Fire scale prevention

Jewelry Discussion
1

Fire scale is the scourge for anyone working with sterling silver.
How many of us old fogies have abraded away part of our design while
trying to remove fire scale. Or abraded unwanted grooves in the
design while trying to remove fire scale. Or burned our fingers while
holding a piece while using tripoli to remove fire scale. I once had
a very hot ring I was trying to remove fire scale from flip out of a
ring clamp and land on my arm. That was no fun.

All that changed in 1975 when anti fire scale fluxes were developed.
Unfortunately there are many who still have fire scale problems
because they have not discovered anti fire scale fluxes.

Anti fire scale fluxes DO work to prevent fire scale when soldering.
However if you heat a piece for a long period of time while soldering
the flux will break down and fire scale will form. My guess is that
the fire scale prevention ability of anti fire scale fluxes is lost
during annealing because of the time the metal is held above around
1000 degrees.

I cast around 130 ounces during one of my casting days. There was a
time before the old bones got tired that I would vacuum cast twice a
month.

I originally designed all my cast items so that I could sand fire
scale away. But then Hallelujah, I stumbled on a way to prevent fire
scale when vacuum casting. Now I can cast any shape fire scale free.

That allows me to create sculptures and cast them in sterling
silver.

I do have some interest in anti fire scale fluxes. I produce
Cupronil. My point is there are many anti fire scale fluxes on the
market. Use one when soldering. The time in polishing will be
greatly reduced.

Lee Epperson

2 
My point is there are many anti fire scale fluxes on the market.
Use one when soldering. The time in polishing will be greatly
reduced.

I have been trying out various fluxes and ways of working. I bought
Firescoff and was excited about it at first, but my enthusiasm has
dimmed-- it takes a couple-three bucks-worth of it per jewelry item,
and the results are not all that I had hoped.

Recently, I have tried spraying a heavy coating on My T Flux (from
Rio) on pieces after heating, and, though it makes a glazed mess of
my soldering pad, it seems to be doing the job. I’m working on
pieces with quite large, irregular-shaped bezels, which are always a
challenge to solder (sometimes it takes several tries to eliminate
all gaps, depending on how the Goddess likes me that day) and four
to six other soldering operations, so it I can get one of these done
without it being covered in firescale, I consider it a major
triumph. Maybe I’ll try Cupronil next.

Noel

3

Noel -

Are you pickling between soldering operations?? I am doing the same
sort of thing you describe, with similar potential problems. I am
using Prips flux (homemade) but I apply it to all sides at the
beginning and quench in water, then re-apply. I pickle thoroughly at
the end only.

The prips builds up on the piece and is not removed by the water
quench. It is very effective for me as I am only getting light
firescale (if any) easily removed with polishing.

Hope this helps as your problems as several of your suggestions have
helped with mine.

Debby

4

Noel,

Maybe I'll try Cupronil next.

I’d suggest trying it. It isn’t expensive and it works. I discovered
the product a few years ago. Like it so much that I’ve given to
friends…

Lee has waived his flag on the product yet the question is
continually asked.

Jerry

5

Noel,

I am using pripps same large bezel problems this is my first time
with it and it seems to be working very well so go for the cuprinal
its a plan lol

Teri
Silver & Cameo Heritage Jewelry
www.corneliusspick.com

6 
I have tried spraying a heavy coating on My T Flux on pieces after
heating, and, though it makes a glazed mess of my soldering pad

My-T-Flux is a poor choice for this use Cupronil or Stop-Ox or prips.
Use that air compressor you got for the air brush. get a Badger
bad250-4 spray gun it will hold 4 oz of flux it is a very basic
device that is easy to clean and will not clog easily and is

cheap Badger 250-4 Mini Spray Set Airbrush and Airbrush Set #250-4.

Set up a spray area in or next to your soldering area where you can
heat the work and flux it without spraying your soldering surface. I
use a 12" square piece of galvanized sheet metal to place the work
on while I warm it. I spray the work then transfer it to the
soldering surface for soldering. At the end of the week or earlier if
necessary I put the sheet metal in warm water to soak off all the
over spray and dry it and it is ready for use again.

