Natural Synthetic Yarns - Tencel, Modal, Rayon, & Viscose

No, that is not a typo!

Most of us have heard of the two main types of yarn: natural and synthetic. These two yarn types are characterized by not only what they are made of but also how they are made. These yarns also have subcategories that further characterize them (protein, cellulose, etc.) and help to start understanding what they are used for.

So what happens when you have a yarn that is made from a natural material but created with a synthetic process?

You probably guessed it: natural synthetics.

In our ongoing journey to understand the yarns that we weave with it is time to go over yarns like Tencel, modal, and rayon.

These yarns are often touted as the yarns of the future because they have the best characteristics of both worlds. This is not always the case, though.

Also, it is important to admit that this is not as clear-cut an article as you would imagine. It is not uncommon for these yarn names to sometimes be used interchangeably and for things to get a bit complicated.

Before we go on – here are my other yarn guides in case you missed them:

Weaving with cotton

Weaving with linen

Weaving with hemp

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By any other name (viscose)

When searching for yarns like these you may also come across different descriptors that all really mean the same thing. These names are: semi-synthetic, regenerated cellulose, and plant-based synthetic.

Speaking of alternate names: the term viscose can be used for any and all types of these natural synthetics, but it is mostly used as an alternative name to rayon. Since it is sometimes used for any natural synthetics, though, it means viscose could either be “good” or “bad”. Natural synthetics are often touted as being sustainable, but that is not quite the full story. So while the generic term viscose could be a good sign, it does not necessarily bode sustainable.

Viscose itself is considered the first generation of natural synthetic fibers so it is understandable that it has become a term associated with all of them. Think of it as the fiber version of Kleenex or Xerox. Those are brand names that are applied to other similar products.

The generations of natural synthetic fibers essentially shows where these fibers sit in the grand scheme of innovation. With each new generation of yarn the process has gotten cleaner and more sustainable.

Just like viscose, the term rayon can also be used as a catchall. The issue with this is that other types of natural synthetics have their own names and their own processes for creation. Some of them are cleaner than others. Using the term rayon to cover all of these fibers makes it hard to distinguish the good from the bad (so to speak.)

Remember that thing you learned in geometry where a square is a rectangle but a rectangle is not always a square? It is kind of like that.

So viscose could be the same thing as rayon and rayon and viscose could also be used to describe other types of natural synthetics…

Remember I said it gets confusing?

How natural synthetics are made

While all of the different types of natural synthetics are going to be a little different in the way they are made, they are all generally made with the same process.

The long story short version goes like this: first, raw materials (plants) are broken down into small pieces with different chemicals. This creates a viscous pulp of raw cellulose (where the original term viscose came from.) This pulp is then extruded through a machine with high pressure to create a fiber that will be spun into yarn.

The biggest difference is what happens to all those chemicals after the yarn is created.

Environmental impact of open and closed-loop systems

When it comes to the production of just about anything there are two types of systems that determine what happens to the byproducts from the creation process.

These are open-loop and closed-loop systems.

Open-loop production systems are those that create the product and anything that is leftover (chemicals) gets discarded. These chemicals then are possibly released into the environment.

Closed-loop systems on the other hand take those leftover chemicals and reintroduce them back into the manufacturing process. This means less waste and no negative consequences for the environment.

Rayon (from bamboo)

Despite one of the previous statements above that rayon is a generic term for natural synthetics, we are going to use the term to mean a synthetic yarn made from bamboo as this is the most common way that rayon is made.

Rayon (just like viscose) is considered a first-generation regenerated cellulose fiber.

Rayon is probably one of the most commonly used natural synthetic yarns that you will come across. In fact, I guarantee if you take a look through your own closet you will probably have at least a few articles of clothing made with rayon.

If you are not new to the sustainable journey, then you probably already know that bamboo in and of itself is a very eco-friendly material due to the fact that it is fast-growing and requires little to no pesticides.

Bamboo is used to make a lot of different products from toothbrushes to toilet paper to flooring. When it is used to make yarn, though, it has to go through an extensive process to create the shiny and durable yarn that we are all used to.

As stated earlier, the process of creating rayon takes raw bamboo that is turned into a pulp through the use of chemicals. Unfortunately, the chemical (carbon disulphide) used in the rayon process is considered a neurotoxin and is dangerous not only to the people that are making the fabrics, but also to the environment. Rayon is created in an open-loop system which, if you remember, means those toxic chemicals are leaching back into the earth.

