Our shop uses a product called "Ospho" which is a Phosphoric acid solution which does exactly the same thing as the above products. Our local Napa carries it, and it comes in quarts. Like everyone else has said, prepping is the key, it will not turn flakes into solid metal again. Instead it just makes clumps of hard to remove flakes, so clean off all loose material first. Also, a good set of gloves and a mask or outdoor environment is a necessity, this stuff is tough and pretty good for removing nose hair! Good luck
