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Paste solder difficulties

#1

I have been experimenting with paste solder to join the two halves
of copper and sterling beads. Sometimes it works, sometimes it
doesn’t. Mostly, it doesn’t!

I put the paste on the edges of the top half of the bead in order to
use gravity to assist with flow.

Often it seems like the pieces are joined, but on quenching in water
and with a very little pressure, the two halves come apart. The
solder leaves a granular residue that needs some pretty serious
effort to grind off in order to start again. Quite often the solder
is in grainy clumps right where I first put it, without having flowed
hardly at all.

Should I be using flux? The paste itself is supposed to contain
flux, and instructions on the pack say not to use any extra flux, so
I haven’t been using any extra.

When I hammer solder wire and place pallions on the joins with flux,
I don’t have any trouble, but using the paste - if only I could work
out how to do it correctly! - would save so much time. I make an
awful lot of beads (I love 'em, and so do my clients, thankfully!)
and to be able to use the paste solder would be a godsend. I’m using
the easy paste solder from Rio. I know there is an independent
manufacturer out there making all kinds of paste solders: would I be
better advised to use that brand?

Most of my beads are no bigger than 3/4" in diameter, most often
around 5/8" or a bit smaller, and I’m pretty sure my torch is
throwing out enough heat - but maybe it isn’t? I’ve been using a
jumbo butane torch for years which has been perfect for most of my
other work, and works fine with solder pallions, though I’m awaiting
delivery of an EZ propane torch right now. I’m not able to have an
acetylene nor oxygen tank in my studio because of fire regulations
here and my insurance company’s rules.

I have the most difficulty with the copper or bronze beads.

Any comments will be most gratefully received!

Janet

#2

Hi Janet

It sounds as if you are doing things correctly, but it also sounds
like your solder is not getting hot enough and is not flowing
properly.

If your torch has enough heat to melt pallions, it should have
enough heat to melt easy paste solder. In fact it should be easier to
get the paste to flow than to get the pallions to flow. Note that the
EZ torch that you ordered is a great torch for the type of work you
do. I use the Orca torch which is identical to the EZ torch.

The paste solder from Rio that you are using should work just fine.
The other paste solder supplier that you are referring to is Unique
Solutions.

I regularly use paste solder from both suppliers and both are
excellent products.

As you have suggested, you should not have to add any flux as the
Rio paste solder (and the Unique Solutions paste solder) comes
premixed with the appropriate amount of flux.

So far I have told you that you are doing everything correctly, yet
you have not been able to solder successfully. So I have a couple of
suggestions/comments:

Seams must be clean and must fit/align well (I assume that you are
already doing this, but had to mention it anyways)

When heating the bead halves, heat them with a soft bushy flame and
bring the halves up to soldering temperature slowly so that the
entire bead is at soldering temperature. Watch the seam carefully and
you should see the solder turn bright silver (just like with the
pallions) and flow around the entire bead seam. Try to hold the
entire bead at soldering temperature for a few seconds after the
solder flows. This will allow maximum time for the solder to flow
properly. You should be able to do this without melting the bead, but
it takes a bit of practice.

Make sure that when you apply the paste solder, you apply a very
thin film to the entire bead seam. This will ensure that you have
flux on the entire bead seam and maximize your chances of preventing
oxidation in the seam

If the above does not solve the problem, then as a last resort, I
would coat the bead halves with a thin film of flux like Handy Flux
or Grifflux. The reason I am suggesting this is that copper oxidizes
quickly and maybe there is just not enough flux in the past solder to
handle the additional oxides that copper seems to generate (vs
silver).

Good Luck
Regards
Milt

#3

Hello Janet

I use paste solder for 99% of my silver jewelry. The solder is OK,
you just need some practice. I also sometimes burned the solder,
that is what happened to you. The silver or copper is not hot enough
but the solder already lost all the flux and then will not flow just
form black specks and few silver granules.

