How to remove black coloured corrosion pitting marks on flapper valve steel?
February 12, 2008 We use very thin (less than 0.3 mm) flapper valve steel (20C material) parts for finishing. These parts are immeresed in oil to prevent corrosion. However, we have found heavy corrosion pitting (black coloured spots) on the parts after barrel finishing. Can you please suggest any chemical or methods by which these pitting marks can be removed?