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Hexavalent Chromium Content


A discussion started in 2005 and continuing through 2017 . . .

(2005)

Q. 1. Are items such as fasteners that have Hexavalent Chromium plating prohibited under the RoHS directive?

James Starling
- Guelph, Ontario, Canada


(2005)

A. Items that are 'chrome plated' (think of the brightwork on a Harley-Davidson) have their chromium in metallic form (valence state zero) whether the plating bath they were plated in contained hexavalent chromium or not. So they are not prohibited.

But items that are zinc plated or zinc-alloy plated (including many fasteners) invariably require a 'chromate conversion coating' to retard rust. This conversion coating is largely a gel that contains the original conversion coating solution; if the parts were conversion coated in a solution that contained hexavalent chromium they almost surely would fail to meet RoHS standards.

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey


(2005)

A. There seems to be a lot of confusion about the RoHS regulations. These regulations relate to the use of various chemicals in electricals and electronics. Unless the fasteners are being used in electrical or electronic goods these regulations do not affect you.

If your goods are used in the electrical or electronics industry then Ted's comments apply.

Brian Terry
Aerospace - Yeovil, Somerset, UK


(2005)

Thanks Brian. You are right that the RoHS standards may not apply to James' product line, but his question seemed to imply that they did and that he was questioning whether the standards prohibited chrome plating.

They don't, but they do apply to hexavalent chromate conversion coatings, which are no longer used in the automotive industry and in other broad swaths of applications, either. Because they are probably potentially carcinogenic, and because widely accepted alternatives now exist, it's not a bad idea to get away from hexavalent chromate conversion coatings except possibly in aerospace where the need for reliability should trump all.

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey


(2005)

Sorry Ted,

Wasn't able to read such a specific meaning from the question and was not trying to contradict you either.

But, even in the UK, there seems to be a lot of confusion about how to apply the RoHS regulations and that they apply only to the electrical and electronics industries.

By the way, even aerospace is under very heavy pressure to lose hex chrome from their aircraft. We are a little slow in moving in aerospace, because of the safety factors involved, but we will catch up...eventually.

Brian Terry
Aerospace - Yeovil, Somerset, UK


(2005)

A. It may seem a trifle pedantic but hexavalent passivated finishes are prohibited in Europe for automotive applications under the End of Life Vehicle Directive(EOLVD) and on electrical and electronic equipment under the Restriction of Hazardous Substances(ROHS).The RoHS directive takes it scope from the Waste Electrical and Electronic Equipment(WEEE) directive which aims to minimise the impact of this equipment on the environment during their lifetime and when they become waste.The EOLVD has broadly similar aims.

John Martin
- cardiff


(2005)

Thanks, Brian. It's a confusing issue to me as I don't know all of these standards in depth.

Thanks, John, I don't think you are being pedantic at all. I think you are noting that regardless of whether RoHS specifically applies to particular components, the principle applies to a lot of components (and it will probably eventually apply to all).

But I have found that many people from outside the surface finishing field assume that chromium plating from traditional hexavalent plating baths is prohibited by these standards, but it isn't.

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey


(2005)

Q. We've been trying to puzzle this RoHS business out ourselves. Reading the EU directive, at one point, it says that hexavalent Cr is limited to 0.1% of the weight of the material. Do they mean the weight of the part? the weight of the plating ON the part? Then, at another point in the document, it says that the intentional use of Cr6+ is prohibited. Huh?

The weight percent limitation sounds as if it would be easy to meet. But if they are flat banning hexavalent Cr conversion coatings... It's not clear what they're trying to do. I wonder if they themselves know.

dave wichern
Dave Wichern
Consultant - The Bronx, New York


(2005)

A. to David,
The EU's Rohs requirement, It is required less then 0.1% in homogeneous material.

Here is an explanation I quoted from a training material wrote by Dr.John Lau

(1) Homogeneous material means a material that cannot be mechanically disjointed into different materials.
(2) The term homogeneous is understood as of uniform composition throughout, some examples of homogeneous materials would be individual types of plastics, ceramics, glass, metals, alloys, paper, board, resins, and coatings.
(3) The term mechanically disjointed means that the materials can be, in principle, separated by mechanical actions such as unscrewing, cutting, crushing, grinding, and abrasive processes.
(4) Using these interpretations, a plastic cover (for example) would be a homogeneous material¯ if it consisted exclusively of one type of plastic that was not coated with or had attached to it (or inside it) any other kinds of materials. In this case, the MCV of the RoHS Directive would apply to the plastic.
(5) On the other hand, an electric cable that consisted of metal wires surrounded by nonmetallic insulation materials would be an example of something that is not homogeneous material¯ because mechanical processes could separate the different materials. In this case the MCV of the RoHS Directive would apply to each of the separated materials individually.
(6) A semi-conductor package (as a final example) would contain many homogeneous materials, which include the plastic molding material, the tin-electroplating coatings on the lead frame, the lead frame alloy and the gold-bonding wires.

Anderson Zhu
- Shenzhen, China


thumbs up signThanks Anderson. But actually, to RoHS, a "homogeneous material" is whatever they want it to be :-)

Peter Newell - Through the looking glass and what Alice found there 1902 - page 110

'When I use a word,' Humpty Dumpty said, in rather a scornful tone, 'it means just what I choose it to mean -- neither more nor less.'

'The question is,' said Alice, 'whether you can make words mean so many different things.'

'The question is,' said Humpty Dumpty, 'which is to be master -- that's all.'


