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A good yarn: time up 
for cashmere ripoffs

December 16, 2009

MORIOKA, Japan — Japanese researchers have developed a device that can measure cashmere fabric purity via electromagnetic radiation, a finding that could help reduce the time and cost involved in checking whether cashmere products are accurately labeled.

According to the researchers, the device can quickly detect whether wool and other fibers have been mixed with cashmere by vibrating the fibers at the molecular level and emitting terahertz waves.

The research team at Iwate Prefectural University is led by Prof. Toru Kurabayashi , 52, a specialist in electronics.

According to Kurabayashi, each fiber oscillates at a different wavelength and intensity after being bombarded with terahertz waves, enabling each strand of material to be distinguished individually. "It's like identifying people through their fingerprints," Kurabayashi said.

The study group began the research after a request from a major cashmere distributor to develop a way to easily distinguish cashmere and other fibers.

The team studied oscillating waves of about 30 fibers, including cashmere, wool, cotton, acrylic and nylon. Because each fiber has a distinctive wave, the group was able to discern between cashmere and wool, which have similar textures.

Cashmere, which is known for its soft texture, is produced by weaving downy hairs of the cashmere goat. Because the goats yield only about 200 grams of cashmere, the fiber is highly sought after.

Many "cashmere products" that actually contain wool and other fibers are passed off as genuine cashmere products.

People in the cashmere industry say the volume of "cashmere" products circulating on world markets is four times larger than the fiber's true production volume.

The Japan Wool Products Inspection Institute Foundation uses a microscope to inspect fibers from cashmere products one by one after extracting them from the products. However, each product takes an hour and costs more than 15,000 yen to check, a toll that causes furrowed brows among wholesalers and distributors.

The device is about two meters long and one meter wide. The study group's next task is to downsize the device, Kurabayashi said.

"By using the device, users can check the purity of cashmere products accurately in several tens of seconds, which enables companies to cut costs significantly. The next step is to put the device to practical use. We want to develop small devices by collaborating with the private sector."

Terahertz waves have a frequency range of 0.1 to 10 terahertz. The frequency is lower than the frequency of light waves, but higher than those of radio waves.

Junichi Nishizawa , former president of the prefectural university, devised a method to generate terahertz waves about 40 years ago. In the future, the waves are expected to be used during checks for gunpowder, narcotics and food additives that cannot be detected by X-ray.

 



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