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"RoHS compliance of hexavalent chrome plating"



Current question:

Ed. note: Please!
No abstract questions.
Huh?

November 11, 2021 -- this entry appended to this thread by editor in lieu of spawning a duplicative thread

Q. Hello all,
question about Chrome plating --

Hexavalent-free in accordance with RoHS guidelines, does it mean the plating process can still contain hexavalent chrome but limited to 0.10% or the process is not supposed to contain any hexavalent chrome at all?

Please advise.

ram chowdary
- eden prairie, Minnesota
^


November 2021

A. Hi Ram. Properly rinsed chrome plating is zero-valent rather than hexavalent, so the question of RoHS requirements isn't really quite applicable. However, there are at least two important points to remember ...

• Chrome conversion coatings on aluminum and on zinc & cadmium plating are NOT chrome plating. Be careful to not use the term 'chrome plating' if you are talking about conversion coatings because, unless formulated to be hexavalent-free, they will leave hexavalent chrome on the parts, and probably in excess of RoHS requirements.
• Don't be misled by the term "RoHS" (Reduction of Hazardous Substances) into thinking that RoHS covers everything you need to know/do for compliance with European requirements regarding reduction of hazardous substances. There are other European requirements including EOLVD, WEEE, and REACH which may be applicable to different situations.

If, rather than posting an abstract question, you will please tell the readers your actual situation, you are far less likely to receive an answer which may accidentally mislead you.

Luck & Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
^



November 19, 2021

Q. Hi Ted,

I have an example following this thread that I would like to run by you.

We have a forged steel micrometer frame that is copper plated then put through two rinse tanks. It is then dried in an oven and sandblasted before chrome plating. At this point it is rinsed twice then placed in an alkaline cleaner with chrome reducer added. Again it would be dried in an oven.

Would it be wrong to assume that there is no remaining Hex Chrome on the parts at this point?

On a side note, I have enjoyed reading your answers on this forum over the past few years. Thanks!

Marguerite

Marguerite LaCroix
Shop Employee - Royalston Massachusetts
^


November 2021

A. Hi Marguerite. There would be no hexavalent chromium after the double rinse after chrome plating because the plating is metallic (valence 0) and any of the chromic acid should be well rinsed off (assuming they have reasonable flow). Most decorative platers would add a D.I. rinse, or make that second rinse a D.I. rinse, to make sure the chrome was totally free from any staining.

An anodic electrocleaner can turn chrome metal back to hexavalent chrome -- in fact chrome is sometimes stripped this way. I admit to not understanding why you are doing this. Is it to lightly strip/etch them to give the frames a frosted look? I would have expected the blasting to serve that purpose.

Using chrome reducer in that electroclean is evidence that you are in fact concerned about generating hex-chrome. I wouldn't know if you are using enough chrome reducer to keep the hexavalent at bay, but if there is even a faint trace of lemon yellow color or amber color or orange color, you're not.

I assume the parts are well rinsed after the electroclean? If so, you might be okay.

But if you are following some old practice to try to give a special look to the frames by etching them in an electrocleaner, and perhaps even baking some of that solution onto the parts, I would not be confident at all that you are RoHS-compliant. Interesting process :-)

Luck & Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
^




Closely related Q&A's, oldest first:

2006

Q. I'm currently searching the internet for postings about alternatives to chromium (VI) plating on steel towel radiators.

It needs of course to have a long life time and needs to be durable for daily use of drying wet (or at least moist) towels.

As far as my research have taken me, there seems to be no good alternatives for this use.

Does the plated product emit dangerous substances or is it only during the chroming process that this is an issue?

Further: Chromium (VI) has been restricted under the (EU) RoHS directive, as is probably well known. This covers only electrical products, so towel radiators are not restricted. But the chromium is still the same, isn't it: are the electrical products subject to other circumstances than products of chrome plated steel?

Thanks in advance.

Morten Hecquet
Business - Kolding, Denmark
^


2006

A. Hi Morten. Chrome plated materials can involve the use of hexavalent chrome chemicals during their production, just as stainless steel items may. But there is no hexavalent chrome in the finished product, only metallic chromium. Chrome plating is not restricted by RoHS. You can use trivalent chromium plating processes as an alternative, but the shipped product contains only metallic chrome either way -- no hexavalent or trivalent chrome. Good luck.

Ted Mooney, finishing.com
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
^

P.S. Nov. 2021: Note that Morten's posting is from 2006 and that he is in Europe. Although RoHS may not be an issue to concern him, REACH probably is.



October 21, 2010

Q. Hi, I am in doubt what to do to get a handle for an electronic product to be RoHS compliant.

In short I have a zinc cast handle which needs to be chrome finished and in Asia there still are an overweight of manufacturers working with hexavalent chrome for the electrolytic process.

I have found two vendors who both can do first copper plating then nickel plating before the final chrome plating but one of them uses trivalent and the other hexavalent chrome.

