Sustainability is metal-free leather tanning

20 August 2018



International luxury conglomerate Kering has sparked controversy with its desire to put sustainability first and endorse metal-free leather. Andrea Guolo assesses whether this is a clever marketing strategy or a genuine spark that will inspire the industry. He gathers expert opinion about the use of chrome and whether tanneries are really ready for change.


Kering wants metal-free leather, but can the company really obtain it? Reaching this goal not only depends on how much the company is willing to pay, but also on how satisfactory the results are with tanning methods that exclude using chrome and other metals.

The will of the French group, which controls brands such as Gucci, Saint Laurent, Bottega Veneta and Balenciaga – to name the most important ones in the industry – is not a secret. In the document ‘2025 Sustainability Strategy’, Kering sets out its aims within the field of raw materials, including the desire to “improve manufacturing processes to drastically decrease environmental impacts and health implications, such as implementing its chrome-free and metal-free leather tanning process across the group.

This position has been reiterated by Kering during meetings with suppliers, creating a sense of unease among tanneries that do not understand the reason for this decision, fearing it will prove to be problematic for the business more so than its bigger clients. If Kering can’t maintain the high standards achieved through chrome tanning using a new tanning system, it would risk losing Gucci, a key brand that is growing exponentially; in the first half of 2018, it grew 44%, which accounted for a large proportion of Kering’s total increased sales of 26.8%. By the end of the year, the holding controlled by the Pinault family could reach €12 billion, the equivalent of more than one and a half times of the total turnover for the European finished-leather industry.

With these figures in mind, it is necessary to ask whether the old ‘customer is king’ slogan is still valid. Even in the face of huge technical problems, Kering’s claim appears to be more like marketing for the term ‘metal-free’, rather than a real desire to be more environmentally proactive.

A problem for Italian tanneries

“From a technical and health point of view, for the final consumer and workers involved in the production process, the decision of switching to metal-free leather has no foundation,” says Maurizio Masi, a professor in applied physical chemistry, and head of Politecnico di Milano’s department of chemistry, materials and chemical engineering (Giulio Natta). “The proposed transition does not make sense because it aims to eliminate a tanning agent that does not create problems and is present in many everyday objects – think of stainless steel. This is also clear to health bodies that do not place limits on it, [unlike] other metals of other chemical compounds, where there are limits in the order of parts per million.”

Masi is a great supporter of chromium, particularly when it comes to seeing results during the tanning phase. “Trivalent-chrome tanning makes it possible to obtain a product that is qualitatively excellent from all points of view, from that of tactile sensation to mechanical properties, durability and allergometric compatibility,” he adds.

“Possible alternatives have more problems than advantages .“

Masi then highlights issues that arise when the trivalent chromium is removed to use aldehydes. “I am an environmentally conscious consumer and this is the reason why I’m horrified,” he states, going on to say that vegetable tanning does not produce consistent quality across all applications, as the tannins used are often not natural extracts. In the majority of cases, they are created by chemical synthesis “to obtain the constant quality necessary for industrial uses… so they enter fully into the petrochemicals supply chain. Unfortunately, the messages sent to the consumer are very simplified and we cannot transmit correct technical evaluations. If I say ‘metal-free’, the message takes hold.”

So why is chrome being attacked? “I think it’s a political manoeuvre from a party that wants to take a certain type of market away from Italy,” Masi answers. “The results offered by chrome tanning, which is an Italian excellence, are extraordinary for quality and durability.” Furthermore, “there is no risk for the consumer”, if the process has been carried out in Italy under the country’s strict standards. He adds that quality control may lack in other regions, so metals cannot be blamed for any problems.

This was also the opinion of an expert held in high esteem by the Italian Tanners’ Association (UNIC), who preferred not to comment on the merits of the discussions between Kering and tanneries.

Association opinions

In the UK, the considerations for potentially eliminating chrome tanning change – but not the complications.

It is to be noted that metal-free leather has advantages and inconveniences like any other tanning method.
– Gustavo Gonzalez-Quijano, Cotance

 

“The metal-free tannages are generally more expensive, energy-intensive and may not produce leathers with the necessary performance characteristics for all applications.

Thus, the tanners may be open to customer complaints because of this. They also create different issues for effluent treatment and waste disposal,” says Paul Pearson, International Council of Tanners secretary and director of UK Leather. “We do know that some customers have moved to request chromium-free leathers and tanners have been prepared to supply these, but equally, we also know that some customers have moved back to chromium-tanned leathers.”

In his view, transitioning to a metal-free process would be negative. “This would probably increase chemical production and consumption, energy use and effluent issues – and therefore costs – while not producing a range of leather that is suitable for all applications,” Pearson explains. So, is it an environmental or customeroriented request or just a marketing necessity?

“It is probably a combination of all three. There is a misperception that chromium-free is more environmentally friendly than metal tannages, and leather users want to be seen to be sustainable and environmentally conscious by their customers. The consumer, for the most part, doesn’t seem to be aware or care,” Pearson adds.

And what about tanneries? “Tanners will always seek to meet the needs of their customers if the technology exists to do so. However, our member association in the UK, UK Leather, undertook a survey that indicated that, at this time, there is no decline in interest or use of chromium -tanned leather,” he said.

The European Confederation of the Leather Industry (Cotance) observes the evolution of this topic, but without expressing an official position on the issue.

“It’s not new; it comes back cyclically on the Cotance agenda,” states secretary general Gustavo Gonzalez-Quijano. “However, I do not recall a debate addressing it from the angle of a request coming from the fashion sector. Our discussions deal with it from a technical, environmental or economical perspective. Since it is not an issue that calls for a collective decision, but rather for an exchange of views, one can say that the topic remains open in Cotance for further exchanges.”

