On Wed, 25 Apr 2007 22:43:40 -0700, in rec.crafts.jewelry mbstevens
wrote:

On Thu, 26 Apr 2007 02:00:49 +0000, Abrasha wrote:

There you go again! This is NOT brazing!

http://tinyurl.com/cuqzf
...metallic bond is the main way brazing holds metals together.
Welding simply mixes the metals making them one chunk of metal.


Yes, though the difference between this and brazing is that the two
objects/surfaces/etc being bonded are both melted. Whether they actually mix
much depends on the type of welding. If both are the same type, and both
surfaces melt, they will solidify as one, recrystalize as one, without needing
to actually mix. If only one surface melts, as with your gold on silver
granulation (according to your analysis), then this is not brazing, because
you've not introduced a seperate filler alloy. Rather, the molten surface
diffuses into the non molten one, producing a bond. It's the same type of bond
produced by brazing, of course, but that's not really a valid label for it,
since no external bonding alloy is formed, if the gold does not melt. So then,
perhaps neither welding, nor brazing, is accurate. Rather, then fusing would be
most accurate.

However, I'd guess that when the silver melts, the gold surface in contact with
it at least slightly melts too, forming a thin layer of eutectic alloy. This is
then the same thing, metalurgically, as what happens with classic granulation by
means the the added copper. A eutectic alloy forms at the interface, giving the
bond. In normal single alloy granulation, the amount of that eutectic alloy
that can form is limited by the amount of copper and the temperature to which
it's raised. With gold on silver, though, because it's likely that the mix of
the gold alloy, with additional silver, makes a lower melting alloy, then the
potential supply of eutectic alloys is rather larger. how much forms will be
limited by the temperature, and by the melting point of the resulting mix. Now,
I don't know for sure that this will be what happens. It depends on whether the
addition of silver to the gold alloy would raise or lower the melting point of
the gold or silver. If either one is lowered, then what forms at the interface
is this new alloy, and then, the proper term, just as with classic granulation,
might be eutectic soldering, the term Littledale used, if I recall, to describe
his method of granulation using copper or other metallic salts to do the same
thing.

In jewelry use, brazing is a term seldom used. More commonly used in other
industries, where "soldering" refers to what jewelers call "soft solder", such
as lead soldering, the term brazing in industry generally applies to the same
sort of operation as we jewelers call soldering (hard soldering), and generally
implies the addition of a distinct brazing alloy, not the in situ formation of
one from parent metals.. In classic granulation, brazing/soldering might be an
appropriate term since additional external metal, ie copper from plating or from
reduced copper salts, is added to the joint resulting in a distinct third alloy
that forms the joint before dissipating into the parent metal. But in the
method described in this case, no external filler or solder or other metal is
added. The whole is simply heated until fusion takes place. Since it happens
with one or both surfaces at least slightly melted, "fusing" is likely the best
term. If it were done without heating to melting temps, (as in making mokume
billets), then it would be diffusion bonding. The term "fusing" is not
especially specific. It does not require both surfaces to be the same, or both
to actually melt. All it requires is that two surfaces or items melt together
to form a bond. One can melt, or both can melt, so long as they join in the
process.

But in the end, might I suggest that there's way too much argument going on
about the definition of the words. While words are important, much more
fundamental and important is to understand the process going on. After that,
the words are just tools to communicate, and in this case, even the words used
are not consistant between the jewelry industry and the rest of the world.

So can we just not get so worked up over which word? It's not the important
part of the content, nor worth getting angry about.

Peter