Summary for cadmium plating colors Discussion
Cadmium plating per MIL-Std-870 is discussed as a question of specification, not just color. Brian asked what the standard consists of and whether other cadmium plating colors or types could be used if the parts did not actually need to meet the military standard. Melissa J. Parks suggested looking up the spec through an online document service. Ted Mooney explained that cadmium can be deposited from either cyanide or acid baths, with similar performance, and that cadmium is nearly always chromated. He said the common chromate colors are blue/bright, yellow, olive drab, and black, and that dyed chromates can produce pastel shades such as metric blue or grounding-screw green, but not vivid colors. In a later question, Mohamed Arief Deen asked about bolt and nut colors; the reply said chromate conversion coatings on cadmium plated fasteners are available in black, white, or gold, and that many standards exist, with yellow and olive drab being common.
Q. I have some parts that have the following specification called out:
Cad plate per MIL-Std-870.
Does someone know basically what this standard consists of, Pertaining mostly to color and type of plating that is?
Also what other options do I have as far as color & type of Cadmium plating I can have done to these parts. As it is not a requirement that these part meet Mil-Std-870.
Thank you
Brian Case
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.
melissa.j.parks
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
🙂
Ted Mooney, P.E.
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1998
Q. Nothing to add to current topic but I have a question of my own…
The “olive drab” process is referenced by its ability to create a green color and excellent corrosion resistance…
Is there any information on activators? (e.g., part A–chromate Part B–?)
Please help me increase the corrosion capabilities beyond that of chromate alone. thanks.
Jim Wilkes
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.
Ted Mooney, P.E.
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January 17, 2013
Q. Cadmium plated bolt & nut in which color, i.e., black or white or gold? Is there any IS code for cadmium plated bolt, nut? If there is please mention it.
Mohamed Arief Deen
– Trichy, Tamilnadu, India
1996
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,
Ted Mooney, P.E.
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