Electrolytic Passivation

I'm an owner of a small machine shop, that provides service to Maquiladoras in the area, I do some Aluminium anodizing for my own fixtures but Right now I started to do some passivation for a new customer and I'm having trouble to passivate some small threaded parts made out of S.S. 416 and/or 430F, I have tried different electroless solutions with Nitric acid and Sodium dichromate but seems to work better in my anodize bath at 25% Nitric and 2% Sodium dichromate. Is it appropriate to use an S.S. bar at the Cathode? Is the mixture % right? Should I improve my cleaning baths and rinse? ''ll appreciate any comments

I have had my share of grief with 400 series passivation. One shop that I am well familiar switched to Stellar Solutions [a finishing.com supporting advertiser] citrus based passivation and never had any parts self destruct and had a better salt spray pass rate. It is safer also.