Lead-free solder, torches, fuel, tips and the brushes, cloth and heat shields that go with a soldered joint.
Solder on potable water has to be lead-free — 95/5 tin-antimony or a tin-silver alloy. Old 50/50 tin-lead is still sold for non-potable and HVAC work and is not legal on a domestic water line in the U.S., so keep the two spools apart on the truck.
Fuel choice is about mass, not skill. Propane will bring 1/2" and 3/4" copper up to temperature; on 1" and above, or on a fitting with water still weeping into it, MAPP-type fuel gets there before the heat conducts away down the pipe. A joint that takes too long to reach temperature oxidizes and will not draw solder.
Almost every failed joint is a preparation failure, not a heat failure. The tube has to be cleaned to bright metal with cloth or a fitting brush, fluxed immediately before oxide reforms, and assembled dry. Solder is drawn into the gap by capillary action — heat the fitting, not the solder, and let the joint pull it in.
The solder alloy also sets the joint's pressure rating — our copper pipe and tube dimensions explain why the filler metal governs, not the tube, and where the lead-free limits come from.
