Firescale

I find it harder to polish silver to areally high lustre than
gold. Any tips?

Have you tried ZAM?

 When finished soldering, the piece goes directly into the
pickel from the soldering board....HOT.

Hi John

This was an absolute “don’t do” when I was an apprentice.
Quenching the piece in pickle will result in the acid being
sucked into micro-pores in the metal by low pressure (in fact
its forced in by the normal pressure, I know), and it cannot be
removed from there, not even by neutralizing. When the piece
comes into contact with sweat, the acid can again become active,
resulting in green stain on the skin or some allergic reaction.
And, besides splashing acid all around, quenching may be cause
of warping of your workpiece. Reminds me of a colleague of mine.
In the master examination, she quenched her piece (in water)
after soldering a frame of square wire onto a medaillon lid, I
think she was much too upset by all the stress to give it a
think. The whole thing warped badly, and she had a hard time to
get it right, nearly failed.

regards, Markus

find it harder to polish silver to areally high lustre than
gold.  Any tips?

Have you polished through the firescale (pinkish) layer? If not
try some bobbing compound or tripoli on a brush or wheel and be
aggressive. Firescale is really stubborn, but the luster that
results is worth it to me when I break through the layer. I do
this on my high end pieces only, because it wouldn’t be
economically feasable to do it on my production work, which I
throw in my tumbler.

Wendy Newman

   I use the dark stiff ones with the bobbing compound, and I
wish I had something a little less stiff I could use with the
tripoli afterwards.  I will defineately give them a try.  Rio's
latest catalog has a 3/4" medium brush listed which isn't
shown.  I wonder if they are the same?

Sharon, Thanks for pointing that out! I have to make a rio tools
order Tues and will order a package and let you know if they are
the same. I think the ones I get from Tidewater are made by
Dixcell (sp?).

Wendy Newman

 When finished soldering, the piece goes directly into the
pickel from the soldering board....HOT.
Quenching the piece in pickle will result in the acid being
sucked into micro-pores in the metal by low pressure (in fact
its forced in by the normal pressure, I know), and it cannot be
removed from there, not even by neutralizing.

G’day: Markus, I do see the truth in your comment, and I sit
thoroughly corrected. Despite having done this for ages. I will
stop the practice, although I’ve not had any complaints from
anyone, nor seeing warping and not had lace clothing as a result
of acid splash (I lifted the lid of the pot only far enough to
drop the work in). But I promise not to do it again. Thanks, and
cheers,

        /\
       / /    John Burgess, 
      / /
     / //\    @John_Burgess2
    / / \ \
   / (___) \
  (_________)

Letting the just soldered piece air cool a bit, retains some of
the hardness of the silver. Dropping red hot silver into pickle
anneals it . Warm work, hot pickle in a crock-pot.

Bill
Ginkgo Designs
@WILLIAM_I_EISENBERG

G’day: Markus, I do see the truth in your comment, and I sit
thoroughly corrected. Despite having done this for ages. I will
stop the practice, although I’ve not had any complaints from
anyone, nor seeing warping and not had lace clothing as a result
of acid splash (I lifted the lid of the pot only far enough to
drop the work in). But I promise not to do it again. Thanks, and
cheers,

Hum…

Now I really do not know what to think. Cynthia has been doing
this for YEARS and has never had returns or other problems. The
idea of micro pores sounds possible but somehow does not seem
just right. As to warpage, might the lid in question have been
warped by uneven heating BEFORE it went into the “water”?
Cynthias art metal instructor stated (many years ago) that some
of these “techniques” get started for the darndest of reasons,
but not necessarily for the stated reason (hidden agendas).
Reminds me of some of the old wine making books that I have (for
home winemakers) that state the yeast must be spread on a piece
of crustless toast and floated on the juice to start
fermentation. I like toast with my grare preserves, jam or
jelly, but I really don’t care for it in my wine. I made wine
for many years and never found it necessy to proceed with this
“must do” operation. Could this be another one??

Before I change my process I think I will have to get more info,
but I thank you very much for your thoughts on this subject. We
also go by the statement here “If it works for you and your happy
with it, keep doing it.” There are a zillion ways to skin a
___________ (what ever you want to put in here!!).

John and Cynthia/MidLife Crisis Enterprises
Maiden Metals/C. T. Designs/ Bloomin’ Wax Works. etc. No one is
guaranteed happiness. Life just

PO BX 44, Philo, Ca 95466
gives each person time and space. It is
Ph 707-895-2635 FAX 707-895-9332 up to us to
fill it with joy.

