There has been some debate concerning the copper coating on 70S-2 GTAW Wire. The argument is that the copper coating should be removed before welding. I understand that you would not remove the copper coating in GMAW, but the debate still comes up. There has been discussion that the copper coating is from the drawn wire process and is a by product of cheaper drawn wire process and is not a desired result in producing welding wire. It has been said that better quality wire does not have copper coatings in its drawn wire production process.
Others state that copper coating should be sanded or removed before welding much like you would clean the base metal before welding. Both propents and opposers say that the copper coating helps the metal from rusting which may be true. I have even heard that the coatings may have certain properties and chemicals which improve weldability or other properties and shouldn't be removed.
I understand it may just be a matter of prefrence, but I am looking for both PROS and CONS for removing this coating, weither wire with out the coating exist and if it is superior, and if there are any applications where the coating must or must not be removed (i.e. critical components).