Cracked solder joints

Hi every one.

I have been a jeweller for a bit over 20 years now and so am a
little uncomfortable asking this question.

When I was doing my apprenticeship I prided myself on no one being
able to find a join I had done.

Somewhere something has changed and I can’t seem to get to the
bottom of it.

Nearly every join I do has bubbles or a small… well crack. I can
almost guarantee that if I have to round the ring too much it will

I have read through the forums and tried everything. I have cleaned
my flux, I have used boiled water with my borax cone, purified water
and demineralised water.

I have heated fast and slow.

I have heated to just melting to glowing hot.

my joins can’t be any tighter so I try making them loose.

I heat from under the solder and pull it through and then I try on
top of the solder.

I never feed solder.

I tried using a little solder and then a lot.

I even emery the ring before I cut to get rid of the polished
surface. No matter what hardness solder I use I still seem to get the
little line on the side of the band.

Some one please help me I am going insane.
Thank you.

I’ll take a stab in the dark. Could it possibly be a bad batch of
solder? After 20 years I seriously doubt that it is your soldering
technique. Are there any other soldering variables that have changed?

I have been at the bench for 35 years and it seems like the quality
or working properties of metals has changed since the out sourcing of
jewelry manufacturing started. There seems to be a lot more oxidation
and staining of the metal than there used to be. Maybe it is a change
in the alloy formula or something of this nature.

I do know that the quality of construction has gone down. I recently
repaired a bracelet that had 28 ga. pins connecting the links and
people wonder why their bracelets fall apart in a year. And the
hollow construction requires MUCH more heat control or the jewelry
will melt in a heartbeat.

I wish I had a better answer for you…Teddy

Are you using the right temp solder? I know that if you use and easy
or ultra easy solder on a sizing joint, pits, porosity or even crack
will occur. You can even “pull” these softer solders out of a sizing
joint will abrasive wheel or buffs. Make sure you are using a hard
solder for sizing. You may want to try fusing the joint will the
same karat gold. The results will be better but is very risky if you
don’t know how to do it properly.

Hope this helps!
Steve Cowan
arista designs

Hi Darren:

I was always taught to use spit with a borax slate, but that’s been
a looong time gone. Don’t think that’s really your problem.

I’d be a lot more suspicious of your solder itself. Did you recently
get a new batch? Switch suppliers?

Are we talking silver or gold? (Gold, I assume?)

Does it happen with some karats/temps and not others? Do you have
any old stuff stashed away anywhere you can test against?

As far as a ‘line’ on the side of the ring, that’s just a bad color
match between the solder and the ring. Tighten up your joint, and
try to find a solder that’s a better match. If you’re talking pits
and cracks, thats much more likely a quality issue with the batch of
solder. If you haven’t already, pick some up from a totally different
supplier, ideally someone who makes their own, so you can be sure
you’re getting a completely different mix.

For whatever that’s worth.

Hello Darren, If nothing you are doing seems to have changed, the
pits and cracks you now get could be caused by a change in the
composition of the solder you are using. Can you check that and let
me know? Hang in there.

Tom Arnold

Somewhere something has changed and I can't seem to get to the
bottom of it. 

Once I was troubleshooting soldering problems for a jeweler. He had
enough experience so all basics could be eliminated. What happened
was that his window was facing a parking lot and he a habit leaving
widow fan on intake through the night to refresh air in his studio.
One guy with old car get to parking under his widow, so every
morning when car was started, his studio would get a blast of air
saturated with burned oil. The film would deposit on his bench and
crew up his soldering station. The car would leave and by the time,
he would come in the air would be “nice and fresh”.

Leonid Surpin

Perhaps you are becoming more critical. It’s not uncommon. The joint
problems were probable there all along. You most likely couldn’t see
them because your eyes where not seeing things the way you see them
now. Have you taken a critical look at something you made fifteen
years ago? Maybe I’m way off track, but I might be dialed in. I like
my older work, but I feel I could do it better now. I have always
tried to do my best, so at the time I could be proud of what I did.
As a final suggestion, welded seams don’t show because there isn’t a
seam once it’s welded.

Hi Darren,

I admire your willingness to ask the question. It demonstrates a
willingness to learn and continually improve your skills which gives
us the only real competitive advantage any of us can have.

This is very hard for anyone to put their finger on without watching
you do it and then picking apart your technique. I’ll give you a
little input, for what it’s worth. I’m assuming these are gold
solder joints. Please don’t be insulted by any of this
over-explaining, you probably know everything I’m about to say…but
maybe there is one little thing that might help you.

-If there are pits in your seam and your seam is as clean as you
describe, I would think you might try a softer flame and let it flow
a little longer, then let it go a little longer still. Sometimes you
will see little bubbles popping on the surface as they float out of
the molten solder. It sounds like an incomplete solder joint. It’s
possible you’re doing it too hot and too fast.

