What is Soldering?
What a jeweler calls soldering would be called welding, if done using non-precious metals.
The basic procedure calls for taking two pieces of metal to be joined and placing them together. For jewelers, the solder usually consists of the same metal as the jewelry, only as an alloy with a lower melting temperature than the pieces it will bond.
When heated to the sufficient temperature, the metal’s molecules expand, leaving space between them. At this moment, the solder melts and flows into those spaces. When the metal cools, you have one solid piece.
What is Annealing?
Metal gets progressively harder when you work it. This has advantages, such as strengthening the prongs that hold a gem. However, when fabricating a new piece, this can make the metal difficult to work with. In extreme cases, you might even break the piece.
You can make work-hardened metal more malleable again by annealing. This is a simple process. Flux the metal to protect it from fire scale, then heat it with your torch. Heat white gold to a bright red and red gold to a medium red. Other gold alloys and silver should be heated to a dull red.…