Struggling with soldering sterling silver

Jewelry Discussion
1

Hello Everyone,

I have a question regarding soldering sterling silver.

I have just realized that my solder joins are not really “joining”.
(yikes) And I am not sure what I am doing wrong…

So, I began to practice soldering again. I did the below more than 30
times, with the same results :frowning:

The set up: (I tried 2 different joins)

join #1-
15mm long, 2x1mm rect wire, on a charcoal block. 5mm long, 2x1mm
rect wire, laying across above wire. (kind of like a cross) secured
with a “staple” (made from small paperclip), also used pins…

join #2
20mm long, 2x1mm rect wire. mitered 5mm in from end, bent to a 90
degree “L” shape.

pieces sanded/filed flat, join is flush and clean. pieces fluxed
with grifflux #1. (I made a new batch of flux.) used one chip Rio
Hard sheet solder. (I used Rio med solder a few times as well).

used Smith Little Torch with #5 tip flame is approx 20-25mm long,
with a soft tipped blue cone. (I tried bigger and smaller flames as
well.)

I heat up the piece, watching for the flux to go clear and glassy.

then one of 2 things happens:

  1. the flux goes clear, but the solder doesn’t flow, and the piece
    starts going “bright orange” then the solder flows as the surface
    of the metal goes “shiny”, so I pull the flame off.

  2. the flux goes clear, and the solder flows before the piece starts
    going “bright orange”.

I pickle, then pull out the piece, and look at the join. I see a
solder “fillet” all around, so I think the join is good.

The problem:

Then, I take a pliers to check the join, and the 2 pieces pop
apart.

I then examine the 2 pieces, and on each piece I see a “broken
fillet” around where the 2 pieces touched, and where the pieces
touched there is a “fine, crusty, white residue” which sometimes has
some color in it (yellow, rust, brown, black). It appears that the
solder is not going “thru” the join".

The questions:

why is my solder not flowing thru the join? what is this crusty stuff
and why is it occurring? (is it flux?..)

I have not heard/read anything about this yet, and have been under
the impression that my joins were ok, so I never asked while in the
classes…

Any help would be greatly appreciated…I’m stuck in neutral.

Thank You,
Julie

2

The charcoal block is absorbing the heat, so the pieces are not
heating evenly.

mike w

3

Julie:

Try putting your solder palions behind the joint and pull the solder
thru. it also sounds like you may have flux issues and it may have
evaporated some of the liquid and is now to strong. Many self
pickling fluxes will cause problems if you use tap water to replace
the liqquid as it has mineral content from rusty pipes, solder,
asbestos and a host of otherthings including chlorine and flouride
which will react also. Nice huh? Use distilled water for your shop!

Ringman John

4

Hi Julie. It sounds as though you’re doing (almost) everything
correctly. Perhaps your flux is contaminated, though. Consider
trying a commercially prepared flux such as Battern’s or Prip’s.
Also, you don’t mention using a firecoat. Before fluxing, I dip all
pieces to be joined in a solution of denatured alcohol and boric
acid in a 50/50 ratio, then burn it off. This removes residues that
can prevent a good join, and helps prevent firescale. Try this first
before replacing your flux.

I often use a charcoal block to solder large pieces of sterling,
since it can help maintain heat and provide a reducing atmosphere
(and help prevent firescale), but it may be creating too much heat
for such a small join.

Solder follows the heat, so using the charcoal block the way you are
may be hindering you. Try placing the two pieces to be joined in
tweezers and suspended above your surface so that you can direct the
torch flame underneath the join. Place your solder on top and heat
from underneath. This should draw the solder around and through the
way you need it to. Please let us all know how you solve this
problem.

James in SoFl

5 
          The charcoal block is absorbing the heat, so the pieces
      are not heating evenly.

Agreed. Heat control is urgently required. Both pieces need to be at
the same temp, and I suspect the lower part (of the two that are
crossed) is not getting heated enough while the upper is getting
heated well enough for the solder to melt onto it alone.

In such cases, and I had a similarly awkward one myself recently,
heat on stainless steel mesh perhaps on a tripod, and watch how the
two pces heat up. If one is missing out on the heat consider heating
from below as well as from above.

