Leaded solders are suitable for a number of General Purpose applications. These products are safe to use with any of their Fluxes. Please note that General Purpose solder can't be used for Plumbing applications. 4 oz., 0.125" diameter solid wire solder on spool, general purpose solder. Alloy: 40% Tin, 60% Lead. Begins to melt at: 361 degrees F. Completely melts at: 460 degrees F.