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What is Modal ?

Modal in Thermal Underwear


Well this one might surprise you a bit – but the fibre Modal is actually made from trees !  Beech trees to be specific.

Beech tree Leaf


Beech trees are common all over Europe, North America and some parts of Asia – largely in the Northern hemisphere.   They are easily recognisable by the shape of the leaf – which has a slightly waxy feel to it.

Historically the most common use of the Beech tree has been in firewood.  However, as the wood is easily pulped it was often used as the base material for early types of papers.  In fact, you probably won’t realise, that the word “book” even comes from the Olde English for Beech Tree.


Modal is a type of Rayon


Modal has been in production for almost 60 years, since it was invented in the 1960s in Austria by Lenzing AG, and Austrian chemical company.

Rayons are a group of fibres that are made from processed wood pulp.  The wood pulp is first purified, then chemically converted into a soluble compound.  This is then dissolved and spun into a fibre.  There are many different types of Rayon – you will probably be familiar with many of the names including Viscose, Lyocell  and Modal.

Modal is a Rayon but is slightly different as it is made exclusively from the reconstituted cellulose from Beech wood pulp, rather than other wood pulps.


Natural or man-made ?


Although the core basic ingredient of Modal (Beech Wood) is natural, Modal is considered a”bio-based” product as during the production process it is heavily processed using chemicals.  Nowadays almost all the chemicals used in the processing are re-cycled – so it does rather improve the green credentials of the fibre.


Properties of Modal


Modal was originally marketed as “artificial silk”.  The fibre is extremely soft  and gives a really luxurious soft feel to a fabric.   From a clothing perspective Modal:

  • drapes very well, giving well fitting garments that look great when worn
  • is far more shrink and pill resistant than cotton
  • holds dyes really well and is therefore less lightly to fade


 Why is Rayon used in Thermal Underwear ?


Rayon is a great fibre to use in thermal underwear.  It is a soft, almost silky, fibre which feels very comfortable when worn directly contact with the skin – ideal for use in underwear.  Rayon is also 50% more water absorbent than cotton (on a weight for weight basis) – so it is able to “wick” moisture away from the skin.  Dampness is one of the main reasons clothing loses its thermal insulation, so this will help you stay dry and warm.

Although the fibre itself does not have the thermal insulation properties of wool, it is often mixed with more insulating fibres to produce an extremely comfortable garment.  This is particularly important for anyone with a wool allergy, who still wants to wear a natural based, rather than fully man-made, product.

You can take a look at my range of Modal based thermals by clicking here.