Brian

Brian Adam
Auckland NEW ZEALAND

6 
Thanks to James for this tip, but how do you achieve that 50/50
ratio of a liquid and a solid?

Perhaps I stated it incorrectly. I start with a clean, empty Skippy
Peanut Butter jar. First, I fill it approximately one quarter full
(by volume) of boric acid. Then I fill it to half (again, by volume)
with denatured alcohol. Finally, I shake until it is as dissolved as
much as it will get. In my world, that’s 50/50. And no, the boric
acid doesn’t completely dissolve into solution and I never claimed
it did.

This is the ratio I use so that I can replenish evaporated alcohol
as needed. The classic recipe for this firecoat (or flux, if you
prefer to call it that) is to add boric acid to alcohol until
saturated, and agitate before use. You may fill the jar three
quarters full of boric acid if you

wish, with the remaining one fourth alcohol, and agitate before use.
It doesn’t matter, you’ll still have the same saturation of solution
when you use it. It isn’t a critical recipe.

James in SoFl

7

Instead of taking the time to mix the chems/solutions, I have used
Majic Dip for aprox 5 years. Yes , I know its alot more expensive
than mixing my own soldering dip, but its extremely effective in
eliminating oxidization during the soldering process. Also, it makes
my cleanup afterwards a snap. Its available at most supply houses.
As with most ready made products versus homemade products, the
expense is in the convenience.

Buy-shake-dip-solder-rinse-done! If you are running a large volume
of soldering jobs daily, you will appreciate the convenience. If you
are working a low volume of projects, maybe the homemade mix is
right for you. Warning- A local jeweler/friend/competitor knocked a
container of alcohol/boric acid solution over on his bench while he
had a flame going, and the entire surface of his bench was instantly
in flames. Whereas the Majic Dip is nonflammable. I wouldnt dream of
running out, nor going into Christmas without 3-4 bottles ready to
go. I am not associated with the product in any way-simply a very
satisfied user.

Ed in Kokomo

8

Hello Silversmiths,

Orchid participants have for years asked and answered the question of
how to prevent firescale (copper oxidation) from surfacing during the
soldering process. Orchid archives can be reviewed for these answers
but in a nutshell…

Prips flux works 100% of the time when properly applied. Prips has
Never failed to keep sterling silver completely clear of firescale
under any soldering effort that we have undertaken in our shop. And,
for extended gold soldering it also has the advantage of limiting
surface clean up. The combination of denatured alcohol and boric acid
is great for diamond and gold protection but will not adequately
protect silver to the extend of Prips. It works for our extensive
repair business…

Gary Dirks
Janine’s Jewlery
Redding, California

9

Hey James, are you using boric acid powder or boric acid granules?
I’m using the granules and doing pretty much what you describe. The
firecoat works well (which I guess means I shouldn’t fret about it),
but the solution is clear, with undissolved granules at the bottom.
My metalsmithing friends all seem to have milky white boric acid
solution, so I guess they’re using the powder.

Seems to me the results are the same, but I just wondered if I’m
doing something really weird. It wouldn’t be the first time :slight_smile:

Cheers,

Jessee Smith
www.silverspotstudio.com
Cincinnati, Ohio

10

Ed, I think you just made a good case for not using the
alcohol/boric acid firecoat mix! I previously used it and had it
catch on fire several times. Not a good scene. The Prip’s mixture
is made with water and, of course, is not combustible. Not just
safer but works well too!

Cheers from Don at The Charles Belle Studio in SOFL where simple
elegance IS fine jewelry! @coralnut2

11 
    The combination of denatured alcohol and boric acid is great
for diamond and gold protection but will not adequately protect
silver to the extend of Prips.

This is what I typed in my original post:

  Consider trying a commercially prepared flux such as Battern's
  or Prip's. Also, you don't mention using a firecoat. Before
  fluxing, I dip all pieces to be joined in a solution of
  denatured alcohol and boric acid in a 50/50 ratio, then burn it
  off. This removes residues that can prevent a good join, and
  helps prevent firescale.

