Decorative chromium electroplating from an electrolyte based on chromium trioxide has been successfully used for many years. The deposit satisfies many demands including aesthetics, durability and economy. However the materials used in this type of system have now been classified as carcinogenic. For this reason, new legislation is being introduced (or existing legislation is being tightened) to control, restrict or even prohibit their use. Consequently the chromium plating industry is being driven to change the way it operates and the materials it uses.
The goal is to manage this change for the benefit of all of the stakeholders by eliminating, rather than minimising the risk of exposure (of the industry workforce to chromium trioxide). This paper describes the primary applications for decorative chrome plate and the systems used to meet today’s demands, it then explains the principal macro drivers of change. Finally the use of best practice alternative systems, based on trivalent chromium electrolytes, and the potential effect on the supply chain are evaluated. The key question posed is, can the industry meet the challenge?
Decorative chromium electroplating has been successfully used for more than 80 years. The
majority of chromium platers use electrolytes based upon chromium trioxide and sulphuric acid, which have remained the default systems for many decades. The term ‘chromium plate’ is used to define more than just a single metallic deposit. Chromium electroplating refers to a multi-layer deposit consisting of a copper and/or nickel undercoat and thin chromium top coat. The function of the chromium layer is to provide a strong, powerful and effective anti tarnish to the bright nickel coating. Today chromium electroplating is carried out on many different and varied components including automotive bright exterior trim & alloy wheels, sanitary & bathroom fittings, tubular furniture, point of sale equipment (shopfittings) and consumer electronic goods.
However, chromium trioxide has now been reclassified as a hazardous substance that may cause cancer. Consequently, the industry now finds itself under intense pressure from international occupational health legislation and corporate demands to reduce the exposure effects of this material to their employees.
The industry faces two choices
- To minimise the risk of exposure and continue to use chromium trioxide electrolyte, or
- To eliminate the risk entirely by committing to the alternative trivalent chromium plating process
Adopting an alternative technology is a major step for the industry that will have both direct and indirect repercussions for the supply chain. For this change to be successful, the needs and opinions of all stakeholders must be taken into consideration. This paper makes the case that the elimination of risk secured by the use of trivalent chromium plating electrolytes is the way forward and that the successful management of this change within the supply chain can lead to benefits for all participants
Chromium plated plastic automotive grill
The Industry Today
Chromium plate continues to be the coating of choice for many applications. Demand for the
bright and lustrous finish continues to grow despite competition from other finishes such as organic coatings and vacuum deposition. Reasons why chromium has survived so long include not only unmatched aesthetics but also technical factors such as exceptional corrosion performance, multi substrate capability and supply chain factors such as economy bulk industrial scale, extensive installed applicator base and long application history and experience.
Chromium electroplate provides a high aesthetic performance and corrosion resistance coating for many industries, the largest market segment being the automotive industry. This industry can be broken down into various applications usually identified by the material being plated. Plastic (primarily ABS) is used extensively for bright trim (i.e. badges, grills); Alloy wheels, usually fabricated from aluminium (although the market now appears to be going in the direction of plastic cladding); Steel used for bumpers and trim, and zinc diecastings, used for articles such as door handles. Sanitary/Plumbing fittings is another large market segment, where the use of chromium electroplating still dominates due mainly to its easy cleaning and wear resistance properties. This industry also uses many substrates such as brass (i.e. plumber’s brassware), plastic and zinc based die castings, making electroplating a good choice. Chromium electroplating is also used for more traditional steel articles including tubular furniture, point of sale equipment (or shopfittings) and electrical consumer goods. These applications still use chromium electroplate extensively but as fashion changes, the threat of alternative finishes becomes more real. The use of chromium electroplate is very well embedded in today’s component design and usage, so that any changes in the process technology will have wide ranging effect.
Despite its inherent advantages, other factors, can affect the choice to use chromium. These include:
- availability of applicators (both number and quality),
- attitudes and buying preferences,
- fashion and culture.
In most applications demand for chromium electroplate is predominantly fashion driven and therefore cyclical. One of the best indicators of the current strength of the chromium electroplating market is to review the consumption of chromic acid and electrolytic nickel metal. Around 20 – 25% of the world’s chromic acid is used for metal finishing and demand grows at 2 – 3% annually. This growth rate is reflected in nickel metal consumption as well. Whilst the use of electrolytic nickel for the plating market remains consistent at around 8% (of total world nickel production), demand for total nickel metal increases globally at 2 -3%, Therefore, because materials usage, and in particular metals, is more efficient today than at any time in the past, we can safely assume electroplated nickel and chromium continues to show modest growth in both volume and applications.
