A new high-temperature soldering system has been developed for use on copper, copper alloys, and low-carbon steel. The method is applicable to automobile radiators and home appliances. The system uses a unique sacrificial metal coating method to promote spontaneous wetting and spreading of zinc and zinc alloy solders on metallic substrates. The 10-5- to 10-6-cm thick, electroplated or sputtered, sacrificial nickel coating is absorbed by the molten filler alloy during soldering and produces a direct solder-substrate metallic bond. Preliminary measurements on butt joints with copper members give tensile strengths over 32,000 psi at room temperature using 95 zn-5al alloy as solder. Spontaneous wetting, spreading, and capillary penetration are extremely rapid and produce joints as easily as 50-50 tin-lead solders. Recrystallization or annealing of the wrought copper joint members is negligible at the soldering temperatures of 450 deg to 490 deg c and lower. A list of typical fluxes and solder alloys is included.