[TheForge] Copper effecting Welding

[theforge@mailman.qth.net]

Food for thought re CU in a weld.  When weld wire is manufactured (both 
carbon and stainless), by hot rolling to roughly 1/4 inch diameter, then the 
wire is heated (annealed) and acid pickled to remove the scale and 
immediately plated with copper.  The copper acts as a rust preventative for 
both the steel and the stainless (many grades of stainless will also rust if 
not passivated at this stage), and acts as a lubricant in the cold drawing 
process where the wire is reduced in size by being pulled through a series of 
progressively smaller dies.  The copper is not removed and you will see it on 
most MIG wire (including Pure Iron weld wire) and on the non-fluxed stick 
rod.  I have never intentionally put CU in the forge, but have forged a fair 
amount of CU and don't recall ever having difficulty in forgewelding steel or 
iron after that, albeit most likely a different fire, but dont see it as a 
real threat.
Michael