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Flux before annealing?


#1

I’ve been making rings from sterling silver strip. I need to anneal
the strip at least once. I’ve read that you should flux the strip
before annealing (with a torch), but I’ve also read some
instructions that leave this out? What is recommended?

Thanks!
Leanne
Leanne Elliott Soden


#2

Anneal sterling silver naked - it’s better all around. Gold should
have a boric acid dip any time it’s heated to any real heat, but
silver doesn’t need it. Annealing temperature is way below the temp.
at which flux has any benefit. It’s just a waste of flux, and if the
flux does melt, you are way too hot.

http://www.donivanandmaggiora.com


#3

The purpose of this is to minimise fire stain by stopping the oxygen
in the air from oxidising the copper in the sterling silver. There
are propriety products available, Argotect is the one I use, but
flux also works - after all, its purpose in soldering is to prevent
oxidisation of the joint.

Regards, Gary Wooding


#4

If you want to avoid firescale on sterling you must always coat the
whole surface with flux like Prips, Cupronil or Stop-OX prior to
heating to anneal or solder.

James Binnion
@James_Binnion
James Binnion Metal Arts


360-756-6550


#5
Anneal sterling silver naked - it's better all around. 

Shouldn’t you at least wear a leather apron? ; )

Elaine


#6
Anneal sterling silver naked - it's better all around. Gold should
have a boric acid dip any time it's heated to any real heat, but
silver doesn't need it. Annealing temperature is way below the
>temp. at which flux has any benefit. It's just a waste of flux,
and if the flux does melt, you are way too hot. 

According to the technical data from Cookson Precious Metals, the
annealing temperature of Sterling Silver is 600C, MP of Ex-Easy
solder is 667-709C and Easy Flo flux 550-800C. You choose.

Regards, Gary Wooding


#7
Anneal sterling silver naked - it's better all around. 

I must disagree. I wish we could post images here, I have a few nice
micro-graphs that show the penetration of copper oxides in sterling
with successive heatings. Each time you heat sterling in air with no
protection the firestain layer gets deeper. Not only is it ugly but
it affects the structural integrity of the sterling. Eventually the
firestain will be all the way through thinner pieces. The metal will
loose its some of its ductility and become more brittle.

Gold should have a boric acid dip any time it's heated to any real
heat, but silver doesn't need it. Annealing temperature is way
below the temp. at which flux has any benefit. It's just a waste of
flux, and if the flux does melt, you are way too hot. 

Boric acid actually begins to from a sticky “liquid” at about
500-600 F even if it is not fluid till much higher tepertures and if
applied in a spray as in pripps flux or its relatives it will form a
protective blanket over the silver even if it is not actively
reducing the oxides at annealing temperatures.

Regards,

Jim

James Binnion
@James_Binnion
James Binnion Metal Arts


360-756-6550


#8

I like the boric acid/alcohol dip for annealing silver, using flux
over then entire surface I think would make a sticky mess of your
soldering surface PDQ and that I think would over a long period build
to be an unnecessary expense. Besides firing off the alcohol is
really pretty. (I’m not a pyro, I just amuse easily.)

But yeah occasionally I’ll anneal it naked. (Hey I do work from
home! grins)

Norah Kerr
www.besmithian.com


#9
Shouldn't you at least wear a leather apron? ; ) 