When speaking of a steel part with zinc plating followed by a chromate conversion coating, they want the steel part to be considered one homogeneous material and the plating plus the conversion coating to be considered another homogeneous material. This despite the fact that a child can remove most of the chromate from the zinc plating with a pencil eraser, whereas a skilled machinist can't remove the plating from the steel part with any machine in his shop :-)

It's probably best to accept that platers are Alice and the European Commission is Humpty Dumpty, and just let it be :-)

Regards,

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey


(2005)

Q. We are presently preparing to meet the RoHS directives. We are presently preparing to solicit the required information from our suppliers. I would also like to include the prohibited materials from the Aerospace. I know that Zinc and Zinc Alloy, Tin and Tin Alloy along with uncoated Brass are a concern. Where can I find more information on this topic along with the guide or standards.

Thanks,

Karen Scott
fiber optics - Ottawa, Ontario, Canada


(2005)

Q. I've got a doubt on RoHs Requirements

Here are my Queries

1. Stainless steel has (SUS 304) chromium as one of its composition materials. Hence Whether Stainless steel Complies RoHs requirements?

2.Is all chromium plating materials complying RoHs Requirements

Thirunavukkarasu Sureshkumar
- Singapore


(2005)

A. Karen: Maybe there is a typo in your inquiry and you meant that the materials you listed are not a concern? My understanding is that the RoHS materials are lead, mercury, cadmium, hexavalent chromium, PBB and PBDE.

Thirunavukkarasu: Stainless steel and chromium plating contain metallic chromium, not hexavalent chromium.

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey


(2005)

Q. I've read the above and am probably more confused than ever. I'm looking at designing an electrical appliance with a decorative, chrome plated, plastic cover. Can this be achieved and comply with the RoHS directive?

John Gills
Electrical Appliances - Christchurch, New Zealand


(2005)

A. Yes, it's compliant to my understanding because chrome plating is metallic chromium, not the hexavalent chromium that is restricted.

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey


(2005)

Q. I work for a Design/Development company working with customers to develop new consumer electronic products for various retail and commercial industries. Having reviewed the emails on this topic above, (and trying hard not to sound like a broken record) my interpretation is that injection molded plastic parts used on electronic enclosures (LCD monitors housings or computer keyboard housings for example) with a decorative polished chrome plated finish are exempt from the RoHS directive and can be used beyond 2006.

I have documentation from plastics suppliers and paint suppliers regarding compliance to RoHs and am also in the process of working with my fastener supplier on this too.

What I don't have is something similar for the chrome plating that we use on these plastic parts. Does anybody have something -- in writing -- that I can reference for this? So far, the only thing in writing that I've seen is what Ted has stated on this website. Should this be something that my chrome plating supplier should supply to me?

I'm sure there are many others that would find this documentation useful.

Alex Chong
- Toronto, Ontario, Canada


(2005)

A. You are certainly right that you need proof rather than people's opinions, Alex. Further, if chrome plated parts are not rinsed properly, it's probably very possible for them to be shipped while containing enough dried-on hex chrome to violate RoHS standards. I know of a manufacturer of chrome plated chain saw chains who seemed to want to dry as much of the hex chrome onto the parts as practical, minimizing the amount rinsed off and requiring treatment :-)

So either you or the plater probably must do sufficient testing to be able to certify the plating as hex-chrome free / RoHS compliant. Good luck.

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey



September 9, 2016

Q. If something is mechanically plated yellow 2, does that contain hex chrome?

Riley Mcilhon
assembled products - urbandale Iowa USA


September 2016

A. Hi Riley. When someone uses the slang 'mechanically plated yellow' they probably mean mechanically plated with zinc, followed by chromate conversion coating of a yellow color. Sorry, I'm not familiar with the term "yellow 2".

Traditionally, yellow chromate was hexavalent, so parts that are several years old probably do contain hexavalent chrome. For the last 10 years of so, trivalent chromating has been increasingly common to the point where yellow parts produced today are probably most likely hex-free. But it's not guaranteed.

Regards,

pic of Ted Mooney
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey


October 21, 2016

A. Salutations,

An educated guess would be that "Yellow 2" would refer to ASTM B633 [link by ed. to spec at TechStreet] for Service Condition 2 (SC2) which is the harshness of the operation would related to the thickness of the coating. SC2 is for moderate exposure to corrosion and is 8 micrometer thick (e.g. we use it for a dry environment with rare exposure to the elements for parts that we desire to last 10 years as an example). Our legacy drawings do contain similar lexicon.

Following up with Ted's comment, the best way to determine the coating would / could include a letter of compliance from the plater that it meets RoHS or that it does not have a hex chrome plate.

There are test methods and labs that would be willing to test to confirm plating for chrome but may be above and beyond your desire for accuracy.

Cheers

Erick Leong
- Buffalo Grove, Illinois, USA


October 24, 2016

A. I would be reasonably sure that the reference is to ASTM B695 [link by ed. to spec at TechStreet] "Standard Specification for Coatings of Zinc Mechanically Deposited on Iron and Steel." Therein, Type II refers to 'colored chromate conversion treatment.' This standard has not been updated to reflect current trends to 'trivalent passivates.' So your deposit could be a yellow hex or it could be a yellow tri. Your plater should have the answer, but you can get assurance from the ISO 3613 [link by ed. to spec at TechStreet] (1,5-diphenylcarbazide) spot test, although it has been known to give false negatives.

tom_rochester
Tom Rochester
Plating Systems & Technologies, Inc.  

Jackson, Michigan, USA


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