Extract from the Pickling and Passivation section of the Australian Stainless Reference Manual (2012) published by Australian Stainless Steel Development Association (ASSDA)
The chemicals used in pickling and passivation are acidic and must be handled with due OHS and environmental precautions as well as neutralisation and suitable disposal of waste. In addition, hydrofluoric acid n(HF) is a schedule 7 poison. Stainless steel can corrode in service if there is contamination of the surface. Chemical treatments can be used to improve the corrosion performance of the steel, and hence its appearance in service.