To use Neil's example above if you build a platinum piece with gold (gold family) solder you're going to have nothing but trouble, and that trouble will follow the piece everywhere. My comments on that topic were about platinum, not gold.
I am in complete agreement here. Gold solders, silver and in fact
some so called platinum solders should not be used for straight
platinum fabrication. Once you start talking about repair work all
bets are off and you do what you must and try to do the best you can
within the constraints of the clients desires, and budget along with
the practicality of and your willingness to rebuild the item.
When you talk about mixing gold and platinum you have an entirely different beast - and Neil is correct - I talked about gold soldering a diamond ring, because diamonds can't handle platinum heat. When I realized what is largely just crossed lines of commucation, last night, I looked down at my wedding band, which is a platinum center band with two 18 kt. trim pieces.
My comments were primarily aimed at mixed metal fabrication as that
is what I do day in day out, so crossed lines indeed. There are
solders / techniques to make mixed platinum and other metal joints
work and also some that are just about guaranteed to fail.
Regards
Jim
James Binnion
James Binnion Metal Arts