I do quite a bit of enameling, but mostly create pieces I set in
bezels so I don’t solder as often as I should. However, I’m creating
a series of brooches and am soldering the findings directly onto the
metal before enameling. Here’s my problem: I’m using IT solder and
having a heck of a time trying to get it to flow. The brooches are
copper and the findings are sterling silver. I’m using a mixture of
50/50 black flux and Handy flux for the surface. The piece is
throughly clean when I start. I let the flux air dry before soldering
which has produced better results. What’s happening is that the
solder is staying in pallion form and not flowing onto the surface.
If I keep the heat on the piece, it eventually gets too hot, begins
to oxidize and gets dirty. Pickeling and starting over aren’t making
this better!
I’m choosing IT solder so I can fire my piece more times without
worrying about the soldering breaking down. I’ve done this before
with success so I don’t know what I might be doing wrong this time.
Could my solder mix be too old? What do you seasoned enamelers use
for solder? I’m about to drop-kick this IT to the curb and go back
to Eutectic!
Firstly, is the piece hot enough? IT solder will melt at around 720c
and flow at around 810c, the melting point of sterling is around 890c
so there is not a great degree of headroom between the pallion
melting and the finding slumping into a little pool.
Secondly are the pallions clean, that is free of oxide. I do not
have a great degree of experience with copper and those that do may
have a better idea, however I have experienced similar difficulties
with fine silver where I have been a little idle with the cleanliness
of the solder pallions. The silver oxide seems to form a little
envelope which contains the melting solder and restricts or
completely inhibits the solder flow. It is easily corrected by
abrading the IT solder to a clean metal surface. I find it easier to
undertake this prior to snipping it into the pallions.
Personally, I find eutectic solder fairly brittle for attaching
findings. I’ve had some successes, but also a number of pieces where
the finding broke off when under modest stress. I’m reluctant to use
it these days because of this.
I’m not a huge fan of IT solder, either; it’s not as brittle, but is
not great with the flow and doe snot offer the reliability under
solder that I’d prefer.
At this point I’m designing pieces so I can either use hard solder
to attach findings in places that have no contact with enamel, or
creating pieces that will be set like a stone so I can choose the
solder for the enamels that work with them, and for the structures
that work with the metal.
Don has given you some good advice but I suggest that you use a
quality Hard silver solder for attaching your findings to the back of
your enamels.
I was told to use hard solder rather than enamelling IT solder by
one of the UK’s best enamellers and for me it has always worked but
you do need to take care in both the placing of the finding and
susequent firing of the enamel piece. I always work in sterling
silver but I have used copper in the past.
I start by outlining the area on the back of the piece that will be
soldered with a lead pencil or some form of stop-flow to restrict the
flow of the solder within that outline and preventing it flowing all
over the piece.
I then, using flux etc, heat the piece flowing the hard solder on
the back. When the solder has melted I place the finding in position
using a cross lock tweezer. If it does not go on straight continue to
heat the piece, and not the finding, pushing the finding into
position using a solder pick.
You will need to fire your enamels several times in order to build
up the enamel in thin coats and if you do not protect the finding
joint, the hard solder will develop black pits in its surface so a
good coat of Borax or similar high firing flux must be used at all
times to protect the surface and prevent this effect.
Other points to consider: I don’t like my findings being put under
any stress during the enamelling process so I either suspend the
enamel on a “V” shaped stilt or use a ceramic board with a cut out
for the finding allowing the finding to hang free of any pressure.
Making your own, bigger/stronger findings helps too but I know that’s
not always possible.
I would also recommend that you try to have a metal edge to the
enamel design as it helps to protect the edge of the enamel and in
the unlikely event that you do need to replace the finding after
enamelling you can do so by holding the enamel piece upside down by
its metal edge on a “V” shaped stilt and resoldering using easy or
extra easy solder. If your enamelling is good it won’t crack.
For soldering under the enamel design use Eutectic as it contains no
zinc.
Other points to consider: I don't like my findings being put under
any stress during the enamelling process so I either suspend the
enamel on a "V" shaped stilt or use a ceramic board with a cut out
for the finding allowing the finding to hang free of any pressure.
Making your own, bigger/stronger findings helps too but I know
that's not always possible.
What’s this “ceramic board” of which you speak? I’ve been using
mica, and would be delighted to find an alternative!
The brooches are copper and the findings are sterling silver. I'm
using a mixture of 50/50 black flux and Handy flux for the
surface. The piece is throughly clean when I start. I let the flux
air dry before soldering which has produced better results. What's
happening is that the solder is staying in pallion form and not
flowing onto the surface. If I keep the heat on the piece, it
eventually gets too hot, begins to oxidize and gets dirty.
Here’s what I’d do in a job where the metal parts were liable to
oxidise during the soldering: add more flux while heating. Keep the
flame on the work area: put the end of your soldering pick in the
flame to heat it up and then dip it into flux POWDER to pick up a
bunch of fresh flux, add the flux to the work piece. If it’s good
flux, like a type of easiflo, you’ll prevent the copper from
oxidising while you heat the area up.
The other problem you may be having is the typical small-onto-big
soldering problem situation. I’d pre-melt the solder onto the
finding part, cool and clean, and then heat up the main piece and add
the finding when the piece is up to temperature.
