This process got to the exposed cast iron "righ now" without removing much nickel.
Al, are you saying that the solution started to eat the exposed iron (where the plating had worn away already) and without removing any of the remaining nickel? Was it starting to pit or wear away the exposed black iron?
I have been told it's very hard to remove nickel but easy to remove chrome. The two metals are not "similiar" but entirely diffferent beasts and do not react the same to chemical treatment I don't think.
But, if nickel is so hard to remove, how do they easily remove nickel from brass (lamps, etc.)? Perhaps the brass won't be eaten by the chemical but iron will or they use a different chemical process to strip nickel from brass than can be used safely on iron?
I like nickeled Griswold cookware with its polished surface & black iron insides. The remaining old, patinated nickel just shows the pan's age. Chrome pieces don't age so nicely plus their cooking surfaces are plated all over.
Steve