-We did have a guy in the shop who liked to use borax cones and was
have trouble with his seams as well. I asked him to switch to
Batterns flux and it cleared up his problems. I know there is
absolutely no problem with the cones, it was just a variable to
remove and it worked.

-If it’s white gold your having issues with, try using 20K white
weld. You’ll need to use a softer flame, you may need to start by
heating the solder more directly than usual, rather than from the
opposite side of the seam to get it started but you can then pull it
through the seam normally. You’ll want to let this flow longer than
you might normally…but careful not to melt the shank. We have very
few pitting or cracking issues when we use the 20K white.

Just for shop talk purposes and to help you pick apart your
technique, our procedure for soldering an average gold ring that we
are sizing down (forinstance) is this;

-Clean the ring.

-Cut out the piece with saw.

-Bend the shank together with 1/2 round pliers while being careful
not to deform or damage the ring in any way.

-If needed take a saw cut through the seam to true it up and then
bend it closed again.

-Put the top of the ring in cross-locking spring tweezers with the
seam up and the top of the ring down. Put the end of the tweezers
under your bench block.

-Cover the ring with boric acid and alcohol, light it to burn off
the alcohol.

-Pick up you piece of solder with your pick-up tweezers and dip it
into your nice clean little puddle of Batterns flux. Set it on top
of the seam.

-Set your flame on the soft side, but substantial enough to get the
solder to flow in a few seconds.

-With your clean solder pick in one hand and your torch in the other
begin heating the seam from the inside of the shank. Use the pick to
keep the solder from popping out of place as the flux evaporates.

-As the solder balls up, without removing the torch, you might use
the pick to position the solder ball over the seam. But it is likely
your picks work is done.

-Continue to heat the joint in a way that the solder flows freely
and equally on each side of the seam and draw it through to the

-Pick up the tweezers in one hand with the torch in the other and
heat the back side of the seam in needed to draw the solder
(normally not needed).

-If it’s not flowing, something is wrong, likely dirty. Stop and
pickle and possibly hang in the sonic. Try again. If still not
flowing…something is on there that shouldn’t be. Might have to cut
through the seam and super clean it…and try again.

Sorry so wordy. Hope it gives you something to try.

Best regards,

Hi all and thank you for all your responses. To answer several
comments all at once… this problem has been going on for some
years. I guess you just burnish the joint and on you go. I have
worked at several workshops with different solders and gases and
equipment. Still having the same trouble.

I have recently picked up a contract with a local shop to do their
repairs and they have specifically mentioned that they are
unsatisfied with getting bad joints from their current repairer. I in
myself am unsatisfied with having this problem and want to solve it.
I just can’t seem to land on why.

For those that suggested tighter joins, I really can’t get them any
tighter… really. It doesn’t seem to matter if I use hard or soft
solder although hard usually cracks more on latter rounding. I use
hydrogen by choice but it is the same with propane. I definitely
don’t overheat the solder - at least not every time - I am human :-p

As far as solders (gold)… well I don’t make them so can’t vouch for
their quality. I do have some solder here going back to my
apprenticeship which gives the same problem, as do the new ones. It
is for this reason I am convinced it is something I am doing. I just
can’t figure out what.

Kevin - it is true over time you do become more critical, however
sometimes these marks are quite visible.

I take it from this discussion that none of you have this problem -
which is even more depressing. Perhaps you could tell me what solders
and fluxes you use and I might have to try something else. I really
can’t afford to go buy all new solders at the moment but I may get a

Thank you for all taking the time to respond and offer you help.


It’s comforting to know that even the experienced among us often
have fundamental problems. My first impression was that - it’s not
you. Perhaps a different brand of solder, that solved the problem for
me, and it was just about the last place I looked. I couldn’t help
think - it’s me - turns out, it wasn’t.

Rgds…Ski & Cathy
Rocks to Gems


I agree. This sounds like a bad batch of solder. Do you have any
older solder to make a comparison?

There’s a project I have been meaning to work on. Thanks Darren.
Your response just propelled me to finally bring this to completion
in creating.

full spectrum chart of all the solders out there from at least six
manufacturers and all their flow points. Keep a sample of each with
the date of purchase, type, both gold and silver. The only way I
could ever prove that solder is a bad batch, is to compare it with
something that worked well at a particular date.

I have my likes and dislikes for certain manufacturers of solder.

If you would be so kind email me offline as to which solder you have
been using?


Karen Christians


One guy with old car get to parking under his widow, so every
morning when car was started, his studio would get a blast of air
saturated with burned oil. The film would deposit on his bench and
crew up his soldering station. The car would leave and by the
time, he would come in the air would be "nice and fresh". 

I think you tell a good story.

Enough of an oil film to be a problem and your jeweller would be
sliding out of his chair. Besides after 1000 F any oil would be
carbon (I usually solder on a charcoal block made of carbon with
trace crap added). If the metal is not encrusted with oxide and a
liquid flux will wet it I’m fine, no clean room soldering for me.

