RoHS compliance of hexavalent chrome plating

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 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,

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,

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.

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.

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,

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.