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Firescale with Argentium Sterling


#1

I have just finished 3 small pendants made with argentium
sterling… and all 3 have visible firescale. I did not think this
was possible!

I’m quite sure that the sheet was actually argentium; I bought it
from Rio Grande, and have always found them reliable. Also, the
problems I had with slumping while soldering a fourth piece were
different from my experiences with normal sterling. However, the
clear presence of firescale- in about the places I would normally
expect such- baffles me.

I have followed the usual directions for working with argentium. I
did not use flux or firescale preventative during the soldering
operations (except flux on the joints themselves); from what I’ve
read that’s not supposed to be necessary, but perhaps it is. I also
heat-hardened the pieces, again without firescale preventative, at
580F for an hour; the temperature may have gotten somewhat higher at
points, because my kiln tends to overshoot the target some.

Any ideas what’s going on? I love the idea of argentium, but the
supposed lack of firescale is a lot of its charm!

Amanda Fisher
now off to remove firescale again sigh


#2

Hi Amanda,

I have also had problems with some firescale on Argentium and the
only conclusion I can come to is that I am somehow contaminating the
metal either by using a firebrick that had sterling soldered on it,
or a buff that was used for another metal. Most of the time, I don’t
get firescale, but it has happened more than once. Could that
possibly be the explanation for you too?

Grace


#3

I have cast, fabricated and soldered hundreds of pieces using
Argentium 925, and I have NEVER seen firescale. The stuff is amazing!

Something is wrong somewhere.

The first place to look is your supplier. Rio Grande is very good,
but maybe they made a mistake and sent you normal sterling.

Jon


#4

Is it actual firescale or is it a black oxide? I have had pieces
turn black in areas and it either burns off the next time it is
heated or pickles off easily.

Michelle


#5
I have cast, fabricated and soldered hundreds of pieces using
Argentium 925, and I have NEVER seen firescale. The stuff is
amazing! Something is wrong somewhere. 

I’m afraid I have to second what Jon has said here: something is
definitely not right here.

I’ve heard this from a few other folks and it generally seems to
turn out to be a “process” issue. In other words something in the way
your metal was treated before you received it or in the treatment you
are giving it is causing it to behave abnormally.

I usually begin by asking a few basic questions:

  • Have you tried to reheat and pickle the metal? One of the great
    tests for a piece of Argentium Sterling (AS) vs Regular Sterling is
    that you simply heat it until the oxide goes away (thank you
    Cynthia).

  • Are you absolutely certain it’s firescale? Are you seeing
    sub-surface oxides you can’t get rid of without grinding OR is it
    simply surface oxides you’re having trouble pickling off?

  • Have you tried wiping the stuff off? I know this sounds goofy but
    in the early days I was getting carbon deposits on my AS because of
    the way I was doing things and it had me puzzled for a while. When I
    discovered it simply wiped off I knew that I needed to change my
    process a bit in order to keep the metal cleaner and thus avoided the
    carbonizing altogether.

I guess the message I’m trying to pass along here is that contrary
to what you may be thinking at the moment AS does work as many of
us here have demonstrated. It does exactly what it’s supposed to do
when you follow a few basic (now well documented) procedures.

If it’s not “working” for you then either there’s something amiss
with the metal you received (pretty unlikely but not impossible) or
there’s something in your processes that is causing the difficulties.
The solution is almost always to eliminate the troublesome step in
your processes. That may require a bit of experimentation on your
part.

Cheers,
Trevor F.
in The City of Light
Visit TouchMetal.com at http://www.touchmetal.com


#6

Hi Amanda,

I wonder whether you are using the term firescale correctly? Do you
mean that after working the metal, there is discoloration underneath
the surface (which is firescale)? Or, are you concerned by the way
that Argentium Silver, like traditional sterling silver, often has a
coppery look on the surface after the first heating and pickling? In
my experience, this copper is on the surface only, and disappears
after further heating and pickling, or mild surface abrasion, such
as with a scotchbrite pad or pumice. I certainly understand your
concern, and hope the problem can be figured out! Best wishes,

Cynthia Eid
http://www.cynthiaeid.com


#7

I’ve been using the Argentium sterling and am familiar with the
black oxide

  • which does burn off with subsequent heating or can easily be
    removed with bristle disks.