Nah Elaine, I gotta be FREE!!! HAHA… I woke up this morning
thinking, “I’ll bet that post is gonna come back on me…” First
off, everything posted today is true, at least in principle. Second,
here’s an interesting article by C.L. Brain about the subject:
http://www.silversmithing.com/1fire.htm. OK, here’s the thing. I
don’t work silver any more but occassionally. Back in the day, I
worked hundreds of pounds of it - was a time I checked out 3-5
pounds a week, doing piecework. Next, firescale is the bane of
silversmithing - we all know that. If you read the article above
carefully, you may notice that he dances around it, and never quite
just comes out and says, “You are going to have firescale, get used
to it.”, but nearly so. Back when I used silver a lot, I tried each
and every product that promised, “No Firescale”, “Firescale resist”,
Firescale killer or whatever. You know what? Not a single one of
them worked. I’d use it, I’d polish, and there it was, every time. If
anybody does have such a product I’d be real interested in hearing
about it, just for knowlege (if it doesn’t work I’ll flame it,
though). Flux most certainly does not work, as you’ll find every
time you solder silver. Less firescale? What does that mean,
exactly? Sure, it’s less firescale. You’re still going to have to
remove firescale, whether it’s more or less. The point being, since
you ARE going to have it when working silver, don’t be all nervous
about it. It’s just part of the experience. The worst thing you can
do is to heat silver to a cherry red heat (the heat before orange).
THAT will give you so much firescale it may destroy your piece.
Other than that, it’s just going to be there… Try to solder
everything before final filing, stuff like that. If you get it hot,
it will stain, unless you have an inert gas kiln or the like.

http://www.donivanandmaggiora.com


#10
Boric acid actually begins to from a sticky "liquid" at about
500-600 F 

THANKS Jim.

I flux all precious metals when annealing. Flux is cheap (when you
make it yourself) and firescale is something you can prevent. An
ounce of prevention is worth.well we all know.

thanks again Jim,
Susan


#11

There’s an informative article “The Lowdown on Annealing” in the
September issue of (Lapidary Journal) Jewelry Artist.


#12
I like the boric acid/alcohol dip for annealing silver, using flux
over then entire surface I think would make a sticky mess of your 

The question is, “Flux before annealing?” The real point, though, is
that for your basic silversmith annealing is the least of your
worries. If you anneal sterling at the proper temperature - 900F.
does it quite nicely, you will get little if any firescale. It’s the
soldering that gets you - 1200F, 1350F. And I personally have found
that boric acid is too hot for silver soldering - the melting point
is so high that it’s actually keeping the solder away from the
metal. That could just be that I’m a slave to my habits, but I’ve
just found that the boric acid dip gets in the way of silver
soldering, and any benefit is outweighed by it’s making soldering
more of a chore. Again, it can be done, but with fluoride flux it
just goes “zzziiiiip”. There are a few varying views on this topic,
and certainly putting flux will do no harm. I maintain, though, that
your biggest firescale stopper at the bench is the torch in your
hand, and how you use it.

http://www.donivanandmaggiora.com


#13
I flux all precious metals when annealing. Flux is cheap (when you
make it yourself) and firescale is something you can prevent. An
ounce of prevention is worth.well we all know 

I’ve been looking around and learning today - I gather Prip’s flux
is much liked for fire scale prevention - probably tomorrow (today)
there will be posts to that effect. I really couldn’t see using it
for some of my type of work - many tiny pieces that often are held
by hand for soldering, tight tolerances - it sounds pretty thick,
and even Handy Flux is waaaaay too cumbersome for me. But it seems
for big work it works well. And then there’s Argentum… I use
sterling for utility (models and such) at this point in life, so for
me it doesn’t mean much, but I have noticed a huge number of posts
about Argentum, like there’s a much steeper learning curve(?)

http://www.donivanandmaggiora.com


#14
I've been looking around and learning today - I gather Prip's flux
is much liked for fire scale prevention - probably tomorrow (today)
there will be posts to that effect. 

Prip’s is like water. I use a spray blower ( doesn’t clog like an
atomizer ) and I blow it only where I need it. I have come to learn
how to do it so I do not mess up my setup and loose or missplace
something. I posted the recipe somewhere on the forum.

It is:

120 g boric acid (roach powder get the cheapest an 99%boric acid)
80 g borax (from laundry isle boraxo)
80 g tri-sodium phosphate (from paint store)
1 gallon + 1 qt water

Mix all together until mostly dissolved ( all doesn’t ) Strain
through a stocking

I use this on everything I solder and all metals, all golds, bi-
metals and argentium. I use it when I anneal so I know my temps as my
studio is lit brightly by skylights.