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: This test kist is specially designed to test of PICKLED staineless steel or to test of presence of embedded iron in the steel surface . Use the “ferroxyl test.” Spray the surface with a solution of potassium ferricyanide. If free iron is present, a blue color will appear.