However, In some of my earliest pieces, I did notice what appeared
to be firescale - a mottled stain that wasn’t easily removed. This
seemed to be most common adjacent to the base of a bezel. At that
time I was using paste flux (Handy) which really facilitated the
solder flow. The paste fluxes in general had been recommended for use
with Argentium.

In my research on the use of Argentium I had read that “some” paste
fluxes could stain Argentium sterling. I concluded (right or wrong)
that Handy was one of the paste fluxes I’d read about though I was
unable to verify the brands from the literature.

I decided to use another recommended flux.

F Flux powder from Thessco in England was very highly regarded by
Trevor (see below) who went through quite some effort to obtain it
but when I found that buying the F Flux powder (500 grams) would run
$200 with shipping and courier charge to Phoenix I ordered the
My-T-Flux from Rio, as it had been well rated.

I haven’t seen the stain since I’ve been using My-T-Flux. (Knock on
wood, cross my fingers, hold my tongue just right) :slight_smile:

My thanks to Peter Johns for his development of this wonderful
metal.

Though I’m still learning about working in Argentium sterling, I
offer many thanks and much appreciation to the following for
considerable and support regarding its use:

Trevor: http://www.touchmetal.com/blog/argentium-blog.html
Cindy: http://www.cynthiaeid.com/argentium_1-5.html
Marty: http://argexp.blogspot.com

***ArgentiumSilver.com

And to the Orchid forum, Ganoksin, Hanuman, Charles and Ton and all
their support crew I owe a continuing debt of gratitude for making
such sharing possible.

Pam Chott
www.songofthephoenix.com


#8

When I tried precipitation hardening on Argentium silver, the piece
came out stained gray. I couldn’t remove this gray with pickle or
polish (sanding was not an option with granulation). Finally, I
burned it off with a torch.

This may be similar to an earlier post about removing gray stain
from a coil of AS wire where Cynthia Eid’s solution was to burn the
stain off.

It helps to coat the piece with liquid flux before heat hardening
but, all things considered, I couldn’t think of a good reason to put
the metal through this process in the first place.

I would like to know when others think precipitation hardening
should be done.

Nancy
www.psi-design.com


#9
Is it actual firescale or is it a black oxide? I have had pieces
turn black in areas and it either burns off the next time it is
heated or pickles off easily. 

This was definitely firescale. The pieces were soldered between 3-5
times each, and pickled after each heating. The oxides came off
readily- but the firescale I’m talking about survived polishing to a
high shine, with abrasives as well as tumbling (abrasives before and
after tumbling). It was definitely in the metal, not just on the
surface.

Thanks for your feedback!

Amanda


#10
The first place to look is your supplier. Rio Grande is very good,
but maybe they made a mistake and sent you normal sterling. 

I’m VERY sure that Rio did not send me regular sterling instead of
argentium. I’ve been working with sterling for 15+ years now, and
this stuff didn’t act like regular sterling- it slumped under heat
far more than regular sterling does, for instance, which is
consistent with argentium. Also the color changes etc. during and
after heating were more consistent with argentium than sterling.

That’s one of the reasons I’m so baffled- I’m completely confident
that this was argentium and Rio didn’t send me the wrong stuff… and
yet, there was that pesky firescale. Weird!

Thanks!
Amanda


#11

Hi Grace-

I have also had problems with some firescale on Argentium and the
only conclusion I can come to is that I am somehow contaminating
the metal either by using a firebrick that had sterling soldered on
it, or a buff that was used for another metal. Most of the time, I
don't get firescale, but it has happened more than once. Could that
possibly be the explanation for you too? 