Chromium plating technology and systems
What is generally referred to as bright chromium electroplate is in fact a thin coating (usually 0.1 to 0.3µm of chromium metal) over a bright and levelled coating of nickel. The actual type(s) of nickel used, the number of nickel layers and the total nickel thickness will depend on the base material being plated and the service condition specified (see Table 1). For example a component plated to service condition 5, will typically require a 20µm layer of semi bright nickel, a 10µm layer of bright nickel and finished by a 0.3µm of microporous chromium. Where a component is plated to service condition 1, it will have a minimum nickel thickness of 10µm (single layer, typically bright) and a coating of regular uniform chromium. When a less reflective ‘matt’ type finish is required, a satin nickel finish can be employed to replace the bright layer.
Table 1 – Service performance of chromium electroplate
Service condition number
Extended very severe
|Service conditions that include likely damage from denting, scratching, and abrasive wear in addition to exposure to corrosive environments where long-term protection of the substrate is required; for example, conditions encountered by some exterior components of automobiles.
|Conditions that include likely damage from denting, scratching, and abrasive wear in addition to exposure to corrosive environments; for example, conditions encountered by exterior components of automobiles and by boat fittings in salt water service.
|Exposure that is likely to include occasional or frequent wetting by rain or dew or possibly strong cleaners and saline solutions; for example, conditions encountered by porch and lawn furniture,bicycle and perambulator parts, hospital furniture and fixtures.
|Indoor exposure in places where condensation of moisture may occur; for example, in kitchens and bathrooms.
|Indoor exposure in normally warm, dry atmospheres with coating exposed to minimum abrasion.
All Organisations are subject to external drivers within both the macro environment and their own market place. These drivers can ultimately dictate the success or indeed the failure of whole industries or organisations within it. The metal finishing industry has had to face a change in the way it operates and in the choice of materials it can use in order to comply with environmental / health and safety legislation and pressures.
The chromium electroplating industry now finds itself at the centre of a health and safety debate that has the potential to drive major change within the industry. This debate revolves, either directly or indirectly, around the use of chromium trioxide. This is because this material is known to be both mutagenic and carcinogenic. When used in chromium electroplating, workers are exposed to its risks in three primary ways:
(i) When handling the dry material (i.e. dust exposure)
(ii) By electrolysis (i.e. as an airborne mist)
(iii) By skin contact with the process solution (splashes, drips etc)
These factors have precipitated new legislation and raised the issues into corporate policies. These risks only apply to chromium trioxide containing processes or materials. There is no such risk posed by the finished chromium plated surface which pose no such health risk.
Drivers for change
There are different specific drivers in North America, the European Union and Asia, although there is much overlap. Some of these are outlined here:
Control of Substances Hazardous to Health (COSHH) (EU) – This legislation requires users to carry out a risk assessment and then (i) find a viable alternative (ii) if one doesn’t exist to take preventative measures to avoid the user coming into contact with the substance. Best practice is option (i).
Control of Major Accident Hazards Regulations 1999 (COMAH) (EU) – This legislation is based on the potential for certain industrial activities involving dangerous substances having the potential for major accidents. A potential accident may cause serious injury to many people and/or extensive damage to the environment, perhaps some distance from the site of the accident. This legislation was prompted by previous major accidents involving chemicals (i.e. Flixborough UK 1974, Seveso Italy 1976, Bhopal India 1984, Basle Switzerland 1986). It requires that operators of COMAH sites take ‘all measures necessary’ to prevent major accidents and to limit their consequences to both people and the environment.
There are two levels (tiers) that classify a site as needing to register as a COMAH site; these are detailed in Table 2.
