The Story of Natural Polymers: From Nature to Knitting Yarn
Natural polymers are large molecules produced by living organisms. They form the building blocks of many materials found in nature, including cellulose in plants, proteins in wool and silk, and natural rubber. In textiles, cellulose is particularly important because it can be used to create both natural plant fibres and regenerated cellulosic fibres.
Cotton, flax and hemp are examples of natural cellulosic fibres, obtained directly from plants. However, cellulose can also be extracted from wood or other plant sources and transformed into textile fibres through industrial processes. This gave rise to a family of materials known as regenerated cellulosic fibres, which includes viscose, modal, lyocell and bamboo-derived viscose.
The development of these fibres began in the late nineteenth century, when researchers sought to create an affordable alternative to silk. Early artificial silk was followed by the development of viscose rayon, which became commercially established in the early twentieth century. Later innovations introduced new production methods designed to improve fibre performance and reduce environmental impacts.
Unlike synthetic fibres such as polyester and nylon, which are generally made from fossil-based chemicals, regenerated cellulosic fibres originate from cellulose, a renewable biological resource. Their final properties depend on the source of the cellulose, the manufacturing process and the structure of the resulting fibre.
For knitting, these fibres offer an appealing combination of softness, breathability, moisture absorption and drape. They are often used in lightweight garments, summer knitwear, linings and fabrics that require a smooth, fluid appearance. However, they can behave differently from cotton or wool during knitting and finishing, particularly in terms of elasticity, wet strength and dimensional stability.
It is important to distinguish between a renewable raw material and an environmentally sustainable finished product. The production of regenerated cellulose may involve significant water and energy use, chemical processing and forestry impacts. Responsible sourcing, efficient manufacturing and chemical recovery systems all play a role in determining the overall environmental footprint.
Understanding how these fibres are made helps knitters select materials that suit both the technical requirements of a project and the qualities they want in the finished fabric.
Viscose: Softness, Drape and Fluidity in Knitting
Viscose is one of the oldest and most widely used regenerated cellulosic fibres. Developed in the late nineteenth century and commercialised in the early twentieth century, it was originally created as an alternative to silk. Its smooth appearance, soft feel and fluid drape made it particularly attractive for clothing and textiles.
The production process begins with cellulose, usually obtained from wood pulp. The cellulose is chemically processed into a soluble form, transformed into a spinning solution and extruded through tiny openings into a chemical bath, where it regenerates into fibres. These fibres are then washed, processed and prepared for textile production.
Viscose is known for its excellent drape, softness and ability to absorb moisture. It often feels cool against the skin and can produce fabrics with a fluid, elegant appearance. These characteristics make it popular for tops, dresses, lightweight sweaters, scarves and other knitted garments where movement and comfort are important.
Viscose can be manufactured as continuous filament or staple fibre. Filament yarns tend to have a smooth, lustrous surface, while staple fibres are spun into yarns with a softer, more familiar textile appearance. Both can be used in knitting, depending on the desired fabric structure and finish.
However, viscose has some limitations. Conventional viscose fibres can lose a significant amount of strength when wet, and fabrics may shrink, stretch or deform during washing and drying. They also tend to have less elastic recovery than wool or elastane-containing yarns. These characteristics make fabric construction and finishing particularly important.
The environmental impact of viscose depends on the sourcing of the cellulose, the chemicals used in production and how efficiently those chemicals are recovered. Conventional production can generate substantial chemical waste if not properly managed, while responsibly sourced cellulose and improved manufacturing systems can reduce some of these impacts.
TENCEL™: Modern Cellulosic Fibres with a Focus on Responsible Production
TENCEL™ is a textile fibre brand owned by Lenzing, an Austrian fibre producer. It is best known for its lyocell and modal fibres, which are made from cellulose sourced primarily from wood. Unlike viscose, which is generally produced using a different chemical conversion process, lyocell uses a solvent-based process designed to recover and reuse most of the solvent.
Lyocell fibres were developed as an alternative to conventional regenerated cellulosic fibres, with the aim of combining desirable textile properties with a more efficient production process. Commercial lyocell became available in the 1990s, and TENCEL™ has since become a familiar name in clothing and home textiles.
TENCEL™ Lyocell is valued for its smooth surface, softness, moisture absorption and drape. Depending on the yarn construction, it can create fabrics that feel cool and comfortable against the skin while maintaining good strength. TENCEL™ Modal is also known for its softness and is often used in lightweight, flexible garments.
