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Ted Mooney, P.E. RET
Pine Beach, NJ
The authoritative public forum
for Metal Finishing since 1989
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Test for cadmium plating and alternate for Cad plating
Current question and answers:
January 30, 2021Dear Mr. Mooney,
I am an Aero. Eng. in a small Aerospace Co. I do not have a mentor to ask questions of. Over the years, I have had various questions about materials. My google search for answers usually leads me to you. Thank you for your postings.
Now I have a question about Cadmium that affects me in my personal life. As I near retirement, I was planning to open an online costume jewelry store. Most decorative charms come from China. When I learned that they were loading their base metal with Cadmium, and passing it off as safe metals, it stopped me dead in my tracks. I only buy wire from the US that is labeled safe by California's proposition 65. But there are few charms manufactured in the US. Now I wonder about the stainless steel bowls that my dogs refuse to drink out of. I just bought a dishwasher with stainless steel on the inside. I bought an AIR Fryer with "coated" steel on the inside. How do I know if these contain illegal Cadmium? At my age I can't afford to have cadmium damaging my bones and organs.
Is there an inexpensive test for cadmium that I can use on all metal parts that are manufactured in China? At the moment I am particularly focused on stainless steel and steel with rust resistant plating. Some of the test kits I saw online won't work if iron is present.
Thank you for your help over the years.
Best Regards,
Margaret
- West Milford, New Jersey
A. Hi Margaret; thanks for the kind words.
Stainless steel contains no cadmium; although I'm not a metallurgist, it probably can't contain cadmium because of low melting point, tendency to sublime, etc. So no need to worry about that one.
Similarly cadmium is extremely unlikely to be on any cooking surface, not only because it's toxic but also because it's properties don't lend themselves to application on things like fryers. Even zinc plating is not used for such things and cadmium is more expensive, so I'd say it's not going to happen.
But yes, charms & jewelry can be made of cadmium and in fact some were imported to Walmart.
Although expensive test equipment like XRF and Beta Backscatter can identify cadmium, this is probably out of your price range. I am neither a chemist nor a practical plater so all I really know about differentiation without expensive equipment is what I read here, and thread 38853 offers some good ideas. Hopefully other readers who do such tests will offer you some more practical tips. Good luck.
Luck & Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
January 2021
⇩ Related postings, oldest first ⇩
Q. We are manufacturing certain transmission components for forklifter which are cadmium plated and yellow passivated. How do I check they are cadmium plated and not zinc plated by my supplier?
Can we replace cadmium plating by some other protective plating but same protective life?
(for example, electroless Ni plating)
steels - Chandigarh, India
2006
A. It depends on the particular component and its function, with no such thing as a universal replacement because no two things have identical properties. But my first guess would be tin-zinc alloy because it probably comes closest to matching most of the properties of cadmium.
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2006
Q. Whether cadmium plating is equivalent to yellow passivation or electro galvanizing?
V.Vijayalakshmi Veeramalaistructural design - Shuaiba, Kuwait
January 17, 2009
January , 2009
A. Hi, Vijayalakshmi. Sorry, I don't know quite how to answer your abstract sentence fragment in a way that will not be misleading :-)
But, to phrase it in slightly different words, there are instances where yellow passivation on top of zinc plating (electrogalvanizing) can be used in place of cadmium plating, and a number of instances where it can't:
- Cadmium is galvanically compatible with aluminum; zinc isn't
- Cadmium does not produce bulky, sticky, corrosion products; zinc does.
- Cadmium is more corrosion resistant in most real-world applications; however, this can be made up for by heavier zinc plating.
- Cadmium exhibits very good stick-slip torquing characteristics for fasteners; zinc doesn't.
- Cadmium is highly malleable for crimped and swaged connections; zinc isn't
- and there are additional differences.
Unfortunately, the issue of finding a replacement for cadmium always requires an evaluation of the specific application. While it is probably possible to avoid all use of cadmium, it is only possible by applying a wide range of substitutes depending on which properties of cadmium are needed for the situation, rather than by applying any single substitute. Rephrasing it, in hopes of making it clearer through repetition, NO material offers all of the qualities of cadmium; some substitutes offer some of the qualities, other substitutes offer other of its qualities, so the best substitute for a particular application depends on which qualities are most important for that application. Good luck.
Regards,
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
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