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Viscose vs. Modal vs. Lyocell - Difference?

Robert Kay

Posted on April 30 2017

Written by Robert Kay
Co-founder and designer

You've probably heard of all three fibres. You may even be wearing a version of one now. But do you know what they are? In this article we take a spin over the similarities and differences of viscose, modal and lyocell.

Viscose, modal and lyocell are all made from plant material.

That's right, viscose, modal and lyocell are all made from plants, typically trees, but it could be soybeans, bamboo grasses, or even cotton plants. They are all variations of the same fibre generically known as viscose in Europe and rayon in North America. Scientifically they are described as regenerated cellulosic fibres. That means they are composed of cellulose (a compound which gives plants their stiffness) that has been extracted, dissolved and then realigned to make a fibre. So, despite being man-made, the fibre itself is composed of long chains of cellulose molecules that have been lined up to make a useful filament (very long continuous fibre), not unlike silk. This plant-based chemical structure is what gives these textiles their desirable properties, such as a natural next-to-skin softness, breathability and good moisture management.

Does that mean these fibres are synthetic, like nylon or polyester?

No. Viscose fibres may be man-made, but chemically they are still plant-based and therefore not synthetic. That's what sets viscose apart from nylon or polyester, both of which are made from petroleum derived compounds that do not naturally occur and are therefore fully synthetic. Synthetic fibres do not have the same breathability or moisture management properties, which is why they have quite different uses. Why? It comes down to the chemistry of the base compounds and how they react with water.

The naturally occurring cellulose compound is attractive to water (they are said to be hydrophilic). Water molecules 'wet' the fibres and even penetrate into micro pores inside the fibre structure. This is why viscose, modal and lyocell are all water absorbing fabrics. This affinity to water (and water vapour) is what helps to make these fabrics so breathable.

In contrast the compounds that are used to make nylon and polyester are not attracted to water (they are said to be hydrophobic). In just the same way that oil won't mix with water, nylon and polyester fibres don't attract water molecules. Instead of 'wetting' the fibres water pools on the surface of the fibre with no internal penetration. This gives nylon and polyester very different properties: these fabrics are excellent at wicking moisture away precisely because the water stays on top of the fibre. A close weave will also trap water, water vapour and heat making some nylon or polyester fabrics hot and clammy to wear (an experience you won't forget if you ever had to wear a cheap Polyester uniform on a hot day).

If you want to know more about moisture absorbing and moisture wicking you can find out more in this article written by Yvonne. Or, if you'd like more detail about how the chemistry of fibres determines how they interact with water you can read more in this article.

OK, so viscose, modal and lyocell are all plant-based. So how are they different?

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.

Picture of a eucalyptus tree

A Eucalyptus tree

The end product of Lyocell is still plant-based, just like viscose and modal, with the same natural feel and desirable properties. As well as this, a byproduct of the different production method is that the internal structure of the fibre is more uniform which further improves its ability to absorb water.

In the image below the internal structures of Tencel® (lyocell), modal and viscose are seen under an electron scanning microscope. The dark areas are where water has been absorbed into the micro-pores of the fibres: you can see clearly that the absorption of the water in Tencel® is more uniform. This internal structure is a product of the different manufacturing process and gives fabrics made from Tencel® improved moisture absorbency and breathability.

Pictures of celluslose based fibres under an electron scanning microscope. The dark areas show water absorbed into the structure of the fibre. Picture Lenzing Fibres

Pictures of celluslose based fibres under an electron scanning microscope. The dark areas show water absorbed into the structure of the fibre. Picture Lenzing Fibres

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.

Right now we use viscose made from bamboo for our undershirts. Not only does it feel amazing on your skin (all day long), it also: absorbs your sweat; regulates your body temperature; and protects your shirts from deodorant marks. It's the perfect technical base layer for the office, and we think it helps make the best undershirts.

See how wearing an undershirt can protect your shirt and give you a more finished look.

ROBERT OWEN UNDERSHIRTS

"It is so comfortable I forget that I'm wearing it"
- Chris H

You've probably heard of all three fibres. You may even be wearing a version of one now. But do you know what they are? In this article, we take a spin over the similarities and differences of Viscose, Modal and Lyocell.

