Solder. An alloy used to join two metal surfaces, with a flux and the application of heat. Soft solder is an alloy of tin and zinc; it has a low melting point and is widely used because of this. Hard solder, also called silver solder, an alloy of silver, which fuses at higher temperatures. Both solders are used to affix loops to medallic items – the most common application of solder in the medallic field.However soft solder is also frequently used for bonding an appliqué or insert to a base medal, or to affix a backplate. Because of its ease of use, it's availability and lower cost, soft solder is also employed in the medallic field to back up or give strength to thin shells, galvanos, or as a drop-in between two electrotypes.
excerpted with permission from
For Artists, Makers, Collectors and Curators
COMPILED AND WRITTEN BY D. WAYNE JOHNSON
Roger W. Burdette, Editor