i think for one thing, you should buy the solder from the supplier
you use for your mill products- for colour matching -particularly if
you use high karat golds in colours. I reccommend Hoover and Strong.
I have used them for over 35 years and most other
retailers/vendors/supply houses sell their brand.As for flowing
properly- almost any solder will work well with properly cleaned
metal to begin with, then an appropriate amount of flux ( preferably
a product like 4S labs brand " Cupronil " - it's a flux and
firescale preventative in one in an affordable, working
sprayer-headed bottle in a number of sizes! predating and consistent
unlike "firescoff" the new "ceramic" coating/flux now being marketed,
and in my opinion very inconsistent- not only in formula but the
sprayer heads work some of the time- I have tried it when it was
first introduced, and then reformulated and again...each time
different results and per bottle, inconsistent results from
application to application...needless to say, the company has made no
effort to provide a sample that reflects a consistent result, after
spending about 40 bucks in trials!..so it's not for me, whereas
Cupronil has remained the industry leader for years and years and is,
I believe labeled for sale by companies in addition to the
manufacturer's own label- it's a blue liquid flux,firecoat in one
sold in almost every vendor's catalogue).
So, keep the metal clean and grease free- even fingerprints on metal
can prevent solder from going where you intend it to.Solder isn't a
filler either- many people miss that fine point.It will join metals
precisely fitted and in order of operation from hard to soft
depending on how many subsequent solder joins must be made on a
design from the initial to adding on, say, accent stones in pre-cast
settings, or a pin and catch on a brooch, etc. Rarely is IT grade
solder necessary.
I hope this sums it up for you- clean metal in the same colour as
the solder with a good coating of firescale preventative ( build
layers if necessary in silver jewelry) and the most minimal amount of
flux applied with a clean applicator, to a relatively clean ( or well
seasoned ) soldering pad, or whatever you like to solder on.Even if
using a water torch, soldering is successful when you match colour
and hardness whether you choose to add flux to the water torch's
appropriate chamber or not- if you do use a water torch using
additional flux is not necessary unless soldering platinum in which
case it insure's a successful step in joining the metal....rer
