Staco stainless steel gratings can be pickled and passivated.
Pickling removes a thin surface layer from the stainless steel gratings, using an acid solution, which is usually a hydrofluoric and nitric acid mixture. For the pickling to be effective the surface should be clean and free of greases and oils. Pickling will remove embedded iron, surface iron contamination, heat tint and weld scale. Pickling will produce a dull matt uniform grey finish.
Passivation is a separate process to pickling. It can be carried out as an independent process or as part of pickling involving nitric acid in the solution. In this case passivation occurs sequentially and not simultaneously. Nitric acid is the usual strong oxidising agent used for chemical passivation.