One of the suggestions was that I was not getting my piece hot
enough, and that I needed a bigger flame.) I adjusted my flame
to be 4"-5" inches long (trying to get a bigger, softer flame),
and this seems to be working better.... When I was using the
smaller flame, my piece would get glowing red, and the surface
would sometimes shimmer like liquid.......so, if my smaller flame
was getting the metal hot enough to melt (the surface, at least),
why was it not hot enough to flow the solder thru the join? The
solder did flow, but only around the join, not thru it (between
the 2 pieces).....
Your solder should flow just after the silver reaches a dull red.
Glowing red that produces a shimmering look is too hot. You've
actually "depletion gilded" the piece so that there is now a thin
layer of fine silver (no longer sterling) at the surface, and that
changes things (like soldering temperature). It also explains why
you're getting better results with the softer flame.
Are you bringing all of both pieces up to soldering temperature at
the same time? With skill and experience, you can "spot solder"
somewhat with sterling, but you really need to concentrate on
bringing the entire mass of both pieces up to temp simultaneously.
Make sure you dim the lights so you can see the silver reach the
dull red it needs to be. With too much lighting, it may look the
right color, but it is probably too hot.
I was wondering if it was because the smaller flame put the
hot blue cone nearer to the metal, so that the surface got
intensely hot, but the whole metal mass did not?...
Not to put too fine a point on it, but you are the one who puts the
flame nearer the metal, not the smaller flame, itself. Adjust your
oxy/fuel ratio for as large a flame as you need without a hissing
sound. This is known as a reducing (low oxygen) flame. Some call it
a large, brushy (or bushy) flame. Sometimes with large pieces of
silver, this isn't hot enough, and you'll have to pour on the oxygen
a bit more. Experiment with moving the flame closer to and further
from the metal, as some parts of the flame are hotter than others
(another element of torch control). Flame size matters less than
torch control, but you do need a flame large enough to bring the
entire piece up to temperature. Torch control is a technique that is
extremely difficult to describe. It can be demonstrated, but is best
learned through personal experimentation, and different techniques
are required for different soldering operations.
Also, a flame that is too hot, or applied for too long will burn off
the flux and render it useless. Once you've gotten the solder to
flow, longer exposure to the flame will raise the flow temperature
characteristics of the solder, and it will not flow until the
melting point of the silver. Get in, and get out quickly with your
flame. Use a solder pick (I use titanium) to spread the solder
across the join once it has flowed. You can't always rely on the
solder to go exactly where you want it. If the solder doesn't flow
shortly after the pieces reach a dull red color, chances are you'll
have to start over: Pickle, clean, mate the join flush, firecoat,
flux, place solder, heat.
I was also wondering if maybe the firecoat helped to keep
oxidation away from between the 2 pieces.......but why did'nt the
flux do that?.....(I am still trying to figure out why it appears
that there is flux residue between the 2 pieces...
The firecoat does help keep oxidation from the two pieces, as well
as cleaning them off. Also, the firecoat actually is a type of flux.
I don't remember if you mentioned in your original post that you
used your own self-made flux, but that could be why it didn't
protect from oxidation. My favorite commercial flux is Prip's, which
you may want to try. Battern's is also very good, and there are
others. If there is flux residue actually between the two pieces,
you haven't filed/sanded enough to mate them properly. While solder
actually can fill SMALL gaps (it really can, despite what you've
read) it's not easy to do, and weakens the piece. Pay close
attention to the fit of the join you're trying to make.
Thanks for letting us know how you're coming along. I, for one, like
to know if my suggestions have helped anyone. Keep it coming.
James in SoFl