Easy reagent test to determine if austenitic stainless steel surfaces contain embedded iron contamination.
The Ferroxyl test is designed to determine whether austenitic stainless steel needs to be pickled or whether it has been pickled correctly. When structure on the surface of austenitic stainless steel has not been evenly restored, an excess of metallic iron will be present (so-called embedded iron) which will adversely affect the properties of the stainless steel. This can be left by carbon steel tools or welding (material).
See documentation for further information.