Olive green passivation as substitute to yellow passivation

A. I think it was for aesthetic and economic reasons, Suresh. Although gold or yellow chromate has traditionally been lower in corrosion resistance than olive drab, it was less expensive and some people would say more attractive (sometimes even used to mislead consumers into believing they are getting brass).

Color doesn't mean anything anymore though, since RoHS chromates must be hex-free, and the color of the old chromates was dependent on how much hex chrome was in them. Today the less dye and other adulterants we put in chromates to give them color, the better they tend to work.

A. Mr. Suresh, I would say for both: technical and commercial reason. Green passivation (in fact there is a family of green passivation: olive, olive-drab, military green, grey and so on) is more expansive than any common yellow one. The aspect is also important. After yellow passivation zinc deposit is still metallic, bright and attractive. Green passivation eliminates metallic bright and the aspect becomes less attractive for users. Except military users, who prefer non-reflective greenish coatings with high corrosion resistance to mirror bright ones. It's clear - why.

A. Richard, I'd suggest contacting the manufacturer of the hobby plating solution. Unless we have an actual chemical formula to look at our solutions are going to be guesses at best.