Silk from America as a substitute for polyester?


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Would it be possible to replace polyester fibers from petroleum with fibers from the common milkweed that grows here and is called Quebec cotton? This is the question posed by one of our readers, Denis Carrier. The answer: yes and no. In fact, the question raised deserves a more detailed and nuanced answer, given the very specific properties of this wonderful plant, also called “American silk”.

You should first know that milkweed grows naturally in Quebec and is essential to the reproduction cycle of the monarch butterfly, an endangered species that migrates to Mexico to spend the winter. This plant has recently become known for the insulating and water-repellent potential of the long white bristles contained in its elongated fruits. The properties of this silk have aroused the interest of outdoor clothing manufacturers for several years, who see this fiber as a more ecological and effective insulator than polyester or down to face the cold season.

“Yes, milkweed fiber has all the qualities to replace polyester as synthetic insulation in outdoor clothing. The problem is that due to its high volatility, it must first be integrated into a membrane in order to be sewn to a garment. To weave it, you would have to stick the fibers together with a binder, and then you risk losing its insulating and water-repellent properties,” explains Annabelle St-Pierre, researcher at the Innofibre cellulosic products innovation center at the Cégep de Trois Rivières.

An insulator, but not a fabric

The silky character of this all-Quebec fiber therefore has a downside. Ultra-smooth, it cannot be woven to produce other types of textiles. “If we are talking about clothes to wear every day on the skin, the fiber is too short and too slippery to make a textile suitable for producing a fabric. That’s why it’s mainly used as an insulator,” she adds.

For the moment, the “silk of America” ​​is therefore used as insulating material inside clothes, mittens or blankets, confirms Laurence Gaudy, co-founder and head of technical development at Atypic, a start-up that manufactures clothes. outdoor and blankets insulated with milkweed fiber.

When compared to insulators made of polyester foam on the market (Primaloft, Primalight, etc.) or down, silk from America, a natural insulator, wins almost across the board. Its insulating capacity in extreme cold was also successfully tested during an expedition to Mount Everest carried out in 2016 by Quebec mountaineer Jean-François Tardif.

“Pure milkweed fiber is warmer, more water repellent. And, unlike down, it remains insulating once compressed. It is also antimicrobial, which is not the case with polyester, conducive to the development of bacteria that attract odours,” adds Laurence Gaudy.

That said, the silky fiber remains very expensive, because the harvest of its pretty white egrets is still done in an almost artisanal way and total production in Quebec remains too limited to meet sustained demand. The process used to stabilize milkweed in textiles is still laborious.

“Right now, there is also a market problem, maintains Annabelle St-Pierre, because it is difficult to compete with polyester produced at low cost in India or China. It’s still difficult to produce low-cost clothing with milkweed insulation,” says Annabelle St-Pierre.

However, the very young outdoor clothing company Atypic persists in promoting this local and ecological insulation, produced without fertilizers and without water. “Milkweed insulation costs four or five times more than an ordinary polyester roll, but we want to attract people who are looking for a quality, eco-responsible, fair trade and entirely plant-based product,” maintains Laurence Gaudy.

To stabilize the milkweed fiber’s volatility, the company blends this silky fiber with 30% kapok fiber (another longer-fibered plant), with an organic binder made from corn starch, which provides stable insulation that can be more easily trimmed and incorporated into various garments and outdoor products. Without this process, the fiber would quickly disperse inside the garment and clump together in small piles. Unlike down, compressed silk finds its shape more difficult once compacted, explains the co-founder of Atypic.

In short, American silk has quite a future in the specialized outdoor world, where it can replace petroleum-based insulators. But unless there are innovations in transformation processes, it is not tomorrow the day before that milkweed will damn the pawn of polyester in wardrobes.

Until then, we can hope for its proliferation in our mittens and our anoraks, as well as in the fields, where its pretty flowers play a major role in our ecosystem by rendering great services to the monarchs.

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