Q. We have a number of parts that require rework. Can you recommend a method for stripping nickel chrome from steel? We have attempted to use a sodium nitrate solution using six volts, but have not had good results. P.C.
A. You did not mention in your e-mail whether you are just attempting to strip the chrome or strip both the chrome and the underlying bright nickel. Chrome can be stripped in a number of ways, none of which are perfect.
A non-electrical method is to use a hydrochloric acid solution. The recommended concentration is usually 16 fl oz/gal at 110–130°F. another method involves using electrical current and either sodium hydroxide or sodium carbonate. Sodium hydroxide is used at a concentration of 7 oz/gal and sodium carbonate is used at approximately 9 oz/gal. The work is made anodic with 6 V at room temperature. This procedure works reasonably well but does cause smutting of the surface.
If you are trying to strip nickel from steel, sulfuric acid is recommended. A typical concentration is approximately 80 fl oz/gal at 6 V. Lead cathodes are usually used and the work is made anodic. This process must be used with care, since there is a tendency of the steel substrate to pit.