Table 2 – Overview of COMAH regulations
|Generic Categories of Dangerous Substances
|Quantity in tonnes ( > )
|1 VERY TOXIC
|9 DANGEROUS FOR THE ENVIRONMENT in comb. with risk phrases:
| (i) R50: “Very toxic to aquatic organisms” *(qualifying thresholds to be reduced July 2005 as result of amendments to COMAH Regulations)
| (ii) R51: “Toxic to aquatic organisms”; and R53: “May cause long-term adverse effects in aquatic environment”
Permissible Exposure Limit (North America) – The Occupational Safety and Health
Administration (OSHA) has amended the existing standard which limits occupational exposure to hexavalent chromium. OSHA has determined based upon the best evidence currently available, at the current permissible exposure limit (PEL) for hexavalent chromium, workers face a significant risk to material impairment of their health. The evidence in the record for this rulemaking indicates that workers exposed to hexavalent chromium are at an increased risk of developing lung cancer. The record also indicates that occupational exposure to hexavalent chromium may result in asthma and damage to the nasal epithelia and skin. The final rule establishes an 8-hour time-weighted average (TWA) exposure limit of 5 micrograms of hexavalent chromium per cubic meter of air. This is a considerable reduction from the previous PEL of 1 milligram per 10 cubic meters of air, or 100 reported as CrO3, which is equivalent to a limit of 52 micrograms as hexavalent chromium. As a reference, the UK has an exposure limit of 50 micrograms of hexavalent chromium per cubic meter of air (which is fairly typical of a European standard), 10 times more than the USA.
Registration, Evaluation and Authorization of Chemicals (REACH) (EU) –
To meet this proposed legislation, manufacturers and importers of substances are obliged to submit a registration to the newly established European Chemicals Agency. This agency will be responsible for the implementation of the REACH legislation, for each substance manufactured or imported in quantities of 1 tonne or above per year. Those using or making available a substance of very high concern will need to apply to the Agency for an authorization for each use of the substance within set deadlines. Applicants must demonstrate that the risks related to the use of the substance concerned are adequately controlled or that the socio-economic benefits of its use outweigh the risks, taking into account the availability of alternative substances (substitution) or processes. The socio-economic argument is deemed to be a less strong
argument and any authorization for use given on this basis will generally be time limited.
Control of Chromic Acid Mist (Perfluorooctanyl sulfonate, PFOS)
Perfluorooctanyl sulfonate (or PFOS for short) is a member of a large family of perflurooctanyl sulfonate chemicals. These chemicals have been used in a variety of industrial, commercial and consumer products. In chromium electroplating, these materials PFOS are used to lower the surface tension of the plating solutions to prevent the formation of harmful chromium mists above electroplating baths. These ‘mist suppressors’ have been in use for many decades, helping to eliminate hazardous chromic acid spray above electroplating baths. However, these suppressors present an environmental hazard themselves. The hazard associated with them is the persistence of PFOS in the environment, as well as its toxicity and bioaccumulation potential, indicating a cause for concern for the environment and for human health’. Based on this, the EU is now proposing restrictions on the marketing and use of perfluorooctane sulfonates (amendment of Council Directive 76/769/EEC). However studies into the use of PFOS in decorative chromium plating solutions conclude that at this time:
- These materials provide a unique means of controlling exposure to Hexavalent chromium mist and thereby controlling the OH&S risks associated with such exposure.
- No alternative to PFOS exists for mist suppression and it is unlikely that an alternative can be identified or developed within the foreseeable future.
- In order to reduce the amount of PFOS losses into the environment, it is quite possible that companies using these materials will have to prevent any solution loss to effluent through closed loop systems.
- The net effect of the above is that chromium platers now have to find alternative materials to control chromic acid mist. These alternatives are not as effective as the PFOS material, which makes it more difficult and / or expensive to meet the national health and safety requirements / legislation.
Corporate Social Responsibility (CSR)
An intangible factor which stretches across all geographical regions is the desire of major corporations to adopt safer and more environmentally acceptable technologies. Although these organizations may not actually use the processes, they can have a major influence in the supply channel by insisting that suppliers use less damaging materials by specifying alternatives. This may be one of the greater drivers for change as it essentially combines known health issues and current and proposed related legislations. Many larger corporations are now taking a proactive stance and asking their supply chains to seek alternatives to decorative chromium electroplating from hexavalent systems. This is particularly prevalent in Asian countries for in particular, automotive components and electronic consumer goods.
