Product Short Description: During the test formation of blue coloration indicates that the surface of the stainless steel does not yet pickled sufficiently . And if blue coloration does not appear which indicate surface has been satisfactorily pickled. Product Description: A ferroxyl test is a test done only to "detect" contamination. Once contamination is detected, then a removal procedure is carried out. During the test formation of blue coloration indicates that the surface of the stainless steel does not yet pickled sufficiently . And if blue coloration does not appear which indicate surface has been satisfactorily pickled.