Water repellency: The choices, trade-offs and challenges behind a greener dry

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Now that winter weather has swept the Northern Hemisphere, a lot of people are bundling up in waterproof jackets and other outdoor gear before heading out into the elements. Nothing beats staying dry on a cold and wet day, right? But have you ever stopped to think of the chemistry behind your rain-proof yet moisture-wicking apparel? And how green is it?

As it turns out, waterproofing is in the midst of a largely behind the scenes migration toward greener chemistries. Although this is just small piece of the overall sustainability profile of apparel and footwear, it is an excellent example of the complexities of going green from research and development, through global supply chains, across multiple government regulators, and ultimately into the hands of the consumer.

Long-Chain Perfluorinated Chemicals

In the early 2000s, the U.S. Environmental Protection Agency became concerned about the accumulating research on long-chain perfluorinated chemicals, and particularly perfluorooctanoic acid (PFOA), a chemical found as an impurity in preparations used to make materials water and dirt repellent like stain resistant carpets. This C8 chemistry was also used to produce fluoropolymers which have been put to use in products that make consumers’ lives easier—from non-stick pans to waterproof boots. But numerous research studies found that PFOA persists in the environment, is bioaccumulative, can be found in blood samples of wildlife and people around the world, and has been shown to cause cancer and developmental problems in laboratory animals. It should be noted that the concern was not that the user of the product such as a raincoat would be exposed directly, but rather that between the chemicals manufacture, application, product washing and disposal, it made its way into the environment and eventually back into humans.

Based on these concerns the EPA began a voluntary phase-out program with the eight major chemical manufacturers of PFOA with a goal to eliminate the chemical in emissions and products in the U.S. by 2015. The EPA just released 2014 progress reports, which show that all of the companies are on track to meet the 2015 deadline, and many have already completely phased-out this chemistry. According to the EPA the manufacturing of long-chain perfluoroalkyl carboxylate chemicals (another way of identifying this chemical group) by companies not participating in the voluntary program will also cease by the end of 2015. This January, the EPA released a new ruling that any future new manufacturing, importation and processing of these chemicals would have to be approved through the EPA. Regulators in Europe have also expressed concern, with Norway issuing the strictest standards in the world for PFOA in consumer products, a limit of 1 microgram per square meter.

That being said, brands who make waterproof or water resistant products have been largely in a position over the last decade of voluntarily reworking their recipes (or more commonly, requiring their suppliers to rework recipes) to eliminate this chemistry. Doing so can be more complex than one may initially think. One camping tent, for example, may contain 80 different parts. So there is a lot of retooling needed to make changes across the board.

Short-Chain Perfluorinated Chemicals

But if long-chain perfluorinated chemcials (PFCs) have fallen out of favor, what then is being used to make our clothes waterproof? According to the EPA, there are over 150 alternatives. The closest group of alternatives are short-chain perfluorinated chemicals, a C6 chemistry. This group is generally considered to be safer as they are less persistent in the environment and less toxic, while manufacturers are finding that their waterproofing properties—with some extra preparation—are equivalent to long-chain PFCs. Bernhard Kiehl of the Fabrics Division Sustainability Team for W.L. Gore & Associates, the makers of Gore-Tex®, has been working with their suppliers to eliminate PFOA from all of their products over the last ten years. PFOA showed up as an impurity in the water repelling agent that the company purchases and applies to their products. By 2011 Gore had met this challenge for most of their consumer products and has more recently eliminated PFOA from all their products, including professional products—uniforms for fire fighters, the police, medical workers and others—which have higher performance requirements. “We believe we are one of the first companies to complete this project across the entire range of products,” says Kiehl.

Other outdoor brands are also busy eliminating PFOA by requiring their suppliers to provide PFOA-free material. Ensuring that this happens is a challenge in an industry with a long and broad supply chain. One way many brands have accomplished this is by working with Bluesign Technologies, a company based in Switzerland that provides a sustainable certification of products. Bluesign looks at a manufacturer’s recipes and processes, among other things, and works with companies until they meet Bluesign’s standards for environmentally friendly and safe production. By the end of 2014, Bluesign eliminated all C8 chemistry from their approved chemicals list, so all of the products certified by them must use either C6 or C4 technology, or one of over 30 non-PFC alternatives they offer.

The industrial advantage of long-chain PFCs is that they are a one-size-fits-all solution. Moving to C6 chemistry means that more care needs to be taken in the preparation of the fabric. Different types of fabric and different constructions have different processing requirements. The preparation of the fabric must be perfect and may need an additional washing and drying cycle. “That was a huge learning curve for many brands and many textile mills,” says Peter Waeber, CEO of Bluesign Technologies. “Today a C6 technology comes close to a C8 if all those conditions are perfect.”