These fibres are widely used in T-shirts, underwear, dresses, activewear and knitted fabrics that require a smooth hand and fluid movement. In knitting, their ability to absorb moisture can contribute to comfort, while their surface characteristics can produce fabrics with a refined appearance.
Despite these advantages, lyocell and modal do not behave identically. Their properties depend on the fibre type, yarn construction and finishing. Lyocell generally has good strength, including when wet, but knitted fabrics may still stretch or change dimensions depending on the stitch structure and fabric weight. Smooth yarns may also have different friction and feeding characteristics from more textured fibres.
One of the main environmental advantages associated with TENCEL™ Lyocell is its closed-loop solvent recovery system, which allows most of the process solvent to be reused. However, the overall environmental impact still depends on forestry practices, energy sources, processing and the full product lifecycle. The TENCEL™ name should not be treated as a generic term for all lyocell or modal fibres; it is a trademark for specific branded products.
For knitters, TENCEL™ fibres can be a good option for soft, breathable fabrics with a fluid drape. When selecting a yarn for machine knitting, it is still essential to check the yarn count, ply, twist and surface finish, as well as how the fabric behaves after washing.
Bamboo: From Plant to Regenerated Cellulosic Yarn
Bamboo has gained popularity in the textile industry because it is a fast-growing plant that can regenerate quickly and requires relatively little agricultural input under suitable growing conditions. Its fibres are often associated with softness, breathability and a more natural alternative to conventional synthetic textiles.
However, bamboo textiles require an important distinction: most commercially available bamboo clothing and knitting yarns are not made from mechanically extracted bamboo fibres. Instead, they are made from regenerated cellulose obtained from bamboo pulp, usually processed into viscose or rayon.
To manufacture bamboo-derived viscose, bamboo is harvested and processed to extract cellulose. The cellulose is then chemically converted into a soluble form, spun into fibres and regenerated. The resulting yarn can feel exceptionally smooth and soft, making it popular for lightweight garments, baby clothing, underwear, socks and summer knitwear.
Bamboo-derived viscose generally absorbs moisture well and offers a fluid drape. These characteristics can make it comfortable against the skin, although the actual performance depends on the yarn construction and fabric structure. As with other viscose fibres, fabrics may be prone to stretching, shrinkage or deformation if they are not properly constructed and cared for.
The environmental benefits of bamboo are not automatic. Although the plant can grow rapidly, converting it into textile fibre may involve chemical-intensive processing. Conventional bamboo viscose uses a process similar to other viscose fibres, and its environmental performance depends on chemical management, solvent recovery, energy consumption and the sourcing of the bamboo. Claims that bamboo fabric is inherently antibacterial or always more sustainable than other fibres should therefore be treated with caution.
For machine knitting, bamboo-derived viscose can produce soft, lightweight fabrics with excellent drape. Its relatively low elastic recovery means that stitch structure, fabric density and finishing deserve particular attention when shape retention is important. As with any yarn, checking the actual yarn count, ply, twist and feeding behaviour is more useful than relying on the fibre name alone.
At a glance: Comparing viscose, TENCEL™ and bamboo-derived fibres
| Property | Viscose | TENCEL™ Lyocell | Bamboo-derived viscose |
|---|---|---|---|
| Cellulose source | Usually wood pulp | Usually wood pulp | Bamboo pulp |
| Production method | Regenerated cellulose | Solvent-based lyocell process | Usually viscose process |
| Main qualities | Softness, moisture absorption, fluid drape | Softness, strength and moisture absorption | Smoothness, softness and fluid drape |
| Wet strength | Often significantly reduced | Generally good | Often reduced, as with conventional viscose |
| Common knitting uses | Lightweight garments, tops and dresses | Knitwear, activewear and everyday clothing | Underwear, socks, babywear and summer knitwear |
| Environmental considerations | Forestry and chemical management | Forestry, energy use and solvent recovery | Bamboo sourcing and chemical processing |
An important point for Kniterate machine knitting: regenerated cellulosic yarns can vary considerably in thickness, strength, friction and elasticity. Kniterate generally works best with yarns in the Nm 6–8 range, although suitability depends on yarn construction and the fabric being developed. Smooth filament yarns and staple-spun yarns can behave differently even when they have the same nominal count. Before knitting a full piece, test the yarn at an appropriate stitch size and carriage speed, checking yarn feeding, stitch formation, fabric stability and how the swatch behaves after washing and drying.