Soldering is the process of joining two metal pipes together with a substance called solder.
It works by heating the two pieces when they are held together and then adding a solder material which will soften in the heat. The solder will melt and in the process flow into the gap between the two pipes, creating a sealed join.
Soldering can refer to both soft soldering and brazing. The differences between the two are the type of solder used to join the materials and the temperatures needed to melt them.
Soldering and brazing rods are pieces of metal alloys which have a lower melting point than the metals being joined together. Brazing rods, or hard solders, are made from alloys containing silver, copper or nickel which have a melting point above 450 degrees Celsius (842 degrees Fahrenheit).
Soldering wire, on the other hand, is made from a combination of zinc, copper, lead, bismuth, and antimony or palladium. These metals have a melting point between 180 and 190 degrees Celsius (356 and 374 degrees Fahrenheit).
For plumbing, a lead-free solder needs to be used. Lead-free actually refers to a solder which has a lead content of less than 0.2%, rather than no lead content at all. This is negligible enough to prevent lead getting into water supplies.