The creation of rayon is so toxic that the production of certain types of rayon has actually been banned in the United States.

The rayon that I am using is 8/2 Maurice Brassard Bamboo in cactus.

Vegan (artificial) silk

One of the biggest draws to rayon is that it is often deemed a vegan silk alternative. This is because of its high luster and great drape. If you are someone that does not like to use any animal products then this could be a great option. That being said, harmful for the environment generally also means harmful to the animals that live there.

Tencel and modal are also considered silk alternatives and they are potentially better for the environment. The result of these yarns are very similar to that of rayon as they create a high luster yarn with a great drape.

So why would you choose one over the other? One of the biggest reasons may be price, followed by not enough knowledge of what either or both are made of. Due to the different chemicals needed and their somewhat different productions, Tencel (for example) tends to be a little more expensive than rayon.

If you are just after the sheen, you can also consider mercerized cotton. You can learn more about mercerization in this post on yarn treatments and specialty yarns.

Once again, Modal is not so straightforward. Modal, in general, is a second-generation cellulose fiber that is created with beech trees.

Generic modal can be considered sort of a middle ground between rayon and Tencel. (Tencel is next!) While it uses the same neurotoxin: carbon disulphide that is used in the creation of rayon, it uses less of it. The process of modal creation also employs a catch system that is intended to lessen the leaching of this chemical into the environment.

Hope for modal, though, is not lost. There is a version of modal by the Austrian company Lenzing that is called TENCEL ™ Modal. This type of modal is created with patented technology that traps even more chemicals – keeping them from the environment. They also only use beech trees that are sustainably grown.

The issue with other types of modal is that this same sort of transparency is not there. Other companies do not disclose where they are getting their resources and you could be inadvertently purchasing yarn made from non-renewable sources.

As far as the benefits of modal, they are similar to that of other regenerated cellulose yarns. In fact, modal tends to be even softer and more breathable than Tencel.

A downside, though, is that it is hard to find yarn that is purely modal as it is often mixed with other yarns like cotton. So if you are looking for a yarn that is purely made from modal then, at least at this time, you will have a hard time finding it.

Tencel (Lyocell)

Tencel and lyocell can be one and the same. Where lyocell is the generic fiber – Tencel is actually the brand name that is made by Lenzing (just like modal.)

Tencel is made solely with eucalyptus. This eucalyptus is grown and sustainably harvested. Plus eucalyptus requires little water and no toxic pesticides to grow! That makes it a great choice for a sustainable fiber base.

Lyocell on the other hand can be made with eucalyptus, oak, or birch trees.

Unlike rayon, Tencel and lyocell are created in a more sustainable and conscientious closed-loop system. The chemicals used are also less toxic and continue to be recycled and reused over and over.

Pros and cons of Tencel (lyocell)

As far as sustainability goes, beyond the points we already mentioned, Tencel is also completely biodegradable. That means that when your fabric is no longer of use, or if you have yarn scraps that you do not know what to do with, then you can rest assured that they will not be stuck hanging around a landfill.

Do you know what to do with your yarn scraps? Ideas here!

When it comes to weaving, Tencel is soft, strong, and is prized for the way it holds dye. This high absorbency translates well to practical uses as it is 50% more absorbent than cotton!

The biggest disadvantage is that it tends to be more expensive than some of the other options. Unfortunately, you often have to pay for sustainability.

The tencel that I am using in this post is 8/2 Maurice Brassard Tencel in colors vieux blue, charcoal, and navy.

natural synthetic yarns infographic generations

Different weavers will always have different concerns about their yarns and other materials. Vegan and plant-based may be important to some people and not even a consideration for others. Those looking for vegan options may choose synthetic yarns more often, and those who are sustainably minded may opt for only natural (protein or cellulose) yarns.

Of course, when you are trying to keep in mind both, or you are just looking for some more options, the natural synthetics like rayon, modal, and Tencel can all seem like a great option.

It is important to know where your materials come from and understand the impact they have and not only your weavings, but also the people who make them, and the world we live in.

Despite the confusing interchangeably used terms it can be possible to make a choice that you are happy with. If you are wanting a fiber that is more sustainable stick with those that are labeled Tencel, lyocell, or modal. That way you always know what you are getting instead of being left to wonder.