The primary reason I use the alcohol and borax is to clean the metal
and remove oils and residues. I always use Prip’s after that
firecoat. I know my posts are wordy, but did you actually read the
whole thing?

James in SoFl

12 
    Seems to me the results are the same, but I just wondered if
I'm doing something really weird. It wouldn't be the first time :)

The weirder, the better :slight_smile: The granules work as well for me as the
powder, but the powder seems to dissolve easier. Borax is borax,
when it is 100% borax.

James in SoFl

13 
    I think you just made a good case for not using the
alcohol/boric acid firecoat mix! I previously used it and had it
catch on fire several times.

Hello Don,

I suggest that this is really a personal preference thing. For
instance I prefer the alcohol mixture for a number of reasons
including fast drying --breath on it or hold it several inches above
your hotplate and it’s instantly dry-- and less puffing once you
bring the torch in. Of course there are drawbacks too, not the least
of which is that the alcohol is simply a carrier since it doesn’t
dissolve the powders into solution, but that’s where the “personal”
part of the preferences come in.

I’ve been using alcohol based solutions for well over five years now,
almost exclusively so since I started mixing my own fluxes and
firecoats, and never had a single (unintentional) alcohol fire. I
think it comes down to one’s habits of safety: a bummer to learn but
easily repeated.

Cheers,
Trevor F.
in The City of Light

14 
        I think you just made a good case for not using the
alcohol/boric acid firecoat mix! I previously used it and had it
catch on fire several times. 

        I've been using alcohol based solutions for well over five
years now, almost exclusively so since I started mixing my own
fluxes and firecoats, and never had a single (unintentional)
alcohol fire. I think it comes down to one's habits of safety: a
bummer to learn but easily repeated.

Since I was the original poster on this, I’d like to chime in once
again. I mentioned that I use a plastic Skippy Peanut Butter jar to
mix and store this firecoat. I always agitate (shake the jar), dip
the piece(s) to be soldered, RETURN THE LID, then burn off the
firecoat. ALWAYS. I knew how hot alcohol burns long before I ever
used it for this purpose, and always feared spilling it. Please be
careful if you’re trying this lately. Imagine the jar of alcohol
catching fire, THEN spilling!!! Close the lid before you burn, and
keep it separate from your workbench, off to the side.

James in SoFl

15

Trevor,

I agree with you that using a particular flux is a very individual
thing. Strange isn’t it? You prefer a paste over the liquid while I
prefer the liquid over the paste. You feel the Batterns is too weak
for higher temp work whilst I have no problem with it. A lot
probably depends on torch control amongst other things. Anyway, its
a subject that will never totally be resolved and we each have to
decide what works best for us. It does make it a bit difficult for
the newer people though.

I find the same is true in other operations as well. I have students
who would rather heat from the top while soldering bezel to backplate
though I teach back heating. Nonetheless, after they try my methods,
if they prefer the top heating, I tell them to go for it. To each his
own.

Cheers from Don at The Charles Belle Studio in SOFL where simple
elegance IS fine jewelry! @coralnut2

16 
    I find the same is true in other operations as well.  I have
students who would rather heat from the top while soldering bezel
to backplate though I teach back heating.  Nonetheless, after they
try my methods, if they prefer the top heating, I tell them to go
for it. To each his own.

I love it, Don. I start from the back, move to the top, then draw
the solder around from the back again. As Peter said, “It’s a bit of
a dance.” It’s also obvious we all develop our own dance steps.

James in SoFl

17 
I agree with you that using a particular flux is a very individual
thing. ... You feel the Batterns is too weak for higher temp work
whilst I have no problem with it.

Don, too true! Stuff like this is so individual that sometimes it’s
almost embarrassing to say things like “use this” or “that’s better”.
In the end it’s all “your mileage may vary” and one can only hope
that the reader takes it in that spirit.

As to Battern’s being weak for higher temp or dirty work I think it
might be worth mentioning that I’m not the only one who has found it
thus. In Tim McCreight’s “Complete Metalsmith” in the “Fluxes” section
he says pretty much the same thing:

  "Battern's: a flouride-based flux ... does not have the oxygen
  absorbing power of the borax fluxes and is not recommended for
  metals that oxidize rapidly such as copper, brass and nickel
  silver."