I had chosen the trivalent chrome until the environmental department in Denmark made me aware that it might not be needed after all when we are talking about a real chrome plating and not just a chromatized surface like you use for screws, heatsinks, etc. where the chrome content is still in a compound format where it can be released.

For an electrolytic process I have found the following from ECB (European Chemical Bureau):

"Electrolytic chromium/chromium oxide coated steel
Steels used in packaging, e.g. cans, are non-alloyed steel flat products and are used for drinks or food products. Depending on the application, the steel can be covered with a metal coating (tin or chromium) or with an additional organic coating. The two main steels used for packaging products are tinplate and electrolytic chromium coated steel (ECCS). Their technical specifications are described in EN10202. They are both certified for food contact materials. After tinning, tinplate is subject to a passivation treatment in which chromium and chromium oxides are deposited on to the surface, to improve resistance to oxidation and improve suitability for lacquering and printing. The most widely used passivation process for tinplate is a cathodic treatment in a solution of sodium dichromate (3.5 to 9 mg/m2). ECCS is always used lacquered. On the surface of the strip a coating mass between 50 and 140 mg/m2 (total chromium) is applied. Chromium (VI) is used in both processes, but is reduced to chromium metal and chromium (III) on the final product. Consumer exposure to chromium (VI) is therefore likely to be negligible from this source."

from the link:
http://ecb.jrc.ec.europa.eu/DOCUMENTS/Existing-Chemicals/RISK_ASSESSMENT/REPORT/chromatesreport326.pdf

according to this hexavalent chrome is turned into trivalent chrome and metallic chromium in the final product so there is no risk and it is RoHS compliant - my questions is now, is this valid for all electrolytic chrome plating processes?

Best regards
Jes Mosgaard
Denmark

Jes Mosgaard
product designer - Skive, Jutland, Denmark
^


October 25, 2010

A. Hi, Jes. I am not personally familiar with the treatments used for cans, so I appreciate the quotes that you provided.

Your question went several days without response, and I think that's because other responders, like myself, generally don't respond to abstract questions like "is this valid for all electrolytic chrome plating processes" because when the inquirer doesn't put things into a specific context, the responder is presented with the need to envision every possible scenario and develop a long list of "ifs, ands, and buts" in answer :-)

For example, shall we consider electrolytic chromate conversion coatings from hexavalent chromates a "plating" process? These are not free of hexavalent chrome in the coating.

As another example, although the chromium that is deposited in chrome plating is metallic (zero valence), I have seen hard chrome plated products like chain saw cutter links that were very poorly rinsed and which I suspect might fail RoHS inspection. As another example, I knew a plating shop that hard chrome plated hollow rolls and, due perhaps to a contract dispute with their customer over cost, they would not clean the dirty, greasy inside of the tubes, and would instead plug the ends. There is probably a chance that some chromic acid occasionally got through those plugs. Also I used to think it was safe to say that bright chrome plated parts were free of hexavalent chrome because you can't get them spot-free if there is still any chromic acid on them, but then I heard from a plater of shaped tubes who delivers spot free exteriors while believing that there may still be measurable hexavalent chromium in the crooks inside the tubes.

So, yes, chrome plating deposits are metal of valence state zero and are free of hexavalent chromium, but that is not an absolute guarantee that there is no risk and that the actual product is RoHS compliant. To get a more exacting answer you must describe your actual situation. Good luck!

Regards,

Ted Mooney, finishing.com
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
^


November 12, 2010

A. Jes Mosgaard, good day.
You live in Europe, your product, a handle, is made of zinc casting and it is for the electronic industry. This means your RoHS compliant requirement is to European Union directive, Directive/95/EC which is specifically for the electrical and electronic industry.
With that made clear, look up Amendment 2005/618/EC, Article 1, 'In the Annex to Directive 2002/95/EC, the following note is added : For the purposes of Article 5(1)(a), a maximum concentration value of 0.1% by weight in homogeneous materials for Lead, mercury, hexavalent chromium, polybrominated biphenyls(PBB),polybrominated diphenyl ethers (PBDE) and of 0.01% by weight in homogeneous materials for cadmium shall be tolerated'.
This means, as far as hex chrome is concerned, a maximum tolerated value of 0.1% or 1000 ppm is permitted in your handle. Assuming your handle is decorative chromium plated, although from a hexavalent bath, metallic chrome is deposited on your handle. They have a valence of 0. Properly rinsed part from a decorative hexavalent chromium bath, tested in approved labs by ICP-MS, shows a value of less than 5 ppm.
1. Both your Asian vendors, one using trivalent and the other using hexavalent decorative chrome process are RoHS compliant, although, I have reasons to believe the tri will be costlier. Proper rinsing, of course, for the hex bath.
2. The Environment Department in Denmark is spot on and, I might add, knowledgeable with current regulatory issues.
Good Luck.

SK Cheah
- Penang, Malaysia
^

For further discussion, especially including RoHS requirements for Chromate Conversion Coatings, please see --

Topic 35470 "RoHS restrictions on Hexavalent Chromium"



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