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Iridite 14 vs. 14-2

2003

I have an aluminum bracket that has been Iridited to class 1a per MIL-C-5541 [affil. link or DLA]. The question has now come up, what has been used, 14 or 14-2. What is the difference between Iridite 14 and Iridite 14-2? Thank you.

Leah McIntyre
- Cleveland, Ohio

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2003

14-2 contains "accelerator" Potassium Ferricyanide which helps the film to form faster. 14 does not contain an accelerator. Both meet all revisions of MIL-C-5541.

Practically all popular chromating compounds contain the same accelerator.Potassium Ferricyanide is a very tight complex and is considered by many technical authorities as harmless.

When the school boy engineers get worried about the accelerator, they use the plain formulations at higher temperature, higher concentration, lower pH, and longer time.

Robert H Probert
Robert H Probert Technical Services

Garner, North Carolina