I had an experience this week that was new to me, and I want to run
it by you, my colleagues, to see whether it is odd, or a common
thing that I have just never run into before.
I was almost finished with a commission piece in silver with a
couple of teensie three-knuckle hinges-- just “bringing up the fine
silver” before the final polish and setting. I was interrupted just
as I put it into my very hot citric-acid pickle. I got dragged into
a lengthy “thing”, forgetting about the piece for seven hours. When
I resumed work on it, it was dingy gray, but I’ve had that happen
before, and I just sighed and began re-polishing.
To my surprise-- and distress-- all the small solder joints fell
apart, including the hard-solder joints in the bezel strip, though
the bezels themselves did not come off. It took me til midnight to
fix the damage and finish the piece (I had arranged delivery the
next morning-- yesterday). The larger solder joints seemed fine, and
didn’t appear pitted.
Now, anyone could probably guess that it isn’t a good idea to leave
a piece so long in the pickle, but I feel fairly sure this isn’t the
first time I’ve done that. I’ve never had soldered joints fall apart
like that. I might wonder if something is wrong with my solder, if
the joints hadn’t been made with three different ones!
Anyone care to comment (other than telling me the obvious, that it
was a bush league mistake to leave a piece in the pickle when I was
called away)?
Leona, I beg to differ. When I was just a wee metalsmithing student
I was working on an intricate pendant with many, many hard solders. I
fluxed, soldered, pickled, fluxed, soldered, pickled, just like I was
supposed to. Getting ready to polish it, every joint along this one
structural “spine” element failed. Upon examination the failed seam
appeared to be crystalized. We surmised, correctly I think, that
repeated heatings and picklings changed the chemistry and physical
structure of the solder, leaving it brittle.
All of the failed seams were soldered and held up for quite a while.
What I learned from this was the the flux, solder, pickle litany was
not really right. I never pickle until the condition of the flux or
metal indicates that it is time to do so. Your eyes will always tell
you when the time is right. I believe that the pickle eats away at
the zinc in the solder leaving the alloy brittle and weak. Too many
unneccesassary heating/ pickling operations just aren’t great for the
project…
It wasn't the pickle --- the joints you thought you soldered
weren't. Thats why they came apart.
Pardon me, but I think I know when a joint is soldered-- I’ve been
doing this as my profession, and teaching, for a while now. If this
weren’t a novel occurrence, I wouldn’t have brought it up. But
thanks for trying to help.
I believe that the pickle eats away at the zinc in the solder
leaving the alloy brittle and weak. Too many unneccesassary
heating/ pickling operations just aren't great for the project....
I agree with Andy that too much exposure to pickle leaches out the
solder alloy making it brittle. A couple of years ago, I soldered
several dozen pairs of gold posts onto sterling earrings with hard
solder. The phone rang so I fished the earrings out of the pickle and
tossed them into a pan of plain water. I planned to rinse them off,
but the phone call went longer than expected and I completely forgot
about the earrings. The next day, I rinsed them off with baking soda,
dried them and went to twist harden the posts with a pair of pliers.
To my horror, the solder joints were brittle and the posts twisted
off. I ended up cleaning off the depleted solder and resoldering all
of them.
Even a very diluted pickle bath, albeit with long exposure
(overnight/10+ hours), was damaging to the solder.
As a matter of course, I never soak work in pickle any longer than
necessary and I try to do as many solderings as possible before
pickling. I often quick cool work in water or boric acid/alcohol
instead of pickle when doing a series of solderings. (NOTE: I take
special care not to spill or set the alcohol on fire when quenching.)
This minimizes the overall exposure to pickle.
Leona, I beg to differ. When I was just a wee metalsmithing student
I was working on an intricate pendant with many, many hard solders. I
fluxed, soldered, pickled, fluxed, soldered, pickled, just like I was
supposed to. Getting ready to polish it, every joint along this one
structural “spine” element failed. Upon examination the failed seam
appeared to be crystalized. We surmised, correctly I think, that
repeated heatings and picklings changed the chemistry and physical
structure of the solder, leaving it brittle.
All of the failed seams were soldered and held up for quite a while.
What I learned from this was the the flux, solder, pickle litany was
not really right. I never pickle until the condition of the flux or
metal indicates that it is time to do so. Your eyes will always tell
you when the time is right. I believe that the pickle eats away at
the zinc in the solder leaving the alloy brittle and weak. Too many
unneccesassary heating/ pickling operations just aren’t great for the
project…
noel, this is also my profession,i work for a manufacturer and do it
all,also taught benchworkers and did not mean to upset anyone-but is
their a jeweler out their maybe even allen who still does not have
some small thing happen - that reminds him (welcome to the world of
jewelers)
Too many unneccesassary heating/ pickling operations just aren't
great for the project....
Happy holidays and this point brings up a question for me. I just
finished taking my first class at a local art center. One of the
projects I was working on was a fold-formed shape (Reuger fold?).
Anyway, I was told by the instructor to pickle after every
annealing. The reason given was that the dark color that develops on
the silver after each annealing (until that point where the piece is
essentially coated with fine silver) would become engrained (sp?) in
the piece after hammering. I didn’t test the theory as of yet, but I
am now curious about the whole hammer, anneal, pickle process. Is it
really necessary to pickle after each annealing? Leaving it out would
increase productivity greatly.
