I, too, have a water torch. I have the Swiss-made Spirflame, so I
can’t quite speak to the specific brand that you’re inquiring about;
however, I’m sure overall specs and operations are mostly the same.
That said, there is indeed a reason you were told by the pros at both
Rio and Otto Frei that you wouldn’t be able to heat any given piece
(especially silver or copper) thoroughly enough for soldering–or
even good annealing, for that matter.
The tips on most of the water torches I’ve seen, including mine, are
TINY. Like, hypodermic needle-size tiny. The diameters are regarded
in terms of gauge (like wire gauge). I don’t have my box in front of
me, but I think that my smallest tip is either a 26 or a 28 gauge,
which tells you how small they can get.
Water torches and their tips are precision instruments, and they’re
good for small, often pinpoint, soldering and repair jobs. They’re
excellent with metals like gold, platinum, etc. where you may not
want or need to heat the entire piece (platinum prong repair was
mentioned). Even with my biggest tip size (18gge), I would never
dream of trying to work on a bigger piece of any kind with it–and
I’d be hard-pressed to say I’d attempt even a smaller box ring,
because the flame distribution is simply not “bushy” and
all-encompassing enough. --There’s nothing you can do to make it work
for that, because it’s just not what they were designed for. I have
another torch that I use for standard, run-of-the-mill soldering,
So for everyday silver and copper soldering and annealing, I say
skip it–if you were going to do repairs or precision work with gold,
platinum, etc. bench-work regularly, then sure, it might be
worth the investment. [If you want to see what kind of jewelry can be
made with a water torch (in this case, a Spirflame), google “Giovanni
Corvaja.” I think there may even be a video or two somewhere out
there showing him using it. You should also be able to find a few
good perspective/scale shots of his work somewhere in your image
Peace, love and hair grease.