- Milk fibers are produced from casein proteins and were popular in the 1940s–50s as alternatives to wool.
- It takes approximately 100 pounds of milk to produce 3 pounds of milk fiber.
- Milk fiber clothing and textiles are regaining some interest by manufacturers and consumers looking for environmentally-friendly alternatives to less sustainable fabrics.
A cow, a milkmaid, and a chemist walk into a bar… or a laboratory? Not quite the typical start to a joke, but this is how a 1950s brochure described a then-popular—and somewhat revolutionary—milk fiber textile called Aralac. Between World Wars I and II, wool was scarce and this milk fiber-blended fabric was becoming a go-to substitute for shirts, ties, and other accessories and clothing in the U.S. and Europe. For a moment in time, it seemed that the future of fabrics was milk-based. So why are we not wearing—and maybe not even aware of the existence of—milk fiber clothing now? The answer lies where economics and science intersected in the mid-twentieth century. But like so many things, it seems that history is bringing us full-circle, and the interest in milk fibers has been rekindled in recent years.
Futuristic Fiber in the Past
Milk fiber was originally created by Germans during World War I, when the hard film left by dried milk was mixed into solutions and then spun to form fibers. But these first fibers, and the textiles made from them, were brittle and hard and so were of little practical use. But the idea of using milk to make fiber had been sparked, and in the 1930s, Italian chemist Antonio Ferretti tried to improve upon the first design. His fibers were much softer, and had a wool-like texture and quality, and he sold his patents to an Italian company that produced milk-based fibers under the trade name of Lanital .
In the U.S., production of milk fibers was developed further by Aralac, Inc., a company affiliated with the National Dairy Products Foundation, which later became Kraftco . It seems that making fibers and fabrics was a kind of side project for the growing dairy company, but as wool fiber production declined during World War II, Aralac wisely found an economic niche for its milk fiber fabrics and textiles. A promotional brochure produced by the company itself in the 1950s compares the product to wool and other “natural” fibers, claiming “Aralac is the registered trade mark [sic] for the first chemically stabilized protein fibre to be produced by man” . Advertisements found in Life Magazine in 1944–45 chronicle the use of Aralac in blended fabrics, including “gabardines, twills, flannels, serges, challis and fleeces, as well as in crisp, cool, summer-weight materials in apparel for men, women and children” . The company emphasized both the physical qualities of the product (e.g. its texture and versatility) as well as its novelty: “Aralac is one of the wonders of the future… the promise of a richer, more wonderful tomorrow… but here today for your enjoyment!” . Yet by 1960, Aralac had virtually disappeared from the market, unable to compete with cheap and easy-to-produce synthetics like nylon.
The Cow, the Milkmaid, and the Chemist
Producing milk fiber can be, perhaps paradoxically, both resource-intensive and ecologically-friendly. In its own brochure mentioned above, Aralac, Inc. described the production of it as the collaboration of “the cow, the milkmaid and the chemist … Out of this understanding grew the research and experiments which enabled the technician to change the casein of skimmed milk into a modern textile fibre” . Caseins are among the most prevalent proteins in cow milk—comprising about 80% of its protein content—and they provide essential amino acids to millions of global consumers via dairy products. Other surprising and historical uses for casein include as adhesives and bases for paint, and more recently in edible films for food.
Making casein-based fiber begins with skimmed milk, which is often a non-consumable by-product in dairy production [1,3]. The milk is treated with acid, which results in a coagulated curd that is then washed, dried, and ground into a fine powder. Thirty-five liters of skimmed milk produce 1 kilogram of casein . The casein is dissolved in caustic soda, ripened, and then filtered and de-aerated, which results in the casein becoming a kind of linear macromolecule structure . The fiber is produced through a wet spinning technique, which includes pumping the casein solution at high pressure through a spinnaret—a kind of metal filter that may look a bit like a showerhead—with thousands of tiny holes [1,6,7]. The solution, streaming through these holes, is immersed in an acid and water solution. The acid neutralizes the alkali that dissolved the casein and the small fibers are then stretched and spun [1,6]. Additional processing to remove impurities, strengthen, bleach, and soften the fibers may be done with various additives and chemicals. It is also possible to blend casein fiber with natural fibers like wool, cotton, and silk.
Milk fiber contains as many as 18 amino acids, and has a pH of 6.8, which is the same as the pH of human skin. Some claim that the “natural protein humectant factor” of casein is preserved in milk fiber fabric, and so wearing it is actually good for the health of skin . It is known to be comfortable and anti-bacterial; it is moisture-absorbent, permeable, and heat-resistant. It feels lightweight and silky and is biodegradable . But it takes about 100 pounds of milk to make 3 pounds of milk fiber, which leads some to question whether it is truly an efficient enough product to be considered truly “eco-friendly.”
Back to the Future
Today, milk fiber is (re)gaining interest and popularity as manufacturers and consumers look for alternatives to synthetic materials for clothing and accessories. Recent studies reveal that many mass-produced fabrics contain microplastics that can be released into watersheds and ocean waters during production and washing . So various companies around the world are turning to milk as a potential source for making fibers and textiles that may not leave such a hazardous mark when produced and used. But whether milk fiber products will find enough of a market share to make an environmental impact remains to be seen.
Consumers like the idea of milk fiber clothing, and companies like QMILK in Germany and Swicofil in Switzerland continue to innovate and refine their production techniques. Yet clothing produced from milk fiber is said to lack durability and is highly susceptible to wrinkles. It is also costly to manufacture, and thus is not (yet) an option for most mainstream shoppers . But like most products, demand and supply may help with cost and availability over time, and it may not be too long before we find ourselves milk fiber-based clothing.
1. Chauahn N, Arya N, Sodhi S. Fiber from milk products – a new dimension. Int J Curr Microbiol app Sci 7(04): 1257-1264.
2. DuBois, S. Fortune 500 Inaugural Class: Where are they now? May 6, 2013. http://fortune.com/2013/05/06/fortune-500-inaugural-class-where-are-they-now/
3. Cow, Milkmaid & Chemist. Aralac protein brochure. 1950s. https://www.amazon.com/Milkmaid-Chemist-ARALAC-Protein-folder/dp/B00EV7OCT8
4. Aralac. You’ve heard about it… you’ve seen it… you’ve worn it… but what is it?” Life Magazine, May 22, 1944 pp. 94. https://www.originallifemagazines.com/product/life-magazine-may-22-1944/
5. Aralac. The amazing new protein fiber… a page from the story of tomorrow. Life Magazine, June 18. 1944. pp. 105. https://www.originallifemagazines.com/product/life-magazine-june-19-1944/
6. Muthu, SS (Ed). Roadmap to Sustainable Textiles and Clothing: Eco-friendly Raw Materials, Technologies, and Processing Methods. Singapore: Springer. 2014.
7. Lei S, Chen J, Meiling Z. A study of wearabilities of milk protein fiber fabric. J Appl Sci Eng Innov 4: 141-143.
8. Kiron, MI. Manufacturing process of milk fiber. Accessed 2-17-19. https://www.fibre2fashion.com/industry-article/7106/manufacturing-process-of-milk-fiber?page=2;;;;;;
9. Henry B, Laitala K, Klepp IG. Microfibres from apparel and home textiles: Prospects for including microplastics in environmental sustainability assessment. Sci Total Environ 2019 Feb 20;652:483-494.
Original image published: https://www.interweave.com/article/weaving/yarn-lab-milk-fiber/
Dr. Katie Rodger
SPLASH!® milk science update