Wood Pulp based FR fibers and its differences

Comparison of Tencel, Lyocell, Viscose, Modal fibers.

Wood Pulp

Tencel is simply a brand name of a type of Generic lyocell. Tencel/lyocell are both wood-based cellulose fibers, both made from wood pulp. Tencel however, is made from wood pulp and Lyocell, is instead usually made from bamboo pulp. As we know, Lyocell is produced using a closed loop system which has minimal impact on the environment and maintains economical use of energy and water. This is the same process as Tencel however as a base product bamboo plants require far less water to grow than other trees, making it a more sustainable fabric. Tencel can often be mixed with other fabrics such as cotton or rayon and is also generally 20-30% more expensive than Bamboo Lyocell.

OK, so tencel and lyocell are both plant-based. So how are they different from Viscose and Modal?

The differences between viscose, modal and lyocell are subtle. It comes down to the manufacturing process and structure of the filament. Viscose and modal are made using a very similar process with similar chemicals used at each stage of production. Viscose production has been continuously refined over the past 100 years to make a textile which is soft yet easy-care. However, modal fibres are treated slightly differently after spinning to make the filaments stronger. For example, the fibres are also stretched to increase molecular alignment. This means that modal fibres have the potential to be lighter and finer and can be tumble dried without damage. Other than that viscose and modal are similar products. Lyocell is still the same plant-based fibre as viscose and modal, but it is made using a slightly different process. Lyocell production uses a different solvent to extract the cellulose from the wood: sodium hydroxide (caustic soda) is replaced by a non-toxic organic compound with the catchy name N-Methylmorpholine N-oxide (NMMO for short). This organic solvent is easier to filter and re-use in a closed loop, which is better for the environment. The Austrian firm Lenzing go a step further by only making their lyocell, branded as Tencel®, from fast-growing Eucalyptus trees from sustainably managed forests.

Microscopic view of fibers

So they are all fairly similar then? Yes. Viscose, modal and lyocell are very similar – so much so that you might be forgiven for calling them all viscose. The important thing to remember is that they may be man-made but they are not synthetic. In fact, as fibres that are man-made from a natural product, we might call them semi-synthetic fabrics.