Cadmium plating per Mil-Std-870

A. Brian -

Try this service for more information: www.doccenter.com
You can find out what any spec is by doing a search. You can also order specs if you'd like from this on-line service.

A. Thanks, Brian: cadmium can be applied from a cyanide or an acid cadmium bath, but the performance specification should be similar. Cadmium is nearly always chromated, from which you can get a blue/bright, a yellow, an olive drab, or a black color. It is also possible to dye the chromate (you may have seen 'metric blue' or 'grounding screw green' dyes); however, the dyed colors will be unsaturated and pastel-like, so don't go asking for fire-engine red or canary yellow

A. Hi Jim. Personally I've never seen an American shop attempt to formulate their own chromates (there is a lot to doing it optimally); I am personally only familiar with buying the chromate from suppliers.

A lacquer or water-soluble post-dip can improve the corrosion resistance (but is not always appropriate, of course). Don't consider it without the customer's knowledge and approval as it affects conductivity, paint adhesion, etc.

Update May 2013: These days trivalent chromates are almost universal and the chromate supplier supplies a matched post-dip. Good luck.

A. Hi Mohamed.

Chromate conversion coatings for cadmium plated bolts are available in any of those three colors. There are numerous (dozens) of standards for cadmium plated nuts and bolts. Most cadmium seems to be yellow chromated, and a lot is olive drab; but I don't know of specs that call for it to be a particular color except for specs that go with specific parts. Other readers may know though.

Thanks and Regards,