Q: What is in silver solder? Is it all basically the same thing?
A: The normal silver solders used by silversmiths and jewelers are a mix of silver, copper, and zinc, with sometimes the addition of a little cadmium for the extra easy types. The silver content ranges from as high as about 80 percent for very “hard” solders with high melting points, to as little as 30 percent for the industrial repair types that are generally intended for soldering metals other than silver.
The compositions for the most commonly used jewelry grade silver solders are as follows, in descending order of melting point, from Knuth’s “Jewelers’ Resource”. Their compositions may vary with the different manufacturers, especially in the zinc content:
IT (extremely hard) 80Ag, 16Cu, 4Zn (sometimes no zn)
Hard 75Ag, 22Cu, 3Zn
Medium 70Ag, 20Cu, 10 Zn
Easy 65 Ag, 20Cu, 15 Zn
Extra Easy 56 Ag, 22 Cu, 17 Zn, 5 Sn
Easy Flo 45 Ag, 15 Cu, 16 Zn, 24 Cd
In addition, there are “silver bearing” solders intended for low temperature work. These are primarily tin, with only traces (maybe 5 percent) of silver and other components. In essence, they are high performance substitues for lead solder (lead solder should never be used on silver items). They are often called silver tin solders, but in some cases are referred to as silver solders. They require a different flux than the regular jeweler’s solders.
by Peter W. Rowe M.F.A., G.G.