Is hexavalent chrome still hex chrome after it is plated on a part?

With all the new regulations regarding Hex Chrome I have been asked if the chrome that has been plated on our parts is hex chrome. we electroplate Steel Rods in Hexavalent chrome baths. I am not a chemist therefore, I don't have the proper answer but it is to my knowledge that the chrome left on the rod is elemental chrome. I am looking for a good scientific description of how the chrome is changed from Chrome6 to elemental chrome.

Lance Penfield
employee - N. Sioux City, South Dakota
July 9, 2010

Hi, Lance. Although the inner details of all of the complex intermediate reactions involved in chrome plating are the stuff of deep award-winning science papers, they can be skipped. Chromic acid (H2CrO4 or sometimes called CrO3) contains hexavalent chrome, Cr+6. The plating current adds 6 electrons per atom, and forms Cr+0 on the part. As long as the part is well rinsed (preferably in D.I. water), there is no hexavalent chrome in or on it.

Note: this explanation pertains to chrome plated parts. If you also have zinc plated parts or aluminum parts that are "chromate conversion coated", that would be a different story.

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Ted is available for instant help
or longer-term assistance.
July 9, 2010

Q, A, or Comment on THIS thread -or- Start a NEW Thread

No dead threads!
Your Q, A, or Comment puts this thread on The Finishing.com HOTLINE.

Disclaimer: It's not possible to fully diagnose a finishing problem or the hazards of an operation via these pages. All information presented is for general reference and does not represent a professional opinion nor the policy of an author's employer. The internet is largely anonymous & unvetted; some names may be fictitious and some recommendations might be harmful.

If you are seeking a product or service related to metal finishing, please check these Directories: