What I did on my driver's hinges (and other phosphated parts), was to use "stainless steel' spray bomb as the primer, then a light misting of cast blast. Spray the cast blast far away from the hinge, you want a 'dry' looking coat, almost like it has imbedded dust. keep applying dry coats of cast blast until the sheen (2-4 should do it) of the stainless steel is minimized and the color of the cast blast darkens the hinge. My .02 I don't have a pic uploaded, nt sure if it would show accurately anyway