Thanks for your input! I have to assume I’m contaminating it
somehow- I just don’t know how. I didn’t use any buffs on it before
heating, so that couldn’t have caused the firescale, and I soldered
it on a clean charcoal block, and the areas that got the firescale
were never in contact with the block anyway.

My best guess is the pickle- it’s clean, but it is the same pickle I
use for regular sterling. I’ve read different opinions on whether one
needs argentium-only pickle, but right now- after this- I’m thinking
maybe yes, one does.

Thanks again!
Amanda


#12

Hello all,

We are concerned and very curious as to why this is happening, and
we are working closely with Amanda to get this figured out. When I
receive any I will most assuredly share with the group.

By the way, thanks so much for all the great info shared, it is
invaluable.

One last note I’d like to pass along to the group. Rio has a
dedicated room only for Argentium raw material, this would make it
very difficult for us to mix stock.

Sincerely,

Thackeray Taylor
Rio Grande Technical Support
800-545-6566
505-839-3000 ex 13903
technicalsupport@tbg.riogrande.com


#13
My best guess is the pickle- it's clean, but it is the same pickle
I use for regular sterling. I've read different opinions on whether
one needs argentium-only pickle, but right now- after this- I'm
thinking maybe yes, one does. 

Yup, I’d say that could be (part of) it. It’s not a common problem
but it’s pretty easy to solve, as you’ve surmised.

There’s also been some talk of fluxes and that too can be an issue.
I’ve found Argentium Silver (AS) to react VERY differently to
various fluxes, far more so that you’d expect from experience with
regular sterling. Again the solution is pretty straightforward: find
one that works well for you and you’re set. :slight_smile: As Pam mentioned I’ve
had good success with Thessco F (a UK product) but My-T-Flux is more
readily available in the US, is easier to work with, and seems to
work very well.

Someone mentioned using flux while precip hardening: I know this is
old news but the general rule with AS is to allow it to react with
the atmosphere as much and whenever possible (at least after it’s
left the factory). Fluxing while precip hardening strikes me as both
a waste of flux and counterproductive to enhancing the tarnish
resistance of AS.

Cheers,
Trevor F.
in The City of Light
Visit TouchMetal.com at http://www.touchmetal.com


#14
 and I soldered it on a clean charcoal block.... 

I missed this the first time 'round but it could be important.
Generally speaking I’ve found that charcoal blocks and Argentium
Sterling (AS) don’t mix.

To make a long story short I’ve found that the AS behaved
unpredictably when heated on a charcoal block: sometimes no problems,
sometimes a lot of discoloration, sometimes it pickled nicely,
sometimes it didn’t. In the end I admitted that I didn’t know what
was going on – no, it wasn’t a dirty block, nor old block, nor dirty
metal issue – but I knew I didn’t need the hassle.

Save the charcoal blocks for regular sterling: IMHO AS neither needs
nor likes them.

Cheers,
Trevor F.
in The City of Light
Visit TouchMetal.com at http://www.touchmetal.com


#15

Interesting. So far I have done all of my Argentium work on a
compressed charcoal block. Soldering, fusing, granules. Haven’t seen
any problems yet. Maybe I am not looking close enough. I am also not
working with Argentium for every piece yet.

If anything, I have been concerned about the slight reducing
atmosphere created by the charcoal inhibiting the germanium oxide
formation. Can’t say that I have seen a problem. Just a concern.

When I use a flux, I use Stay-Sil flux…white paste. Need to get
some My-T-Flux to try out.

How is the My-T-Flux different from Battern’s?

When I teach a workshop, the students get a Soldieries pad to work
on. I do find that the pad works better if it has had a large flame
passed over the work surface before it is first used. Something about
the fresh surface does not let the piece of silver draw up into a
ball. I start everyone out by melting a square of 26 ga. Argentium
sheet into a ball. This lets them begin to see the color difference
as the metal heats up.