“After looking into several options, [short-chain PFCs] was what we believed the most environmentally responsible choice,” says Bernhard Kiehl. “You have to look at the entire life cycle and what a replacement does. You have to look at wash frequency, the frequency of needing to apply an aftermarket water repellent, how the entire lifetime of the jacket is affected by loss of performance and so on.”

Another group looking at alternatives to long-chain perfluorinated chemicals is the Outdoor Industry Association’s Chemical Management Working Group who formed a task force with the European Outdoor Group, the German Sporting Goods Association, and the Zero Discharge of Hazardous Chemicals Group to work on, among other things, the water repellency issue. The group put together a research needs scoping document outlining data gaps, challenges and opportunities of different waterproofing materials, as well as outlining use cases and performance requirements to get a sense of what is really needed and what is overkill for a particular application. The outdoor industry is clearly interested in moving away from chemicals of concern that may eventually (or have already) land on the growing list of restricted substances regulated by REACH, the EPA and California, or otherwise attacked by activist groups like Greenpeace. “One of the biggest challenges of making progress across the board is the disconnect between academia and research organizations and the on-the-ground needs of the industry,” says Beth Jensen, Director of Corporate Responsibility at the Outdoor Industry Association. Jensen hopes that efforts like their scoping document will help facilitate a critical need for industry-informed academic research. Without the visibility into what choices alternatives present, product designers are not able to make the most sustainable decisions.

Short-chain PFCs, as the most known substance among the alternatives, is currently a favorite, but some express concern that C6 chemistries will ultimately be a “regrettable substitution” or at least an example of over engineering for consumer products. Nicholas Nairn-Birch of the EPA’s Chemical Control Division explains, “'Short-chain alternatives are reviewed by EPA's New Chemicals program against the range of issues that have caused past concerns with PFCs, as well as any issues that may be raised by new chemistries. Current research and testing results demonstrate lower toxicity and bioaccumulation concerns for short-chain alternatives relative to their long-chain counterparts. EPA's review of alternatives is still on-going.”

Others point out that while C6 is needed for professional fabrics and personal safety gear, it is not needed in simpler applications for consumers. “You can only repel oil or oily stains with fluorinated chemistry, but if you are just talking about water or rain, fluorine-free finishes are very much at the level of fluorine containing finishes” says Jan Beringer, Head of Research & Development, Department of Function and Care at the Hohenstein Institute in Germany. Peter Waeber concurs that there are currently non-PFC alternatives that can endure 25-40 washing cycles, and correctly points out, “How many times do you wash a rain jacket?” Ultimately, the sense is that short-chain PFCs will be phased out for waterproofness at some point in the future, but until a breakthrough chemistry is found, will remain necessary for applications that need to repel oil and dirt.

Non-Fluorinated Alternatives

Alternatives to PFCs include paraffin, stearic acid-melamine, silicone, dendrimer and nano-material based chemistries (if you are interested, this joint outdoor/sporting goods/fashion industry report outlines the main alternatives). More research is needed to fully determine the environmental fate or health impact of these compounds (and the chemicals used to process them). These alternatives may be biodegradable, but as Jan Beringer comments “Apart from the data we already have on this, there needs to be more research done on how non-fluorine hydrophobic finishes behave in the environment.”

For some, non-fluorinated finishes may provide the protection and performance needed. For others, concerns about the durability and consumer perception remain. Without the oil and dirt repellency, garments may become stained, washed more frequently, or discarded sooner.

In field trials between jackets with non-fluorinated finishes versus fluorinated finishes, Gore found that the everyday grease and grime a jacket may be exposed to—things like food stains, skin oils, sunscreen or even the diesel in road-spray—affects the overall water repellency of a jacket. In these trials, jackets with non-fluorinated finishes lost their water repellency performance faster than those with fluorinated finishes. Gore also performed a life cycle assessment of their waterproof, windproof and breathable jackets in which they found that while production and distribution have an important impact, the longevity of the jacket is the most influential parameter, and the number of washes per year in the use phase plays a significant role. If a waterproof finish affects the longevity of a jacket, and that jacket is discarded earlier by the consumer, then no one wins.

Even though there appears to be good tools in the toolbox for waterproofing, it seems that both research and innovations are needed in this field. Unfortunately, the industry has seen their margins on products go down, and as textile auxiliaries have moved from out of the U.S. and Europe, there have been fewer funds available for research and development. Academic and research institutions could, and in some cases are, taking up this work both in the U.S. and Europe, but much is needed—especially considering the trend towards tailoring recipes and processes for specific applications. New R&D efforts often take six to eight years to come up with a viable new substance and then testing and approval through regulatory bodies can take another two years. So the time frame for change is neither fast nor inexpensive, but it may be inevitable. “Short-chain will be phased out. We need an alternative,” comments Peter Waeber. “As soon as we have one, it’s dead.”

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