I know <> feels spraying flux with air is “over the top” but I dont
have to deal with much if any firescale when the work is fluxed in
this fashion.

Jim

James Binnion
@James_Binnion
James Binnion Metal Arts

360-756-6550

7

Noel,

I use Prip’s Flux!!! I love it…although I did not make mine, like
Susan. I purchased mine from Contenti (Grobet makes it). See sight
below!

http://www.contenti.com/products/soldering/510-824.html

It does bubble somewhat…and from Susan’s post it sounds like maybe
that is the point of annealtion (ha, ha,…is that a word??:-)) I
assumed I was just being impatient and not letting it dry enough.
For annealing I just wing it, or do the Sharpie trick. Maybe Susan
(or someone) can expand on her comments…I would love to know if it
bubbles at a certain temp.

Thanks,
Aimee Domash

8

I have to jump in here. I have been using United Precious Metals
Master 88 alloy for silver castings for years and I DO NOT get fire
scale. I mill my own stock from the buttons and use boric acid and
alcohol (the same as for gold) for a flux. I use hard, medium and
easy solders. I DO NOT get fire scale with this alloy. The Master 88
alloy is the only reason I will work in silver at all. I have left
finished pieces and milled stock in the open air lying on my bench
for months (up to 10 or 1) at a time and never had tarnish problems.
Makes for easy clean up when I get goods back from the gallery.
Master 88 solders like regular sterling, mills well and I even use
it for chase and reposse. I haven’t tried raising it yet but I
forsee no problems. This stuff is a low ox wonder. You should order
an ounce and try it for yourselfs. Kiss your firescale problems good
bye.

1-800-999-fine (usual disclimer goes here)

Frank Goss

9 
Are you pickling between soldering operations??

In the pieces I described, sadly, I mostly do, because I can’t tell
whether there are gaps in the bezel-to-backing seam with the
built-up flux all over it. Any solution to that?

I haven’t broken down and made prips so far… I probably should.

Noel

10

I have a friend who works in the Tiffany’s studios and makes their
large chased pieces. She says they spray absolutely everything that
is exposed before annealing or soldering to prevent firescale. I was
taught this way and very rarely, if ever, have firescale. My training
was in a handwrought jewelry workshop and spraying was the way taught
due to speed and efficiency, I guess.

I work primarily in argentium now - not for the anti-firescale
property, which is a BONUS, but the outstanding silver color and
workability.

Susan

11 
Maybe I'll try Cupronil next.

I’ve used Cupronil (spraying or painting it on) for a couple of
years and find that it does a good job,

Although, I too struggle with sodering large bezels and doing
several soldering steps on each piece. Sometimes I do have fire scale
on the back of the piece - probably because I’ve gotten the thing too
hot trying to fill in gaps between the bezel and the back plate.

Soldering large bezels is another subject I know - I love Argentium
because of the no fire scale among other things but have given up on
it for large stones. The solder just will not flow all the way around

  • I end up with horrendous piles of solder, melted bezels from
    heating from the top (heating from the bottom results in too much
    sag). I’ve tried all the different solders recommended and most
    recently tried jel-flux. I have an order in for the new argentium
    paste solder but it is on back order. I also anneal the back plate.
    If any one has any other suggestions I would be most grateful.

Thanks,
Jan

12

Cupronil, which i have used since its production began in the early
seventies ( well, it was the seventies…who can remember anything
exactly as it wasback then…!) has been a consistent, excellent
performer as a firescale preventative and all around great flux
product- particularly on silver work with many solder operations
involved to fabricate a single piece…It has remained reasonable,
affordable and is produced by an extremely reliable and well run
business based on customer service and producing a top-quality
product; rather than investing a fortune in advertising experience
and word-of-mouth or passed down traditions are responsible for the
continued consistency, reliability and availability of Cupronil.

It outperforms firescoff in both reliability, cost, ease of
application and mechanism for delivery and other features ( like,
and i hate to even type this - but toxicity…as firescoff has
questionable aquatic effects not thoroughly researched as yet) that
make it an essential consumable for my bench, and hence, my
recommendation that everyone make it an essential on theirs as
well…You will never be disappointed nor will you have to use an
airbrush to apply it!

