Solders/Soldering

Solders and brazing alloys are fusible alloys used in the form of sheet, wire and pastes for joining and assembling components. Gold solders for jewellery are strictly brazing alloys rather than solders as they melt at temperatures above 450 degrees centigrade. They are made to melt at a lower temperature than the jewellery itself so that they can be applied to join two parts without damaging them. In gold solders, the melting range is lowered by alloying with zinc and cadmium, although the toxicity associated with cadmium fume is leading to its substitution by tin, indium and gallium, for example.

Solders are used in conjunction with hand-held brazing torches, or for mass-produced jewellery, in a brazing furnace, which is heated to just the right temperature for the solder to join together the various pieces without melting them. Complex jewellery assemblies will be put together by stage or step soldering, using solders that melt at different temperatures, so as not to disturb the joints already soldered.

Pastes (often known as brazing pastes) are simply alloys in the form of fine powder, mixed with flux and binders to form a mixture that can be dispensed in repeatable doses through fine needles. Pieces can then be heated by torch or furnace.