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Electrolytic Passivation

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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 dicromate but seems to work better in my anodize bath at 25% Nitric and 2% Sodium dicromate. 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

David Diosdado
Machine Shop - Hidaldo, Texas

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

James Watts
- Navarre, Florida

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