My advice is put the solder on the top half of the bead as you did,
gentlyheat until you see smoke, let cool a bit for 3-5 sec then heat
again, let cool for 3-5sec, you will see that the solder is
gray/white and thereare no liquid flux, heat again but watch that
will not bubble, when become the solder brown/black then heat with
full flame. Heat first the bottom half of the bead. When soldering
copper beads use bigger flame and do thesoldering at once, no
cooling, the copper must be clean, grease free. Use sand paper to
clean the edges. Quench in pure alcohol then in sulfuric acid to
remove any firescale and flux, neutralize in bicarbonate of soda,
wash with tap water.

Hope this helps.)
Rudolf

#4

Hi Rudolph,

Um, just a data point here, but having sulfuric acid to dunk things
in to clean, is well. kinda dangerous. Curious in where you got this
technique.

5 tablespoons of sodium bi-sulphate, or pH Down for swimming pools
to 3 cupsof water is fine. Add acid to water, not the other way
around. Heat in a small crockpot. Use copper tongs. Basic pickle
that cleans silver, gold, copper and brass. Citric acid works well
too.

Pickle juice also makes a good cleaner. Fabrege did it, hence the
name Pickle.

Karen
Karenchristians.com

#5

My Unique solution is the best paste solder made. Rio stuff is OK.
but i have a lot of problems with their formulas- as it’s
inconsistent and its who know how long and doesn’t come in nearly the
flow point options Beth Katz’s older come in. Her range is great for
people using a lot of sterling or alloys with high copper content. My
student that use pastes use it faithfully- but any paste can burn up.
and that’ what you are describing- happen to everyone when learning
to use pastes successfully! Get some scrappy metal and practice you
will get the hang of it- and most often its unclean metal and trying
to “fill in gaps” with solder paste- Just like paillions or wire
Solder doesn’t work like caulking: It Does Not fill In gaps with
metal! So getting the pieces in the join to line up flawlessly is the
secret.

Prepping the metal is the MOT IMPORTANT POINT in using pastes. it
must be absolutely clean and flush (no light showing between any part
of the join) I also instruct my students to build up some layers of
CUPRONIL(i have no affiliation with 4S labs but its the BEST
firescale preventative and flux on the market hands down over
supposed “ceramic containing” firescale preventatives) on their metal
by heating the metal parts to join and spraying a light coat of
CUPRONIL on them -then repeat a few times until you have a nice
whitish coating on the pieces to be joined Although all pastes say
don’t use flux the Cupronil is to protect the metal and assist in
flowing the metal particles, in your case, around the hemispheres,
so that a good join can happen. Also squirting some of any paste out
and mixing it thoroughly with a toothpick is a reasonable method if
you are going to join a bunch of beads at the same time You can
remove the plunger on syringes of paste solder and use a bamboo
skewer to mix the ingredients You may have noticed a separation when
you open any syringe type product or some evaporation may thicken it
a bit or hot weather and an open window studio that evaporates
liquids out of many studio consumables- thinning may be required on
open paste solder(s). Most product gives you instructions on the
thinner they recommend with their formula (often it’s mineral
spirits- but by the drop relative to the amount of paste needed to
join 2 things! and then the vapours become more toxic so a good
respirator and fume redirection is even more necessary ( if you were
to poll the jewelers out there you would probably be surprised at the
number that do not bother with even a particulate reducing face
mask!) I highly recommend the MY UNIQUE SOLUTIONS range- a good start
is her “Hard” and a medium since there are a lot of flow points she
covers for silver and sterling silver - It depends on how many
operations you typically use in your designs and then in fabricating
to complete the joins so if 2 is the most solder operations you
typically require to finish pieces, then M.U.S. hard is best and
then a few steps lower ( easier flow temp) would be the best choice
as you don’t want a flow temp too close to your hard solder a it can
remelt too easily if you are learningYou can combine a paillion with
a paste on the same piece -I would use the paillion of hard with the
paste in a low flow medium of high temp “eaay” may work for you.

If you have any questions feel free to contact me off list.

Best Regards rer

#6

Once again I’ve been blown away by the expertise and sheer generosity
of Ochidians! My thanks to all of you who have taken the time - on
and off line - to reply to my plea for help with using paste solders.
I have enough info to keep me going and experimenting for a long
time. Love you guys!

Janet