Clearly he’s talking about the same Battern’s formulation that I had
used and discarded. I think they’ve switched formula in recent
years, no? Maybe that’s made some difference in it’s performance too.
I wouldn’t know.

The torch one uses is obviously going to have some effect on this
too, as I think you mentioned. I’ve used cheap, un-adjustable
torches for much of my metalworking career and that’s certainly made
the flux issue a larger issue than it might have otherwise been.

... I use a plastic Skippy Peanut Butter jar to mix and store this
firecoat. ... Close the lid before you burn, and keep it separate
from your workbench, off to the side.

James, it sounds like we’re on the same page in terms of our ways of
using our alcohol-based flux though I tend toward the paranoid side.
What I do is mix in a large jar but transfer to a teeny 10 ml jar for
use on the bench. That way if something goes wrong, or the working
jar gets contaminated, then it’s not a big deal either way. Less
intimidating too. The basic cap-it-and-move-it procedure still
applies though, of course.

Cheers,
Trevor F.
in The City of Light

18

James in So Fla makes some excellent safety points about using
alcohol-based flux. I’d suggest using a jar/container that is wider
than it is tall. It will be much harder to knock over!!

If the container does catch on fire, smother it by replacing the
lid. (We old fogies remember when fondue was first popular, the
heating device was alcohol in a little lidded pan… the flame was
adjusted and smothered by placement of the lid.) The problem comes
when we are startled and act hastily!!

Judy in Kansas, where the tornado alert sirens are being tested. Is
it that time of year already??

19

Trevor,

I also saw Tim’s reference to Battern’s being a flouride-based flux
and right after reading it I checked the contents on a bottle of it.
It does not mention being flouride-based and only says it contains
borax! I don’t know if that is the formulation change you suggested
but…I also checked a very old bottle I got from an old jeweler and
it also says it contains borax with no mention of flouride. I do
see where Handy Flux does contain flouride along with potassium and
hydroxides. A quick check of other self-pickeling fluxes show some
also contain boric acid and amonium along with other brews. Not
sure where all these lie as the are all advertised as high temp
fluxes in the range up to 1700 deg.

All the more reason to pick a flux any flux!

Cheers from Don at The Charles Belle Studio in SOFL where simple
elegance IS fine jewelry! @coralnut2

20 
    James in So Fla makes some excellent safety points about using
alcohol-based flux.  I'd suggest using a jar/container that is
wider than it is tall.  It will be much harder to knock over!!

This is in the archives, a couple of times now for all of the years
that I have subscribed to his listserver.

I no longer use the alcohol with boric acid. It only acts as a
carrier for the boric acid. Long ago, I learned that it is often
necessary to clean the jewelry before firing, so rinsing the work in
boric acid/alcohol for cleaning becomes redundant. After cleaning,
between static, moisture and oils frmm my hands, boric acid powder
clings quite nicely to my work before I fire it up. I am sure that
boric acid crystals would not. Boric acid roach killer works great.

The last time I used boric acid and alcohol, I had about a decade on
the bench. I used an old wide mouth Handy&Harman flux jar for just
this purpose. Large enough for a bangle or charm bracelet and a lid
to extinguish it quickly when it did catch fire. That last time, I
didn’t realize the it was burning. I just noted a little stinging
sensation around the webbing between my left thumb and forefinger.
In trying to put it down gently, I bumped into something in my
benchpan, mandrel, pliers, mallet … who knows? I managed to slosh
it all over my hand. It left me with a huge blister on the inside of
the hand. The back of the hand lost something like 3 layers of skin.
The outer layer that might have formed a blister fell off in
minutes. It took a full 6-9 months to heal, I don’t remember
anymore. The guy I was working for offered no compensation and I
even had to pay my own hospital bill.

Here endeth the lesson. Take from it what you will.

Bruce D. Holmgrain
http://www.goldwerx.com
@Red_Rodder
JA Certified Master Bench Jeweler / CAD/CAM Solutions