True there are strange things added to gas and oil but what comes
out the exhaust is pretty much controlled these days. If your guy
with the old car was burning leaded aviation gas I might be
concerned, but that is quite illegal under several sets of laws.

Demand Designs
Analog/Digital Modelling & Goldsmithing

Hi Darren,

If it is a problem with just this one ring it may be the alloy of the
ring. I have found that some white gold (in particular) alloys are
much harder than the solder so it can polish out and leave a wave.
The cadmium free solders may also be different in hardness then you
are used to if you have changed solders but I doubt that is the
problem you are having. The porosity you are getting is from the
solder being over heated or the metal not taking the solder. Chances
are it’s the alloy you are using. Try keeping the joint as tight as
possible and polish across the joint not with it. A split lap can
also help on the profile finish.

Good luck,

I had a similar problem some years ago. My problems started when my
bullion dealer changed their alloy of 18ct solders. they removed the
cadmium from the alloy. Cadmium in 18ct gold solders aids the flow
of the solders. There are some health concerns in the UK, over the
heating of cadmium alloyed metals. This meant that the cadmium was
removed from the solder alloys on so called health and safety
grounds. I changed my bullion supplier and found one who would
supply 18ct solders alloyed with cadmium on special order. May I also
thank all who have bought my book and sent me kind comments on my
work shown. Since the book has been available worldwide I have
received good comments from many craft people. I have been pleased to
answer any questions on manufacturing techniques and processes in
detail. If any others would like to comment on my book please do so,
good or bad.

Peace and good health to all
James Miller FIPG.

Hi Darren;

Sometimes when this happens to me it is a case of my torch tip
getting all carboned up. I put it in the ultrasonic for up to
1/2hour and all is good again. Sometimes I have to take a small
drill bit and gently clean out the inside. Hope this is of help.

Take care, Paul LeMay.

Long ago I had problems with pitting in the solder seam with both
silver and gold solders when using the oxy/lpg little torch. I tried
various fluxes and various flame compositions and some produced
better results than others, but a porous seam would be constantly
lurking to show up in the final polishing or sooner. The porosity
ranged from a line of miniscule pores in an otherwise perfect seam,
to obvious cavities in the seam or fillet caused by boiling solder.

The small fierce flame can easily overheat the solder because by
nature it must heat the joint hotter in order to compensate for heat
drain by conduction.

Going back to the larger softer gas/air flame gave me clean solder
flows. A bigger softer flame heats the metal more evenly with less
chance of heating beyond the flow temperature of the solder.

I found that more speed is gained by getting a clean solder flow the
first time.

Regards, Alastair

I use completely denatured alcohol and medical grade boric acid for
fire coat and the “house special” flux. Battern’s by any other

The cone used to give me fits, water as a firecoat carrier is awful.
If it doesn’t burn completely and cleanly, it’s not going to help a
solder joint. Water, even super-clean, doesn’t burn at all.

I would try completely denatured alcohol and boric acid as a

Dave Phelps

One reason this problem occurs is too direct heating of the solder
joint. If the flame is directed specifically at the seam, the outer
reaches of the area do not become hot enough to absorb the solder.
hence all the solder is concentrated solely at the joint, rather
than spread throughout the general area. And since the solder tends
to be softer than the surrounding area, it polishes out of the seam
easily, leaving a straight line visible. W/G is more prone to this
than Y/G.

Instead heat the area immediately surrounding the seam, with a
slight back and forth movement. Heat the area, not cook the seam.
Remember, you are soldering, not welding. In addition, clean tips and
properly adjusted fuel/oxygen adjustments help with proper heat

Ed R

Weird thing.

Other than having a spell cast on you (juuuust kidding), go to a
buddy who is soldering good joints. Then use his or her equipment,
and see the result.

Cheers, Hans

Darren- It’s my experience that pits are from dirt, over heating the
solder, or dragging out pits in the finishing.

I always steam out my joint where I cut it to remove any dirt or oil
from the saw blade.

I use a fire coat of alcohol and boric acid. I also use handy paste
flux that I have decanted into a tiny 1/2 inch jar so that when it
gets dirty I can clean it out and replenish with fresh and clean flux
often. I also never add my solder until the ring is up to temp. I
hold the solder on my pick near the seam, and as soon as it’s hot, i
then add it on the inside of the shank. I always use the highest temp
solder or fuse when ever possible.

If you over heat solder the alloy boils out and leaves pits.

To clean up, I always file the inside of the shank, then round up on
a mandrel. That helps burnish out the file marks on the inside. I
never file or emery the outside before it’s rounded up or the shank
will crack. I then file only 80% of the way and then finish with
emery. I never use a rubber wheel because the drag out pits. The same
with buffing. I take my stuff to pretty fine emery before I buff. The
less time on the wheel, the less pits drag out.

Good luck.
Have fun and make lots of jewelry.
Jo Haemer