I have also been given 2 opinions on the use of brass vs. copper
tongs in the pickle. (I feel silly asking this one) I was told to use
copper tongs in the pickle and I have read that I should never do
this, only use brass. Which is correct…for the sake of the amount
of thinking time I have spent on this issue.
Thank you and aren’t you guys glad to be over that holiday rush?
I was told by the instructor to pickle after every annealing. I
have also been given 2 opinions on the use of brass vs. copper
tongs in the pickle.
Hi Kim, I’m sure you will get a torrent of opinion on this one.
I tend not to pickle very often in a fold-forming, certainly not
when the fold has been annealed and is still folded up-I don’t want
acid in the recesses which would splash out when forged again etc,
plus, as you say, it takes time. I’ve never seen a problem from doing
this. One might pickle, and brass brush with soapy water near the end
of a sequence. As well in a shop one works on several items at once
so you never have to stop moving unless you actually want to take a
break.
Secondly, brass, copper tongs, makes little difference in my mind.
Copper might avoid an occasional and rare problem with zinc (from the
brass) initiating an electrolytic plating -(Have I ever seen this
from brass tweeezers-no). In England I’ve seen brass tweezers used at
the bench frequently for pickle.
Sometimes I see pickle pots in schools labeled gold and silver only
and copper and brass only. I always find this funny, as there is no
reason to segregate the metals like that in an art school situation.
In Germany, where I trained the pickle pots for gold and silver were
actually made of thick copper, we would take a dipperful of sulfuric
acid and water, hold it over a giant foot pedal operated bunsen
burner and bring it to a boil in moments. Iron, steel, zinc in the
pickle is another story but even there myths abound. The reason for
any copper plating that occurs is you have made a battery by having
two appropriately different metals such as iron and silver in the
(plating solution) pickle at the same time. When you take the
tweezers out the current stops and the pickle goes back to normal.
Use copper or bamboo tongs with pickle. I have never heard of using
brass tongs in pickle, never even seen brass tongs. The big thing is
to not ever introduce steel into the pickle.
None of the tool catalogs I have offer pickle tongs in any metal
other than copper. It won’t contaminate the pickle, nor will the
pickle corrode it. On the other hand, brass will pit if left in
pickle. My advice? stay with the sure thing. Get copper tongs.
You also want to watch temperature in which you pickle. You never
want to toss your freshly soldered piece directly into the hot pickle
as the temperature change and the acid will begin burrowing little
pits. Let the joint cool a bit and then quench in water first, then
pickle.
The small amount of zinc in solders burns away each time you heat it
back up. Your joint actually does become harder and more brittle,
although I am not sure it is the pickle that does this. Different
companies make different solder alloys. My personal choice? Hoover
and Strong. They make an excellent solder.
For gold I would go with Otto Frei. Theirs works very well.
-k
Karen Christians
M E T A L W E R X
50 Guinan St.
Waltham, MA 02451
Ph. 781/891-3854 Fax 3857 http://www.metalwerx.com/
Jewelry/Metalarts School & Cooperative Studio
Is there any soldering in your fold forming process ? If not, there
shouldn’t be a problem w/ pickling. Just make sure that you
NEUTRALIZE the piece in a baking soda solution, and thoroughly DRY
it before continuing your hammering. You don’t want to rust your
steel tools.
With reference to your question of copper vs brass, either should
work. I’ve never seen a pair of brass tongs distributed
commercially. Copper is the standard metal used for this tool.
I am curious if Kelly Herd is related to Lola Herd. If so I would
like to know how she is doing. At one time I did Lola’s casting work.
Please contact me off list
The big thing is to not ever introduce steel into the pickle.
Actually, as long as the iron in the steel is not free to react (as
in stainless steel), you won’t have a problem. I have used stainless
steel tweezers in my pickle for many, many years.
Is there any soldering in your fold forming process ? If not, there
shouldn't be a problem w/ pickling. Just make sure that you
NEUTRALIZE the piece in a baking soda solution, and thoroughly DRY
it before continuing your hammering. You don't want to rust your
steel tools.
Just a reminder, ascorbic acid, vitamin c powder can be used as a
pickle I use it on charm bracelets when I am afraid something will
turn the charms pink, and also if you are afraid of a stone etching
from pickle: lapis, malachite, pearl, peridot, rhodochrosite.
I was told by the instructor to pickle after every annealing. I
have also been given 2 opinions on the use of brass vs. copper
tongs in the pickle.
I haven’t used tongs to remove items from the pickle pot in years. I
found a plastic container that fits in the pickle pot. It is tall
enough to have the edge stick above the pickle solution. I drilled
many holes in the container and place it in the pot. Soldered items
can be placed in the plastic container and remove easily by lifting
the container out of the pickle. The container containing the
soldered items can be rinsed under running water or dunked into a
large container of water.
The same container can be used to hold pieces that have been
oxidized. The container and items can be rinsed without having to
hold and rinse individual pieces.
Thank you Karen,…I think your comment bears further
investigation on this pickle/loss of solder strength thing. I agree
with you that solder does become slightly harder each time you heat
it. Makes sense also that a strong hot pickle would erode away any
surface zinc remaining and perhaps other materials in the solder. So
it might not be just the pickle but a combination of high soldering
heat and strong hot pickle that weakens the join… In our shop, we
always water quench first - to preclude splashing as much as anything
else - then into moderately warm pickle. Maybe there are other
benefits. Comments anyone?
Cheers from Don at The Charles Belle Studio in SOFL where simple
elegance IS fine jewelry!! dcdietz@comcast.ne