BLACK BEING THE STEEL AND WHITE, THE IRON AFTER STAINING
I have seen this color scheme after rusting and etching stated both ways many times. In the majority of cases, it is said that the steel portion ends up black (or brown) and the iron portion ends up white... just as Drew has stated above. But here is a source that says "During etching, built up black ferro-ferric oxide is removed more rapidly from the steel portions of the barrel than the iron portions." See step # 7.
https://docs.google.com/document/d/18MIv...ref=2&pli=1Most often, it is said that the ferric chloride etching solution acts more aggressively upon the iron than the steel, but if the barrel is left in the etching solution too long, the black oxide will be removed from both. Also, I have most often heard or read that if the etch is too strong, it will attack the iron more aggressively and begin to cause the surface to become uneven as the iron is eroded. I'd like to actually rust, boil, and etch a piece of steel and a piece of iron just to see which one ends up black and which one ends up white. If I had to take an educated guess, I'd be inclined to go with the way Drew said it, just guessing that the steel would be slightly more resistant to corrosive agents than iron. But unlike Larry Brown, I have sometimes been wrong. Does anyone know for certain which is correct?