Bill Churlik
www.earthspeakarts.com


#16

I am having similar problems with my Argentium stock and have not
totally pinpointed the problem - just guessed that it is
contamination. I have purchased stock from several suppliers, mainly
Rio, but also Hoover and Strong and also G&S metals. I don’t keep
them separate so it is difficult to say which supplier’s stock is
getting firescale - however, I can say that not all the stock gets
firescale all the time if that is any clue. Also, I use Prips Flux,
mainly because I have a large supply of it - and I don’t understand
why that would be the source of the problem?? - I’ll have to pay
closer attention to the source of the material when it happens. I am
also curious - just how easily does Argentium get contaminated - I
use dedicated firebrick and buffs, but I certainly haven’t replaced
all my tools.

Grace


#17

I think the problem may lie with using a charcoal soldering block. A
metallurgist acquaintance agrees, and says:

      When soldering on a charcoal block it is entirely
      possible that a reducing atmosphere of carbon monoxide will
      be produced close to the surface of the charcoal block as it
      is heated. (This is the principle behind using graphite or
      charcoal on the top of molten silver to prevent excess oxygen
      entering the molten metal.) 
      The presence of this reducing atmosphere would inhibit
      the formation of the protective germanium oxide layer during
      the soldering operation and also has the potential to reduce
      any germanium oxide already present on the surface back to
      germanium.

This makes sense to me, since I understand that the reason that
sterling silver gets firescale is that silver is one of the few
metals that allows oxygen to penetrate below the surface. Argentium
Silver does not get firescale is because the germanium oxide on the
surface does not let oxygen through. So, if the charcoal prevents
germanium oxide from forming, then the oxygen can get inside the
metal, to create Cu2O, cuprous oxide, known as firescale.

I have not personally used charcoal with Argentium. I use Solderite
boards for soldering; they reflect heat very well. I use ceramic
boards, such as Silquar, for fusing; these don’t reflect heat as well
as Solderite boards, but the Solderite boards break down under the
higher heat of fusing. I also have used honeycomb ceramic blocks and
ceramic blocks made for Platinum for fusing.

In addition, it seems that paste fluxes may cause firescale. I
certainly have seen this happening on traditional sterling, which is
part of why I got out of the habit of using paste flux for soldering.
(I know–it does not seem to make sense, but it is true! When I
worked in traditional sterling, I noticed that the firescale pattern
matched the pattern of the paste flux application.) I have, however,
been using paste flux as a temperature indicator for annealing. I
have not noticed a problem with thatI’m not sure whether it is
because annealing is at a lower temperature, or whether I simply did
not realize. I’m going to need to check on that! I use Rio Grande’s
My-T-Flux for soldering and fusing.

Yours in the fight to eradicate firescale,
Cynthia Eid
Www.cynthiaeid.com


#18

Hello all,

We are concerned and very curious as to why this is happening, and I
was wondering if Cynthia Eid had comments on two issues regarding
working with Argentium:

  1. The issue of what flux works best
  2. The issue of firescale

I must say that Cynthia Eid is one who knows her material and her
word is quite reliable.

John


#19

I haven’t used AS, but doesn’t it need to have oxygen present to
react with the germanium? in that case, during soldering temps the
reducing atmosphere of the charcoal (needed for sterling) would
interfere with AS’s ability to keep from firescale.

just pondering away on the keyboard… enjoying spring in Montana.

Frank A. Finley
Salish Silver
Handmade Indian Jewelry


#20

Trevor,

This evening I put several test pieces in the kiln to heat harden.
On one granulated earring I put flux on one half to see if it would
help. It didn’t. So, you are correct, it is a waste of time. The two
items that had granulation both turned dark smoky gray around and
between the granules. Other items, including some scraps of AS
silver and some fused with larger decorations did not discolor at
all. So, I don’t know why this happens. I wouldn’t call it firescale
but it is an exasperating gray stain.

Nancy
www.psi-design.com