The condition of the flux is your temperature guide as well as the
colour of the metal. Flux has an operating temperature range, and
within that it becomes runny and clear. Before that it’s sticky and
a bit murky.
I worry about you using a mix of two fluxes. Black flux operates at
about 900 - 1000C, so it will not be getting into its operating temp
during your soldering job here. Use a flux more connected to the
temp range of the solder.
By the way, eutectic alloy of Ag-28%Cu has a very precise
solidus/liquidus (both temps the same!). 779 degC (1436 F). For all
other Ag-Cu alloys there is a separation of solidus and liquidus
temps. If your solder is not flowing there is one possibility: it is
not yet getting to 779C at the right place.
You asked about the ceramic board that I use for firing my enamels.
Its called ceramic fibreboards which I purchase here in the UK from http://www.vitrumsignum.com look under firing tools. Its a white soft
board that initially turns black when you first fire it and then
returns to its white state for all subsequent firings. It heats and
cools very quickly and is widely used to insulate kilns etc and if
we can get this in the UK I am certain that you should be able to
purchase this locally.
One point you should be aware of is that champleve / cloisonne
enamels are made from 1-1.5 mm domed silver and they are never
counter-enameled and so no enamel on the back of the piece to stick
to the fibreboard. Its very good for providing a wide support for
pieces that might otherwise fold on the “V” trivet in the kiln.
Also very useful for holding small items for soldering as they can be
pressed into the surface without any heat-sink effect.
One point you should be aware of is that champleve / cloisonne
enamels are made from 1-1.5 mm domed silver and they are never
counter-enameled and so no enamel on the back of the piece to
stick to the fibreboard. Its very good for providing a wide support
for pieces that might otherwise fold on the "V" trivet in the kiln.
I disagree with you on your statement regarding cloisonne enamels.
You might make your cloisonne on 1-1.5 mm domed silver, but I use
26ga and it definitely needs counter enamelling. I also counter
enamel my 1mm domed silver. It is better to be safe than sorry.
Why would pieces fold on the “V” trivit in the kiln? I do not have
that problem.
There are differences between the Eutectic solder and the IT solder.
First of all, if you are going to enamel OVER the solder join, then
you must think Eutectic solder. The Eutectic solder is formulated so
that there is no zinc; it is made from only silver and copper. By
combining these two metals, you create a lower melting point for
either of the two metals alone. The 'formula" utilized is usually a
combination of 71.9% silver and 28.1% copper and produces the lowest
melting point when these two metals are combined. The interesting
thing about a Eutectic solder is that there is no so called “mushy”
state, but goes instead from a solid to a liquid once it reaches the
proper temperature for the flow point.
If you do have a solder, with zinc, as in the IT or in hard solder,
when you enamel over the solder, you are most likely to have bubbles
form in your enamel. You can, of course, use the IT solder where the
enamel is not going to be covering that spot.
From your description of your problem, I am thinking that you are
not bringing the entire piece to the proper temperature for the IT to
flow. Keep the flame moving all the time as you are heating. I would
suggest the use of the Handy Flux only, and not use any black flux.
You do need a flux that will stand up to the temperature you need to
flow the solder. The IT is designed to flow at 1490 F. When you talk
about the pallions not melting, your solder may be very dirty. Clean
with a bit of sandpaper on both sides before cutting and make sure
the flux is in contact with the solder as well as the base. Happy
soldering.
A big “thank you” to everyone who responded to my soldering query. I
thought my pieces were really clean, but have since re-cleaned
everything and had better luck. Isn’t dirty solder and pieces always
the case?! I also worked my flame a bit more carefully to keep the
larger piece hotter and keep heat off the smaller, sterling
findings. I discovered they were heating up enough from the copper
without additional flame.
As for those who expressed concern with my flux mix…it was how I
was taught when soldering with Eutectic or IT to copper. If I
remember correctly, it was to handle the high heat put on the piece.
I have tried soldering with just the Handy flux and it always burns
off before the piece gets up to temp. I never have a problem with IT
solder when I’m using it on fine silver, just the sterling/copper
pieces.
I’ll keep plugging along, figuring out the problem. Thanks again to
everyone for their help and advice. It’s really nice to know smarter
people out there are willing to share their experiences!
[...] As for those who expressed concern with my flux mix...it was
how I was taught when soldering with Eutectic or IT to copper.
Comes a time when what you were taught could become a launching pad
for updating yourself.
Re flux-technology, I think it’s important to recognise that fluxes
have been designed to actively operate within a certain temp range
ON THEIR OWN. Black flux (600-980C) would likely be fine, but
personally I find it’s a bit too murky to see the work during the
heat-up phase. There are other fluxes that work well at those temps.
Maybe try another type of Handyflux, or Easyflo.
If I remember correctly, it was to handle the high heat put on the
piece. I have tried soldering with just the Handy flux and it
always burns off before the piece gets up to temp.
Flux exhaustion. Is heating up taking a long time?
Here’s a quite good article about choosing the right flux for the
conditions: though it doesn’t mention my favourite form: powder.
Brian
B r i a n A d a m
e y e g l a s s e s j e w e l l e r y
www.adam.co.nz