Today businesses have to take into consideration the needs and perceptions of diverse groups of stakeholders each of which has an impact on the way an organisation goes about its business. For an electroplating company these groups will probably include its customers, suppliers, employees, shareholders, competitors, industry bodies, OEM’s, government bodies, non governmental organisations and local residents. These different groups may have very different expectations and place sometimes what appear to be diametrically opposed requirements on the plating company. For example upstream customers will probably want the highest quality chromium electroplating at the lowest cost. Conversely conforming to ever more demanding legislation would appear to increase an organisation’s cost base and make it potentially less competitive to meet these customer demands.
This type of debate rages on in the business world, in many varied industries far removed from
the surface finishing world. Industry leaders such as Jack Welch have gone on record as saying that the time has passed when making a profit and paying taxes was all that a company had to worry about. Note also how companies such as BP have tackled the issue over emissions and the long term viability of fossil fuels. By addressing the needs of different stakeholder groups (i.e. shareholders and environmentalists), they have re-positioned the company as an energy supplier (not just fossil fuel based) concerned about long term sustainability and shareholder value. Contrast this to companies such as sportswear manufacturers and fast food outlets which have had to take a more reactive approach to their business after extensive criticism about 3rd world labour exploitation from indirectly related stakeholders such as Oxfam and governments. Whichever side of the argument you take, stakeholders are a critical factor to take into account when doing business, and their sometimes disparate views need to be taken into account.
What can be done?
As outlined above, the popularity and desire for chromium electroplate continues to be strong. Therefore, if the industry is to continue to satisfy its customers and stakeholders in supplying high quality chromium plate it needs to (i) meet the industry drivers (ii) consider alternatives:
(i) Meeting industry drivers – This is the option that most companies have adopted for many years now, even against the backdrop of increasing legislation and social awareness of the issues. This course of action has been followed due to the lack of suitable alternative coatings. However, as outlined above, the drivers now come from different perspectives (sometimes seemingly diametrically opposed i.e. mist reduction and PFOS removal), are more international (EU legislation), and sometimes quite intangible (i.e. CSR). A plater now faced with these multi faceted issues, may find it difficult to both understand and implement any necessary changes. This of course pre-supposes that further tightening of current legislation as well as new drivers do not surface, which in a constantly changing and more environmentally aware world is probably unlikely.
(ii) Alternatives – The most readily available technology to replace decorative hexavalent based chromium electroplating solutions are those based on trivalent chromium. This type of system either meets, or is exempt from the various legislation outlined above and is also perfectly acceptable in most corporate supply chains. However even though these systems have actually been in commercial use since the mid 1970’s they have not been viable for all applications. The main drawbacks being the colour difference and inferior corrosion resistance when compared to deposits plated from a traditional electrolyte based on hexavalent chromium. This has meant limited market penetration with trivalent based electrolytes accounting for less than 5% of the total global chromium installed process volume. The majority of companies using trivalent chromium tend to be captive shops (manufacturers and platers) which can both specify and plate to their own needs. New trivalent chromium technologies which answer these drawbacks are being introduced, allowing all platers to have a real alternative to replace hexavalent based systems in all applications.
Trivalent chromium plating
Trivalent chromium plated wire work
Trivalent based electrolytes are available which overcome the quality and cosmetic issues of older systems. The chromium deposits have purity very close to that produced from a hexavalent system, meaning that both the colour and corrosion resistance are virtually indistinguishable from each other. These new trivalent processes can also plate deposit thicknesses up to 0.3µm, making them suitable for meeting even the tough service conditions outlined in table 1. So do these systems mean a simple change with no adjustment to work practices? The answer of course is no. Subtle process differences and current industry acceptance mean that a certain amount of learning and adaptation needs to take place. Let us consider what adaptations are required by evaluating the existing needs of some of the key stakeholders identified above.
Chromium plated shower components
(i) The plater and its employees – The biggest change for a current chromium plater is to learn new work practices. This will require communication to the employee base on the need for change and the inherent benefits. Only by passing on this information will potential operators embrace the new work practices and implement systems as quickly and efficiently as possible.
(ii) Direct customers – Electroplaters need to be sure that their customers actively support moving from hexavalent based systems. This means raising awareness of the issues outlined above, so that customers can make their own evaluation of alternative finishes. Although the colour difference is almost imperceptible to the human eye, and some companies are today mixing both components from hexavalent and trivalent on finished articles, optimised supply chain management would use similar generic systems if sourcing from different plating lines.
