  chips instead of paste the
protectant flow would not be a  problem. 

I have not had any problems using a “normal” fire scale protector
such as boric acid and denatured alcohol. Works all the time. If
some of the other products have given you problems such as Cupronil
or Stop Ox, then simply discontinue use and go to the boric
acid/alcohol.

I have not tried the other products in recent years, so I cannot
speak to the efficiency of their use with non-drying paste solder.
Put that on my list of things to try.

And last but not least, success  seems more likely --though by no
means assured -- if you solder  on charcoal instead of firebricks.
I'm guessing that the  charcoal is sucking up the oxygen and
therefor decreasing the  likelihood of oxides forming at or around
the joint when the  metals are up to temperature, thus giving the
paste solder's  flux less work to do and thereby increasing the
likelihood of  success. 

I love charcoal for all applications, but I have had no problems
using the firebrick. It is all how you apply the heat of the torch
flame to your project.

    Like you I'd like to  know what the real story with paste is
because when it actually  works it's pretty hard to beat for
overall convenience and  applicability. Unfortunately, for me at
least, those successes  seem few and far between.  I've tried
searching the web for this kind of info and there seems to be
precious little  hands-on "this is what you do and how you do it"
info to be  found. I do hope that my explanations will be of help
and that you are  encouraged to try an organic binder paste solder.
FWIW I know it's been said here before  that paste solders are
more suitable for the kiln and furnace  than the torch but I've
read enough here and elsewhere to make  me wonder if it's really as
simple as that. 

When soldering in a kiln, a specific atmosphere must be maintained;
that is not a good alternative for a bench jeweler. It is not as
simple as sticking it in a kiln to solder.

The paste solder works fine, its just investing a little time in
investigating the proper way to use the paste and doing an
experiment or two to see how you can control it yourself in the
application that you are creating. Happy soldering.

Beth Katz
http://www.myuniquesolutions.com

Unique Solutions, Inc. Paste and
Powder Solders for Jewelers and Metalsmiths


#4
and I can't get the solder to flow. On one try the 4 ga. sterling
rod actually started slumping into a fine little melt and still the
solder didn't even act like it was going to flow. 

Try putting a little bit of standard paste soldering flux on the
joint before you add the paste solder. You’ll need to dilute it
slightly, so it’s a thinner liquid, and use just a very little,
drying it with the torch before you then add the paste solder.

Some paste solders are formulated for use in soldering furnaces.
These things use controlled atmospheres, and if starting with clean
metal, very little fluxing is then needed. When you then try and use
such a paste solder with a torch, results can be as described, as
there’s then not enough flux to keep the metal (either the joint
metals, or the tiny particles of solder) clean enough to flow.

Be careful to use only the smallest amount that you can, of
additional flux, since you don’t want so much flux that the melting
particles of solder float above the silver…

If, as i surmise, your problem is with excessive amounts of
oxidation preventing solder flow, you may also be able to get good
results by switching to a larger torch, or torch tip, and then
adjusting the flame to be a quite soft, gentle, and large flame that
fully envelopes the whole piece, or at least the joint area, in a
nicely reducing flame. That would then mimic, somewhat, the
atmosphere found in those soldering furnaces…

Peter