So, what kind of problems could tanners encounter? “There are certain aspects to be considered, such as the availability of performance chemicals adapted to metal -free tanning, the specific water treatment issues that metal-free processes cause, and the higher processing costs and times,”

Gonzalez-Quijano explains. “It is to be noted that metal-free leather has advantages and inconveniences like any other tanning method. There is no ‘one-size-fits-all’ solution and there are good reasons for every tanning method having conquered the industry shares in their respective market destination. It is important, however, to understand that there is no tanning method that is superior to others, neither in environmental nor in technical or economic terms. It would be wrong and deceptive to play one method against another. In other terms, that would be a problem for tanners because it would divide instead of unite the industry.”

The discussion should be open and not limited to a customer/supplier point of view. “It is my understanding that the debate about tanning methods concerns the leather market and value chain,” Gonzalez-Quijano continues. “All stakeholders are concerned, including our chemicals suppliers and regulators. Everyone has to be ready to take up the issue in the respective sphere of competence.”

The chemicals market

Gonzalez-Quijano view is shared by TFL, one of the leading leather chemical businesses. “Traditional chrome-based tanning systems are still used for the majority of leathers made, but a main reason for moving away from this reliable and economic process is the risk of chrome-tanned leather forming Cr(VI). Metal-free tanning systems, as well as tanning processes based on certain alternative metals, will completely eliminate this risk,” a company spokesperson said.

But TFL admits that costs prevent chromefree technology from expanding into markets beyond automotive leather. “The total cost of chemicals is usually somewhat higher for chrome-free processes than for chrome tanning. However, these added costs are relatively minor if the total price of the article is considered, and not only the costs of chemical processing. Out of the available chrome-free tanning systems, we consider glutaraldehyde-based tanning systems to provide the best overall solution in terms of technical properties, reliability and economy.”

When it comes to the environment, there are pros and cons to consider. Waste containing chrome, for example, has to be treated separately and the metal has to be removed, while chrome-free processes simplify waste treatment operations and eliminate the need for separating floats, instead of allowing them to be collected and treated together. “On the other hand, the increased amount of retanning agents usually required in chrome-free processes results in an increased chemical oxygen demand (COD) load for the retanning float. This can be overcome and COD loads can be reduced by 50% using new technology that combines established glutaraldehyde pre-tanning technology with retanning, zirconium, which does not pose any hazards whatsoever to either health or ecology, and its exhaustion rates are exceedingly high. It should therefore be considered on a par with metal-free tannages,” TFL’s spokesperson states.

There are also disadvantages and benefits to consider regarding performance, which depends on the technology used. Chromefree leathers, for example, tend to have a lower resistance to heat ageing compared with chrome-tanned items. However, choosing state-of-the art retanning technology – based on high-fastness syntans – allows the former to perform as well as chrome leather. Despite this, TFL admits that chrome cannot replace high-performance waterproof leathers.

When asked if tanneries are ready for such a change, TFL says, “A significant number of tanneries have already made the change from chrome tanning to chrome-free technologies. Others run both types of tanning processes side by side. This shows that chrome-free tanning is a robust technology that can be implemented in existing tanneries, without requiring excessive investment. The key question, however, is whether industries processing leather and final consumers are prepared to pay slightly more for chromefree leather than chrome-tanned products.”

Do tanneries want change?

Because of their resistance and availability, a gradual transition to metal-free leathers is gaining traction, but existing technology prevents the industry from making bold shifts. In the meantime, tanners will have to share this issue with their customers, starting with Kering. But the French holding company is not alone wanting to eliminate chrome when the results achieved, in terms of sustainability, are justified.

The attitude of the tanneries is predictable. “We always follow the market,” says Bernardo Finco of the family-owned Italian tannery group Finco of Bassano del Grappa (Italy), and president of the Confindustria Vicenza’s tanning section. “From a technical point of view, this curious request from some brands may not sound sensible because the chromium salts are the best tanning agent, in terms of performance and stability.”

According to Finco, the panic surrounding chromium is excessive and without scientific merit. “In Italy, the request to move to metal-free is limited to a few brands and has an impact on the districts most associated with those brands, mainly in Tuscany. The tanneries will comply with the requests, with little conviction for the benefits of change and monitoring the consequences in terms of environmental management,” he explains.

Jean-Christophe Muller, Tanneries Haas’s CEO, who is also Cotance’s vice-president, does not produce metal-free articles but admits that, over the past two years, the pressure to do so has increased, saying, “We get clear requests from our customers, asking us to develop such leathers for all markets where the luxury industry is present.”

But he believes tanneries will struggle to synergise the two methods under one roof. “For me, it would be very difficult to produce at the same time, in one single tannery, chrome-tanned and metal-free or chromefree leathers,” Muller states, adding that he would have to guarantee to customers that his tannery’s process conforms with a client’s product specifications, all while ensuring that no contamination issues arise by having two kinds of leather production on one site. The tanner believes that it is easier to produce soft and milled leathers with chrome or metal-free production processes, but his tannery would find it difficult to produce calf, box calf or any other speciality leathers on this basis.

Muller concludes, “I have no doubt that it will be possible to realise a certain number of industrial productions on a no-chrome basis, but today, I am afraid that if the legislation is [obliged to suppress the use] of chrome, this would also lead to the disappearance of some of our specialities and involve the standardisation of our production.”

Gucci’s growth was a big contributor to Kering’s sales increase in 2018, so using metal-free leather could make the parent company lose one of its biggest brands.


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