In Season This Year: Sweaters from Slaughterhouse Run-off

Rejoice high-end fabric lovers and animal-rights activists, narrow group you may be. A group of researchers from ETH Zurich have found a way to make synthetic Angora wool. Angora wool—not to be confused with mohair which comes from Angora goats—is made from Angora rabbits, a breed of fluffy rabbits (pictured below). It’s exceedingly expensive, about $10 – 16 per ounce, so most commercial yarns are blends of Angora and other, cheaper fibers such as wool.


An Angora rabbit. So cute.

To produce high quality wool, the rabbits must be groomed weekly (or more) as the hairs easily mat. Producers of Angora wool have come under some heat lately for plucking the fur from live animals, which causes pain and distress to the animals.

The faux-fur of the Switzerland researchers is made from gelatin, specifically from slaughterhouses. The gelatin comes from degraded collagen of hides, bones, hoofs, tendons, and horns, most of which is discarded as waste. The gelatin, after it’s cleaned, is mixed in a solution of water and isopropyl alcohol (simple rubbing alcohol) and heated. This creates a 2-phase system with suspended gelatin fibers. The fibers are spun in a dry-spinning process, as depicted below, to form kilometer-length fibers.


The dry spinning process. A solution of the fibers is forced through an extruder/spinneret to form strings of fabric, then dried in the evaporation chamber to remove any solvent.

Angora wool fibers are different from typical fibers in that they have pores. With the two-phase process, the gelatin fibers form with similar sized pores as a result of the water/alcohol mixture getting trapped inside the fibers as they’re formed. In the heating chamber during spinning, the solvent is removed and an empty space is left in the middle. Pores make up about 30% of the fiber.

The only problem is that gelatin is soluble in water, so if these fibers get wet they’ll dissolve. The researchers solved this problem by crosslinking the fibers with formaldehyde and a dehydrothermal treatment, which changes the structure of the gelatin by forming bonds between adjacent molecules. The crosslinked fibers don’t dissolve in water, though they do swell slightly. But the swelling is no more than a human hair swells in water.


a) The gelatin/water/alcohol mixture. Fiber was spun 30 min after preparation from the the opaque phase. After 30 days the mixture degraded and could no longer be spun. b) Gelatin fiber coiled and ready to go. c) Fibers can easily hold a weight of 140 g without snapping.

The crosslinked fibers are as strong as the Angora fibers, as soft, and much easier to make. Instead of raising a hoard of rabbits and meticulously grooming and harvesting their fur, all you have to do is take slaughterhouse runoff, mix it in a heated water/alcohol solution, and spin it into fibers. This is a fantastic eco-friendly solution to high-end animal fabrics. I only hope this method makes it to market so I can get me some waste-wear.

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