Can aluminum, stainless steel, or nodular iron be Parkerized?
No you cannot Parkerize aluminum or stainless steel. Regarding nodular iron, neither our supplier, Radocy, nor PJ’s Gun and Metal Care Products has any experience with Parkerizing nodular iron, however, there are many success stories re bluing it using the Radocy Rust Blue, although it may have a slight pinkish hue/reddish tinge.