Viscose, Modal and Lyocell are made from plant material

That's right, Viscose, Modal and Lyocell are all made from plants, typically trees, but it could be soybeans, bamboo grasses, or even cotton. They are all variations the same fibre, which is generically known as Viscose in Europe and Rayon in North America. Scientifically they are described as regenerated cellulosic fibres. That means they are composed of cellulose (a compound which gives plants their stiffness) which has been extracted, dissolved and then realigned to make a fibre. That sounds simple on paper but trust me it's not. None-the-less despite being man-made the fibre itself is composed of long chains of the cellulose molecule lined up to make a useful filament (very long continuous fibre), not unlike silk. This plant-based chemical structure is what gives these textiles their desirable properties of natural skin feel, breathability and good moisture management.

Does that mean these fibres are synthetic, like Nylon or Polyester?

No. Viscose fibres may be man-made, but chemically it is still plant based and therefore not synthetic. That's what sets it apart from Nylon or Polyester which are fully synthetic made from compounds derived from petroleum and not naturally occurring. Synthetic fibres do not have the same properties of breathability or moisture management, which is why they have quite different uses. Why? It comes down to the chemsistry of the base compounds and how they react with water.

The natuarlly occuring cellulose compound is attractive to water (they are said to be hudrophilic). Water molecules 'wet' the fibres and even penetrate into micro pores inside the fibre structure. This is why Viscose, Modal and Lyocell are all water absorbing fabrics. This affinitiy to water (and water vapour) is what helps to make these fabrics so breathable.

In contrast the compounds that are used to make Nylon and Polyester are not attracted to water (they are said to be hudophobic). In just the same way that oil won't mix with water, Nylon and Polyester fibres don't attract water molecules. Instead of 'wetting' the fibres water pools on the surface of the fibre with no internal penetration. This gives Nylon and Polesyter very different properties. These fabrics are excellent at wicking moisture away precisly because the water stays ontop of the fibre. It also means water can be trapped by a close weave, which also traps water vapour and heat making some Nylon or Polyester fabrics hot and clammy to wear (an experience you won't forget if you ever had to wear a cheap Polyester uniform on a hot day).

If you want to know more about moisture absorbing and moisture wicking you can find out more in this article written by Yvonne. Or, if you'd like more detail in how the chemistry of fibres determin how they interact with water you can read more in this article.

OK, so Viscose, Modal and Lyocell are all plant-based. So how are they different?

The difference 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 using the similar chemicals 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. The difference is that Modal fibres are treated slightly differently after spinning (for example stretching them to increase molecular alligment) to make the filaments stronger. That means that Modal fibres can be lighter and finer and they 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, or 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 making their Lyocell, branded as Tencel®, only from fast-growing Eucalyptus tree from sustainably managed forests.

Picture of a eucalyptus tree

A Eucalyptus tree

The end product of Lyocell is still plant based, just like Viscose and Modal with the same natural feel, and desirable properties. A byproduct of the different production method is that the internal structure of the fibre is made more uniform further improving its ability to absorb water.

In the image below the internal structures of Tencel® (Lyocell), Modal and Viscose are seen under an electron microscope. The dark areas are where water has been absorbed into the micro-pores of the fibres. You can see clearly how the aborption of the water in Tencel® is more uniform. This internal structure is a product of the different manufacturing process and gives fabrics made from Tencel improved moisture aborbing and breathability.

Pictures of celluslose based fibres under an electron scanning microscope. The dark areas show water absorbed into the structure of the fibre. Picture Lenzing Fibres

Pictures of celluslose based fibres under an electron scanning microscope. The dark areas show water absorbed into the structure of the fibre. Picture Lenzing Fibres

So they are all fairly similar then?

Yes. Viscose, Modal and Lyocell are very similar. You might be forgiven for calling them all Viscose. The important thing to remember is they may be man-made, but they are not synthetic.

Right now we use viscose made from bamboo for our undershirts. Not only does it feel amazing on your skin (all day long), it also: absorbs your sweat, regulates your body temperature and protects your shirts from deodorant marks. It's the perfect technical base layer for the office. We think it helps to make the best undershirts.

See how wearing an undershirt can protect your shirt and give you are more finished look.

ROBERT OWEN UNDERSHIRTS

"It is so comfortable I forget that I'm wearing it"
- Chris H

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