Over two decades later, that same substance is still used as a rust-inhibiting plating on industrial fasteners.
Scrutinised by the European Union, regulated by the state of California, and labeled a ‘carcinogen to workers’ by the US Occupational Safety and Health Administration, zinc yellow with hexavalent chromate has become a term industrial fastener buyers must be aware of, as environmental safety and sustainability become front and center policy in most every global organisation. The story of sustainability in the fastener industry is bigger than simply recycling steel parts. We must think about the entire lifecycle of a product and how that product’s end of life impacts the environment and the human race.
Zinc yellow fasteners with hexavalent chromate are common, as the plating has attractive anticorrosive properties that can be used for a wide variety of applications. While such fasteners are not outright banned for sale, industrial buyers are avoiding them. According to OSHA, workplace exposure to hexavalent chromate may cause lung cancer in workers who breathe airborne hexavalent chromate. In addition, it may cause irritation or damage to the nose, throat, and lungs if ingested at elevated levels. Direct skin contact with hexavalent chromate can cause non-allergic skin irritation. Contact with non-intact skin can also lead to chrome ulcers, which are lesions on the hands or in the nasal cavity. Much of the risk is borne by workers who are in and around the processing and plating of fasteners using hexavalent chromate.
This means that such fasteners, if restricted, may be less available, if available at all. Thus, zinc yellow fasteners may not be available if the demand for hexavalent chromate falls; buyers will need to be prepared to source alternatives. Despite renewed emphasis on recycling and the trend toward a circular supply chain, fasteners plated with zinc yellow hexavalent chromate still find their way to the landfill. The combination of worker exposure and environmental risks from discarded fasteners has caused regulators and industry leaders to take stiffer precautions of their use and distribution.
According to Kevin Connolly, applications engineer at Earnest Machine, the automotive industry has moved away from buying zinc yellow fasteners. Those customers are most concerned about the toxic effects of fastener platings and coatings if they degrade in a landfill. This is especially applicable to a vehicle’s “end of life” where such degradation may take place and be toxic.
“It is easy to look at fasteners made from steel and make the correlation to scrapping and recycling when we talk about sustainability,” states Patrick Ginnetti, director of marketing for Earnest Machine. “The story gets more complex when we start to examine the entire lifecycle of the product, who comes into contact with these products and how they are disposed of at the end of their life.”
The fastener industry is likely to curb the use of such platings on fasteners and work with buyers to find viable alternatives as regulators focus on hexavalent chromate. One regulation established by the European Union is REACH (which stands for Registration, Evaluation, Authorization, and Restriction of Chemicals). It is intended to protect human health and the environment from the hazards of hexavalent chromate, as well as other chemical substances. In addition to REACH is another global regulation, RoHS (Restriction of Hazardous Substances). RoHS is also known as Directive 2002/95/EC. It restricts specific hazardous materials found in electronics. This direction ensures that any products containing hazardous substances be properly disclosed to facilitate their proper disposal at the end of their useful life. As demand for zinc yellow fasteners diminishes, the supply chain economics for them will ultimately change and restrict supply. However, it will be a long road to rid the industry of hexavalent chromate.
The increase in regulations should act as a prompt for anyone accustomed to purchasing zinc yellow fasteners to consider an alternative procurement strategy. The good news is Earnest Machine can help specify and source alternative platings to ensure equivalent anticorrosive properties to meet your customers’ application specifications. It is essential that fastener manufacturers, distributors, and buyers are aware of alternatives, as there could be a mandatory transition to alternative platings.
Three key features need to be taken into consideration when deciding on the alternative: corrosion protection, cost, and plating or coating thickness. An alternative plating or coating must be able to replicate the properties that are possible with zinc yellow plating. Alternative platings to zinc yellow with hexavalent chromate include trivalent zinc yellow. This provides a similar yellow color but does not meet the same corrosion protection as a hexavalent yellow. To achieve the same corrosion protection as a hexavalent zinc yellow, a trivalent zinc yellow also needs a topcoat sealer, which makes it more expensive than hexavalent zinc yellow. Trivalent zinc clear is another alternative, and provides less corrosion protection compared to zinc yellow with a hexavalent chromate, but is food-safe and environmentally friendly.
In summary, zinc yellow fasteners are not banned or overtly prohibited. However, there are some regulations against hexavalent chromate, worldwide, that are driving large buyers of fasteners to avoid them. This will affect the industry and give ample reason for fastener buyers to have an alternate procurement strategy.