I thought, also, that it was kind of curious, saying not to
quench in hot pickle. Every silversmith I know and all the books
say to do so. Of course you don’t throw it in until the red heat
disappears, one tip. I would think the polishing process, if any
acid actually IS in the metal, would remove the thin layer. I
would think also a long soak in baking soda would reach anything
that would be exposed to skin, and by the way human skin is a
slightly acid medium itself…OK, John Burgess’s turn :slight_smile:
Dave

http://www.opendoor.com/stephensdesign/crystalguy.html
Crystalguy Art Jewelry, Magical Art Jewelry for the Enlightened Mind
Kickass Websites for the Corporate World
http://www.opendoor.com/stephensdesign

    I thought, also, that it was kind of curious, saying not
to quench in hot pickle. Every silversmith I know and all the
books say to do so. Of course you don't throw it in until the
red heat disappears,........OK, John Burgess's turn :-)  

G’day: Well. I know that I promised “not to do it again” but I
must have been in an unusual placatory (good word, eh?) mood that
day, because I have since regretted it. Another case of ‘put
brain into gear before hitting send button’ Indeed, I have ‘done
it again’ because I came to the same conclusions as Dave, and
only this morning hot-quenched in my usual 10% sulphuric acid,
followed by a stay in bicarb solution whilst I had a homebrew, it
being that time. Seriously though, I think that a hot quench
could get the acid into tiny cavities, if there is any in the
work. If there was air in the cavity, high heat would drive it
out, and the sharp quench would cause the vacuum in the cavity to
be filled with acid when the stuff rushed in to fill the space.
However, that said, I think that the microscopic amount of acid
shouldn’t become much of a problem. If folk are worried, then a
heat-cool cycle in the bicarbonate should fix it. Finally, I
know that the fatty acids in all human sweat tend to go for
metals like copper, possibly accounting for the slight greenish
tinge one or two have reported as having been seen on necks and
wrists, etc. But I am at a loss to understand how enough to be
visible could come from sterling or 14ct gold. So there you are
Dave, my NZ$0.02 (x 1.552 to bring it to $US) Cheers.

        /\
       / /    John Burgess, 
      / /
     / //\    @John_Burgess2
    / / \ \
   / (___) \
  (_________)
I thought, also, that it was kind of curious, saying not to
quench in hot pickle. Every silversmith I know and all the books
say to do so. Of course you don't throw it in until the red heat
disappears, one tip. I would think the polishing process, if any
acid actually IS in the metal, would remove the thin layer. I
would think also a long soak in baking soda would reach anything
that would be exposed to skin, and by the way human skin is a
slightly acid medium itself........OK, John Burgess's turn :-)
Dave

Hmmm… I was taught to quench in water first and then pickle.
Curious. I thought it was because of the possibility of splashing
hot pickle on your skin.

Kathie

I was taught that you quench fine silver in water and then
pickle after soldering and that you must air cool sterling and
then pickle…

John. In some rare cases people do react to the copper in
sterling, I am one of those luck individuals. It only happens
when I get hot and sweaty and is not a big problem. I have never
had a problem with any gold alloy.

There’s my $0.03104 worth (american)
Jim Loveland

I may be totally off my rocker here, but, on the subject of
firescale on silver…

I don’t work with silver much, but in one of my brain dead
moments, I quenched a silver piece in the baking soda solution by
mistake. I rinsed it off, pickeled it for a minute or two, wiped
it off, a quick buff and I was done…no firescale. There had
only been a single soldering operation on the piece, so that may
explain the lack of firescale, but I was wondering if someone who
does a lot of silver work might try quenching in the baking soda
to see if that helps the problem at all. I had used a boric
acid/alcohol firecoat. I can’t believe this will really work,
but maybe it’s worth a try.

Sharon

I may be totally off my rocker here, but, on the subject of
firescale on silver... I don't work with silver much, but in
one of my brain dead moments, I quenched a silver piece in the
baking soda solution by mistake.  I rinsed it off, pickeled it
for a minute or two, wiped it off, a quick buff and I was
done...no firescale.  There had only been a single soldering
operation on the piece, so that may explain the lack of
firescale, but I was wondering if someone who does a lot of
silver work might try quenching in the baking soda to see if
that helps the problem at all.  I had used a boric acid/alcohol
firecoat.  I can't believe this will really work, but maybe
it's worth a try.

Hmmmmm, very interesting! I’ll have to try adding some baking
soda to my quenching water and see what happens (I solder silver
a LOT!) ; )

I have followed this thread as well as the subject of fire scale
for some time, have read the subject several times and work with
silver 65 percent of the time. My current understanding is that
fire scale IS NOT the black appearance on silver after casting.
That it is in fact a black color imbedded in silver item which
cannot be removed by a light abrasive or polishing… If this is
true, then I’m finally doing something correct because I have
never had the problem!!!

I puddle the silver, pour Borax on the puddle, lightly swirl the
mixture, pour ASAP. Don’t know if this has any bearing but …
that’s it! . . The way I was taught??? Think the Borax pulls the
"floating crud(technical term)" on the silver puddle surface to
the bottom of the casting container.

Jim

I haven’t been following this thread closely enough, but has anyone
suggested the use of bright-dip for getting rid of firescale (which I
take to be a combination of cuprous and cupric oxides)? Admittedly,
I mainly work with base metals (copper, red brass, nickel-silver),
but a few seconds in nitric acid which has been diluted by half (you
all know how to do that safely) gets rid of all firescale and
produces a wonderfully cleaned, slightly matte, surface.

