As the world becomes more conscious of the environment, we see a rise in popularity of eco-friendly fabrics like Tencel. Tencel is light, versatile, and used in everything from casual wear to underwear to activewear. It’s been lauded as being more sustainable than cotton but it’s a semi-synthetic fiber. Is it biodegradable like natural fiber or will it hang out in our land fills until dooms day?
As it is made from wood pulp, Tencel fibers are 100% biodegradable under industrial, home, soil and marine conditions. However, it biodegrades much slower than cotton or rayon with a half-life of 94 days. If Tencel is blended with synthetic material like nylon and polyester, it won’t biodegrade.
Why does Tencel biodegrade?
Tencel has the ability to fully revert back to nature because it i’s made from a natural source – wood pulp. Even though it is processed with chemicals, Lenzing, the company that produces Tencel, assures us that Tencel is certified as compostable and biodegradable.
However, if Tencel fibers are colored with synthetic non-biodegradable dyes or blended with non-compostable material like nylon, polyester or spandex, the fabric is not biodegradable.
How quickly does Tencel biodegrade?
How quickly Tencel biodegrades depends on the surrounding environment. Fabric degrades most rapidly In warm, moist soil that is well-aerated. In this environment, Tencel was found to biodegrade over short months. A study showed that Tencel was half-way to being fully decomposed at 94 days.
To put this into perspective, rayon has a biodegradation half-life of 22 days and cotton, 40 days. This means, it takes Tencel 4 times as long to decompose compared to rayon and twice as long compared to cotton.
Keep in mind, this is under optimal conditions. In real life, it probably takes a whole lot longer for Tencel to fully return to nature.
Which Tencel fabrics are biodegradable?
Another problem with theoretical scenarios is that it is usually not the case in real life. Almost all Tencel apparel is blended with other types of fibers to form a fabric-blend.
Depending on what type of fiber Tencel is blended with, it might not be biodegradable at all.
This table lists the types of Tencel fabric blends that are biodegradable and those that are not:
| Biodegradable Tencel fabric | Non-biodegradable Tencel fabric |
| Tencel lyocell | Tencel-elastane |
| Tencel modal | Tencel-nylon |
| Tencel denim | Tencel-polyester |
| Tencel-cotton | Tencel-acrylic |
| Tencel-silk | |
| Tencel-cashmere | |
| Tencel-wool | |
| Tencel-linen |
Even if a piece of clothing is made of 100% Tencel, if it is dyed with non-biodegradable dye or sewn with non-biodegradable thread, it will have trouble decomposing.
90% Tencel 10% silk = heavenly soft
What to do with non-biodegradable Tencel blends?
Unfortunately, the technology to sort and separate different fibers from a piece of cloth is still young, inefficient and very expensive. It’s not possible to biodegrade or recycle Tencel-blends.
This doesn’t mean there is nothing you can do about it.
- Upcycling is one of my favorite activities. Can you repair or modify it so you would want to continue using it?
- If you can’t find a reason to keep it, donate it. Giving away used clothes is a good way to prolong their lifespan. And anything is better than throwing it away to pile up in land fills.
This article looks at 11 ways you can get rid of old clothes responsibly (spoiler alert: It doesn’t involve throwing it in the bin).
How to compost Tencel?
If you have a Tencel shirt or dress that is past its use-by-date and you’re thinking of what to do with it, how about decomposing it at home?
This is how you biodegrade your Tencel clothes in your backyard:
- The first step is to make sure that the garment in your hands is actually biodegradable. If it is one of the biodegradable Tencel blends listed above, it should be compostable.
- If it is blended with a non-biodegradable material, forget it. You will never succeed. These fabrics need industrial conditions and chemical processes to biodegrade. The process is so complicated and energy-consuming that it is almost not worth composting.
- Once you’re satisfied that you have a biodegradable piece of fabric, remove any accessories that won’t rot. This means buttons, hooks, tags and zippers.
- Then, shred the piece of cloth into thin strands. The smaller the pieces you end up with, the quicker it will biodegrade.
- Make sure your compost bin is in optimal conditions. In other words, fill it up with plenty of healthy, hungry worms.
- Bury the pieces of clothing deep in your compost bin and layer lots of other compostable organic matter on top.
No compost bin? Buy one or 
To wrap up
Pure Tencel is biodegradable. Unfortunately, many of our clothes are a blend of Tencel and other fibers. I’m not saying don’t buy anything but compostable clothes. That’s not practical at all. But when you buy a piece of clothing you know will be around a lot longer than you will be, make sure it’s something you really want that will last you years of wear.
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