For the most part John Burgess is right. However, Sterling silver
contains 92.5% silver and 7.5% copper. Silver solders contain less
silver. As the percentage of silver is decreased, the melting
temperature is also decreased. The following list was copied from a
table printed in the Indian Jewelers Supply Company catalog. The first
two on the list will make a light yellow joint. It is best not to use
them on silver. The 70% has the best color match for sterling.
Easy-Flo #30 contains 30% silver, 27% copper, 23% zinc and 20%
cadmium it melts at 1125 ?F (605?C) and flows at 1145 ?F (710?C).
Easy-Flo #45 contains 45% silver, 15% copper, 16% zinc and 24%
cadmium it melts at 1125 ?F (605?C) and flows at 1310 ?F (620?C). Braze
560 contains 56% silver, 22% copper, 17% zinc and 5% tin it melts at
1145 ?F (620?C) and flows at 1205 ?F (650?C). Braze 650 contains 65%
silver, 20% copper, 15% zinc it melts at 1240 ?F (670?C) and flows at
1325 ?F (720?C). Braze 700 contains 70% silver, 20% copper, 10% zinc
it melts at 1275 ?F (690?C) and flows at 1360 ?F (740?C). Braze 750
contains 75% silver, 22% copper, 3% zinc it melts at 1365 ?F (740?C)
and flows at 1450 ?F (790?C).
There several other formulas for silver solder.
Sometimes terminology with solders can be confusing. When we refer to
hard solder versus soft solder we could be talking about the silver
solders versus the lead or tin bearing solders. Often we refer to the
75% silver solder as hard, the 70% silver as medium , the 65% silver
as easy , and the 56% silver as extra easy. I have not yet mentioned
the 80% silver 16% copper, 4% zinc solder known as “It”.
Have fun learning on this great forum.
Timothy A. Hansen
TAH Handcrafted Jewelry
web-site : www.home.earthlink.net/~tahhandcraft