It is available in any size that suits your needs from a 4 oz. spray
in unbreakable plastic to a gallon or larger if you have a
manufacturing concern that is pumping fluids to a multi-bench set
up…

R.E.Rourke

13 
In the pieces I described, sadly, I mostly do, because I can't
tell whether there are gaps in the bezel-to-backing seam with the
built-up flux all over it

Yeah, I can see that. Usually I take forceps and try to move the
bezel side-to side if I suspect a gap. Perhaps Prips doesn’t block
gaps as effectively as what you are using?

If so, then you have little alternative to pickling but I suspect
that, if you effectively re-coat the piece again you should have
sufficient protection.

Debby

14 
In the pieces I described, sadly, I mostly do, because I can't tell
whether there are gaps in the bezel-to-backing seam with the
built-up flux all over it. Any solution to that?

Hot water! While the pickle does speed up the dissolving of the flux
hot water will dissolve most flux that has not been seriously
depleted (over heated, or too long at heat) I also find that a
little baking soda in the water will speed the dissolving of the
flux.

James Binnion
@James_Binnion
James Binnion Metal Arts

360-756-6550

15 
Soldering large bezels is another subject I know - I love Argentium
because of the no fire scale among other things but have given up
on it for large stones. The solder just will not flow all the way
around - I end up with horrendous piles of solder, melted bezels
from heating from the top (heating from the bottom results in too
much sag). I've tried all the different solders recommended and
most recently tried jel-flux. I have an order in for the new
argentium paste solder but it is on back order. I also anneal the
back plate. If any one has any other suggestions I would be most
grateful.

I am going to guess you need a bigger flame and a cooler flame.
Large pieces with long seams are the trickiest to do. If you do not
have the whole piece at the flow temperature you are going to run
into these problems. This is where the compressed air natural gas
torch really shines. I have a tip that produces a flame 2 inches in
diameter and 10 inches long but soft and cool so you will not
instantly melt the work and you will not over oxidize the flux. It
is perfect for gently heating the whole piece to soldering
temperature and flowing long seams.

James Binnion
@James_Binnion
James Binnion Metal Arts

360-756-6550

16 
Sometimes I do have fire scale on the back of the piece - probably
because I've gotten the thing too hot trying to fill in gaps
between the bezel and the back plate.

Actually, I think it is a matter of amount of time you have heated
the piece as opposed to how hot you got it. I find that the more time
spent soldering on a piece the more firescale you end up with. My
designs are basic and simple so getting rid of firescale is a matter
of first pre-polishing the piece with a 3" 3M blue brush wheel (I
think is 400 grit) then buffing with bobbing compound, then Zam to
finish polish. I generally go back and forth between the bobbing
compound and the Zam wheel.

Rick Copeland
Silversmith and Lapidary Artisan
Rocky Mountain Wonders
Colorado Springs, Colorado
http://rockymountainwonders.com

17

Noel,

I try not to pickle too much, especially if it it has hollow spaces
that might possibly trap pickle in an enclosed space later. If I
lightly spray Prip’s as the metal is warming and get the powder coat
finish on the surface of the metal, then there is visibility enough
to see the fillet of solder jet around the bezel base. If I need to I
will pickle it. I keep a bowl of clean water with a little bit of
baking soda in the water to neutralize the pickle. I don’t know if
that is good or not but just a sprinkle of soda in the water can’t
hurt, I think, but I don’t know for sure.

~Susan
Keeping cool in the blazin’ hot Nashville heat.

18

I solder large bezels on buckles. I use 18 gauge sheet cut 1/8 inch
wide for my bezels then epoxy the stones in place. I like the look
of a heaver bezel. The heavier bezel can be made interesting by using
a cut off disc in a hand piece to cut vertical grooves in the bezel.

I pre polish the piece before soldering.

I cover the entire piece with Cupronil each time I solder. I quench
and pickle the piece after each solder step.

