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Chemistry, Materials & Packaging
Hong Kong Scientists Developing Cashmere That Can Self-Clean in Sunlight

Scientists at City University, Hong Kong have developed a treatment for cashmere that enables it to self-clean with some help from the sun.

The technology coats cashmere fibers with tiny particles of the mineral anatase titanium dioxide. When exposed to sunlight for 24 hours, the mineral starts a chemical reaction creating oxidants that act as tiny electric currents to break down dust, dirt, bacteria and even trickier stains such as coffee and wine.

"Within 24 hours of daylight exposure, any red wine or coffee stains were gone," said Walid Daoud, assistant professor at the School of Energy and Environment at City University and the lead researcher on the project.

The team have applied the coating to cotton and wool since 2002, but this is the first time it has been tried with cashmere. Daoud added that retaining the softness of the fabric and preventing damage to the delicate fibers from the oxidization process was a "huge challenge."

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Cashmere is expensive to clean. If the project succeeds and is commercialized, it could lead to substantial savings on energy, water, washing liquids and dry cleaning chemicals. Daoud estimates that the price of the treatment would add just 1-1.5 percent to the cost of the fabric’s production, which will easily be made up for by the savings on cleaning.

The technology is still in its infancy and has many questions unanswered – for example, while washing and dry-cleaning does not remove the coating from the cashmere, the fabric hasn't yet been exposed to steam-cleaning or ironing.

"We also have to think about whether sunlight would discolor [the] fabric," says Tommy Siu Yuk-yinn, Senior Research and Development Manager with TAL, a major clothing manufacturer in Hong Kong that has been working with researchers at the Hong Kong Polytechnic University on similar technology. "I think 24 hours is still too long,” he added. “We don't have 24 hours of sunlight in a day. Also, is it OK if it's diffused sunlight? We don't always have direct sunlight.”

If the technology does come to market, it will likely delight our friends at Levi-Strauss, who have been touting the virtues of washing your clothes much less, to save resources and extend the life of garments - at SB ’14 in June, Paul Dillinger, Levi’s Head of Global Product Innovation,asked us to start thinking of the cotton clothes that we buy as houseplants – all they need in terms of care is “a little bit of water, a little bit of sunlight.”


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