(iii) Trade associations – Industry bodies have the opportunity to help manage change within industries as they are the voice of the industry and have lobbying access to the relevant government and NGO bodies. They should support its members the plating industry (i.e. the plating companies), by reviewing all the arguments, industry drivers and potential alternatives and presenting a balanced argument to all stakeholders.
(iv) Chemical suppliers – As owners of the technology chemical suppliers will be able to present the best alternative to chromium trioxide. They are also the key point of reference in the supply chain for consultation on best practices for change.
(v) OEM’s or specifiers – Some specifiers of chromium electroplate know that potential change in the supply chain are imminent and have started to discuss implications with their suppliers, platers and chemical suppliers. The two major market segments for specification driven chromium plate (i.e. automotive and sanitary ware) will need to instigate test programmes to validate and recommend alternatives. A programme of this kind takes many months and significant resources. Therefore a reasoned argument needs to be made for them to partner in any test programme.
(vi) Government departments and NGO’s – Government departments understand that non-consultative legislation would potentially mean job losses and risk votes. However they also know that industries do not regulate themselves very well, especially with regard to using less polluting / less harmful chemicals and their duty of care to employees. As described above, change to new technology takes time, both in education and implementation. This needs to be communicated in open dialogue so that change can be implemented in a controlled and timely fashion.
Overcoming legislation by introduction of improved safety practices by the continued the use of hexavalent based processes, may appear the most straightforward and cost effective solution. However failure to comply with new limits will probably mean having to revisit the issues repeatedly in the future as legislation becomes further tightened. If on the other hand, the industry decides that moving to trivalent chromium systems is the answer a longer term solution can be found. It is evident when considering the arguments suggested in this text that many stakeholders’ needs and perceptions will need addressing to facilitate change in the industry. No individual element of the supply chain can initiate complete change by itself. For this type of change to take place in a controlled and sustainable manner, the whole supply chain must work in a collaborative best practice way so that the benefits of chromium electroplate can be enjoyed for many more years.
- The goal for our industry is to manage the change away from the now increasingly unacceptable hexavalent based chromium processes towards the safer use of the newer alternative technologies in a way that benefits all stakeholders. Attaining this goal will be the challenge
- Overcoming legislation by introduction of improved safety practices and the continued use of hexavalent based processes may appear the most straightforward and cost effective solution to the current situation. Whilst this may be attractive to part of the supply chain in the short term, other more powerful influences may not see this as the best choice. This is not the goal since it will not satisfy all stakeholders.
I wish to thank Mr. Terry Clarke (MacDermid Inc) and Mr David James (SES Ltd) for their considerable input in the preparation of this text
 Robert Sherefkin‘Automotive News’ / January 2, 2006
 This includes all metal finishing including hard, decorative, chromates and anodising – ‘Chromium end use statistics / US Geological survey & The innovation group/Chemical profiles’, March 2006
 ‘Chemical market reporter’ March 2006
 Semi bright nickel is a low sulphur (<0.005%) nickel deposit which acts as a barrier to further penetration to the base material once the top layer has been penetrated.
 Microporous chromium is achieved by depositing the chromium over a special thin nickel layer which contains inert non-conducting particles, the special nickel layer being applied on top of either bright or satin nickel for micro-porous chromium, containing a minimum of 10 000 pores per cm2.
 ASTM B 604 – 91 (2003)e1 Appendix X1
 Also known as chromic acid (CrO3): Chromic anhydride, Chromic oxide and Chromium (VI) oxide (1:3).
 ‘Chromic acid’ COMAH Rev 2_1, January 2005
 ‘Overview of REACH legislation’ Dr Ernest Long, MacDermid Inc, December 2005
 ‘Environmental risk evaluation report’: (PFOS) 2004’, D Brooke, A Footitt, T A Nwaogu
 An ongoing research project PERFORCE (http://www.science.uva.nl/perforce/) which is financed by the Research Framework Programme is generating new data, e.g. on exposures, sources and routes and physico-chemical parameters of PFOS.
 CSR is the business contribution to sustainable development goals. Essentially it is about how business takes account of its economic, social and environmental impacts in the way it operates – maximising the benefits and minimising the downsides. See Marketing Concepts and Strategies, fourth European Edition 2001 – Dibb, Simkin, Pride and Ferrell