Hi everyone, I have some very basic questions that I cannot find
answers to in any of my metalsmithing tomes. I recently purchased
the basic soldering techniques video from Rio and it raised a few
questions for me. In the video he uses a borax/alcohol flux coating
over the entire (sterling) piece to prevent firescale, and then a
paste flux at the actual join. What is not clear to me is whether it
is necessary to use a preventitive for every soldering job (such as
jump rings and other small projects). If not, what is a good rule of
thumb for using it? My next question is in the same vein about
annealing. Is it necessary to use something to prevent firescale
when annealing or are annealing temps low enough that I don’t have to
worry about it? When soldering ss and karat gold jump rings, would
the borax/alcohol flux be sufficient or should I use a paste flux
instead?
I appreciate any light anyone can shed on this complex subject!
Hello Carrie, The key with the boric acid is to avoid firescale hence
the polishing process is reduced not eliminated. When you solder
anything, the piece needs to be heated to where it will take the
solder. In the case of silver, it is such a good heat conductor that
the whole piece will heat up even if you are soldering only the jump
ring. As you get better with a torch you will feel how quickly the
heat travels and judge from there which pieces you need to coat first
and which will be okay without it. A piece with hard to reach
polishing spots I will usually coat.
When annealing finished pieces it will help preserve the detail work
leaving you with less aggressive polishing job being needed.
As for the flux being redundant, I will usually always use flux even
after firecoating. It is thicker and a more reliable coating for
better flows. There of course are exceptions…I just soldered
hundreds of silver jump rings on a “super chain” (Byzantine) for a
necklace I taught my daughter to make. If I had fluxed each link the
coatings would have been a pain in the neck when manipulating the
chain from link to link to find the other unsoldered links. The fire
coat worked very well as a light flux for soldering the individual
links.
Carrie. I do the firecoat thing every time a flame is going to hit
the metal. Firecoat, burn off, and then flux the areas to be
soldered. I firecoat before annealing, every time. I have also found
that firecoating the brass leaves that I solder on to copper wires
for my fountains keeps the brass looking much better. ( I am using
Phos-Copper brazing rod in this instance ). The cumulative effect is
a much cleaner job and less cleanup. I also drill this into my
students from the first time they touch a torch. They eventually
learn to keep the solution bowl covered and not set it a flame too.
By the end if the class they too can see the results. It is the
cumulative effect that really helps. The cleaner you keep your work
at each step, the easier the final cleanup. Less time spent
finishing is money in the pocket.
Carrie, I might invite some differences of opinion here.
Theoretically, Prip’s should be put on any item for soldering but,
when soldering jump rings and similar small objects, such as the tips
of small pear shaped bails, I do not believe Prip’s flux is
necessary.
Now, having said that, if you are soldering the jump ring or other
small objects onto a larger item such as a bezel mounting etc, then
it is essential that the larger item (the heat sink) be covered with
Prip’s, and while doing that you might just as well cover the small
object as well. My students challange me often on this issue but I
explain that the small object can be quickly soldered with just a
self-pickling flux and little or no oxidation will be evident…I
said–evident. It is just too small to see it though it may be
there. It depends a lot on one’s skill with the torch and ability to
get in and out quickly.
Any borax flux will do in such a situation…Batterns, Aquaflux,
borax paste, I don’t believe it matters as long as the join is
squeeky clean and the proper torch flame is used. Cheers from Don at
The Charles Belle Studio in SOFL where simple elegance IS fine
jewelry! @coralnut2
Hi Carrie, The use of boric acid/alcohol to coat the items prevents
oxygen from interacting and causing oxide formation on the surface or
below surface(firescale). Flux is then needed to allow the solder to
flow in a controlled way. Mind you that boric acid/alcohol is not
necessary and I rarely use it. Flux on the other hand is important
and essential. Think of the boric acid/alcohol as a shielding and the
flux as a guide for solder flow. IMHO a “rule of thumb” for using the
boric acid/ alcohol coating is this: to coat diamonds in order to
prevent them from combusting when doing repairs. The boric acid
coating can damage other stones(corundum) as mentioned recently in
another post. The problem for me is that the darn borax becomes a
glasslike substance thats more of a pain to remove than simple
surface oxides. If firescale becomes a problem then adopt the
coating strategy or switch to alloys that reduced possible oxidation.
I have luckily rarely had firescale issues when using a charcoal
block(reducing atmosphere) but I still keep this method in my bag of
tricks.