Nitric acid is cheap (get the industrial grade, not the reagent
grade) – about $5 a gallon, and if you work carefully and slowly
with it, it’s not a problem (I’ve done this for 20 years), and it
lasts a long time.

It will not remove the black, glassy residue from fused flux (Sparex
will do that).

I’m probably carrying coals to Newcastle, but I really enjoy the
Orchid List for its discussion of alternatives!

Judy Bjorkman
@JLBjorkman

I have read about the use of 50% nitric acid and 50% water dipping
and scratchbrusing as a means of removing firescale. However I am
not sure what scratchbrusing is. I have been told that it is the
use of pumice and brushing.

I would apreciate a response from anyone who has experience in
removing firescale with this technique.

Art Ellis

The best way to remove firescale, is to diminish its effect in the
beginning. If you build up a solid layer of fine silver on the
surface, your pieces won’t tarnish very much and you can avoid
firescale pretty much all together. This process is called
“depletion” and can be done with gold as well as silver. Another
helpful point is the flux. I use a fluoride free paste flux called
Superior Six which I found on the SAS website. This flux coats the
silver and does not break down in higher temperatures.

Depletion method:

  1. paint a small line on your metal with your flux, no I don’t
    cover the whole thing

  2. anneal your metal until the flux has melted into a flat smooth
    line

  3. cool the metal, don’t quench, rinse and pickle

  4. brass brush with a small amount of Dawn or some degreasing soap

  5. rinse and repeat this method 7 to 10 times

  6. watch your flux very carefully on the 3rd time around, this will
    be your only temperature indicator

  7. you will notice your sterling will go black in the beginning and
    then a kind of dead white later on. That black is the copper moving
    up to the surface and burning out. This is the fine silver buildup.

For roller embossing, don’t brass brush on the last cycle. Emboss
on the deadwhite or pickle surface. After roller imprinting, you can
brass brush if you want. I do all my construction at this point.
When the piece is finished, the final brass brushed surface is
simply luminous and very strong.

Note on brass brushing, brush LIGHTLY. Your brass brush is a
POLISHER only, NOT A SCRUB BRUSH! If you brush too strong, you will
work harden your nice brass brush. My favorite is a plastic handle
with a slight bend. This enables you to get into those little
crevices.

You won’t need acid, filing or sanding with this method. The
annealing can be done in a kiln set about 1200 degrees. Anneal for
about 5 minutes for the first round and 2 minutes each for the next
six.

Karen Christians
M E T A L W E R X
10 Walnut St.
Woburn, MA 01801
Phone:781/937-3532
Fax: 781/937-3955
http://www.metalwerx.com/
Accredited Jewelry Instruction

The best way to cure firescale, that purple coat, that coat when
soldering is to prevent it from occuring. There is a fire coat
preventative flux on the market. It is formulated to prevent fire
coat. When properly used there is no fire coat. You can pre-polish
your work before soldering on additional items. Its called
cupronil.

I have a procedure that prevents firescale when you vacuum cast. If
you are interested in this simple no cost process that prevents
firescale when casting contact me. I will send you a paper for
free. The process produces a reducing atmosphere around the mold
while it is cooling before quenching. Reducing atmosphere, no
firescale. I don’t pickle my castings after quenching. Just polish
and solder on findings. Saves a lot of time and headaches.

Later
Lee

 The best way to remove firescale, is to diminish its effect in
the beginning. 

Karen, For those having chronic firescale problems, this advise is
the best Holiday gift they could receive. People are always asking
me to show them shortcuts for every technique…I tell they to
simply do it right the FIRST time. I would also add to your advise
that, if you are using a gas/oxygen torch, back off on the amount of
oxygen that you use in your flame. It should be a neutral flame, not
a hot, hissing, oxidizing flame. That type of flame has more oxygen
than the fuel can use, and the extra oxygen will eagerly combine
with the copper in your alloy to form cupric oxide: AKA firescale.
When you are annealing, with the intention of building a surface
layer of fine silver or gold, you want a THIN layer of oxide that
you can remove the copper from in the pickle. Don’t get carried away
here…I have seen beginners create an oxide layer so thick that it
goes completely through the metal. Work slowly, in thin layers, and
do this many times.

This technique does work for production as well as one-of-a-kind
pieces. Once you get a system in place, it is not as labor-intensive
as you might think. I use a magnetic finisher to burnish between
annealing when I have a lot of small parts to process, but I still
like the soft brass brush for sheet. When using this technique on
castings, remember that many alloys contain antioxidants to inhibit
the formation of firescale. Personally, I prefer the alloys that
will oxidize, so I can bring up a good layer of fine metal to the
surface. I work mostly in 18k yellow, and the result is a dark,
lustrous surface that looks like 24k.

I wish everyone here a Happy Holiday, and a New Year filled with
Peace and Prosperity!

Doug Zaruba