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Gun-Blue reactivity on cadmium plated, forged hardware

I am a parachute rigger and service parachute equipment. A customer has recently taken matters into his own hands and treated all the cadmium plated hardware on his parachute with Gun-Blue(Black Oxide?). I presume that the product was off the shelf from a sporting goods store. Much of the hardware also comes into contact with Nylon 6,6 used to make the webbing.Will Gun-Blue adversely affect cad plated hardware? What would it do to Nylon? In the industry we know of hydrogen embrittlement problems associated with people trying to chrome-plate cad-plated hardware. I am vaguely aware of some acidic compounds in Gun-Blue, but am not sure if I looked up the correct MSDS, or if there are different bluing products with different properties on the market. I certainly will submit this query to the original hardware mfg. and my peers in the parachuting industry.

Richard Fourie
Southern California Rigging Services - Perris, California, USA

This sounds like an absolutely terrible idea, and your customer is lucky to have you watching out for him. Hydrogen embrittlement is one possible problem, but the other is that he has probably stripped off the cadmium plating, and it may be vital to continuing smooth operation.
pic of Ted Mooney
Ted Mooney, P.E.
finishing.com
Brick, New Jersey

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