Anti fire scale fluxes do not promote good solder flow. I find it
best to use a small amount of Handy Paste flux on all joints. Too
much Paste flux will flow when heated and remove the Cupronil from
around the joint and cause fire scale to form.

I lay the piece to be covered with Cupronil on a fire brick that I
use only for the purpose of coating the item with anti fire scale
flux.

I wire solder all large bezels. I find I have no problem seeing
where the solder has not flowed to close up a joint. I can close
these areas by applying the wire solder with the correct amount of
heat.

I manufacture Cupronil. All the anti fire scale fluxes work to some
degree. My suggestion is to never solder a sterling silver piece
without first covering it with the anti fire scale flux of your
choice.

Fire scale can be eliminated from the face of the earth if proper
care is used when soldering and vacuum casting.

Lee Epperson

19

Jan…my you are having some problems aren’t you?

My first advice is…definately use a protective flux when heating
sterling silver. Whether you use cupronil or Prips or whatever, use a
protective flux. Some old timers (I guess I would qualify for that)
swear you do not need to do so but I have been using it for going on
35 years and will continue to do so. Is it necessary on wire? Not
really as there is not enough visible surface to see it. Is it
necessary on fine silver bezels? Probably not…but I use it on
everything and make sure my students do too!!! Does it completely
preclude firescale? Nope…but it does a pretty good job and
certaily makes polishing a lot simpler.

Re soldering large bezels. By large…what do you mean? I solder all
my bezels up to 30x22mm holding them in front of me in tweezers and
heating them first from the back and then angeling the torch along
the sides. This gives a perfect join 95-99% of the time. (Now and
then I goof up :slight_smile:

When they get over that size up to some real whoopers…I use a
bridge. Not a soldering stand…those things are huge heat sinks and
usually take 2 to 3 torches to get any heat into your piece. Instead,
use two soldering bricks (I use magesia blocks) placed on a firesafe
surface angled out at approx 45 deg. Place a medium weight screen
over them and your piece to be soldered on top of the screen near the
front edge. Heat from underneath keeping the torch flame under
control so the heat goes into the base plate evenly. Move the flame
in a circular fashion then, as it heats up, concentrate your heat at
the rear till the solder flows, then move it slowly completely around
until all the solder flows. Try to keep the flame on the outside edge
of the bottom to draw the solder under the bezel and towards the
flame.

A couple of tips to get ready for this procedure. Before laying the
bezel on the back plate, be sure to sand the bottom of the bezel 100%
flat. Be sure the base plate is 100% flat and sand both sides
lightly. Use protective flux on both sides. After laying the bezel
on, add some cleaning flux such as Batterns, or some such, only on
the inside of the join. Lay in as few solder snippets as
possible…i.e. on a 30x22mm I use only 4 smsall size snippets
placing them 12:00, 3:00, 6:00 and 9:00 (or north, south, east and
west). On larger pieces you may want to add one more on each side.
Thats all you use. If you miss a spot, you can add a small amount
later but that is rarely necessary.

If you do miss a spot…hold the piece in front of you in a pair of
long tweezers. Have one tang over the bezel and one under the
backplate at the open spot. DO NOT SQUEEZE…imply hold it up. Heat
around the bottom and then concentrate directly under the tweezers.
As the metal heats up it will come together and the solder will
immediately flow. Don’t overheat but don’t take too long to heat it
either as strange things can happen.

Try it…it works…all my students learn to do that and normally by
their second bezel they always complete the job the first time.

By the way…I always pickle after each soldering job, unless I’m
doing something such as multiple prongs on a bearing or some such
thing. This allows me to assess my success (or failure) and to do any
clean up before laying on the next piece. Never had any problem with
multiple pickleings ruining my solder joins. If done right, they are
so small and thin, the pickle can’t penetrate or otherwise effect the
joins.

Good luck and cheers from Don at The Charles Belle Studio in SOFL where
simple elegance IS fine jewelry!

20

Firestain problems should be a thing of the past if you use
Argentium silver in the US and Brilliante silver in the UK. I have
tried Brilliante silver and firestain is greatly reduced.

Richard