Wood viscose

Viscose made from wood is categorized as a “manufactured” or “man-made” fibre created from cellulose found in trees. It is typically derived from spruce or pine (although any plants or trees can be used to make viscose) and is then chemically processed and regenerated to form a new polymer using the viscose process. Although viscose is generally not considered a sustainable fibre due to its highly chemical process, new forms of viscose-type materials are emerging—such as lyocell—that have the same material characteristic, but are produced by non-toxic processes and operate in a closed loop system where outputs are recovered, filtered and reused.[1]

Viscose is the oldest manufactured fibre. The viscose process was developed in the late 1800s as an inexpensive alternative to silk. Viscose has a silk-like aesthetic, drapes well, is easy to dye, and is highly absorbent. It is a good conductor of heat, so it is a cool, comfortable fibre good for use in warm weather. Viscose is also relatively inexpensive compared to other fibres, and blends well with many fibres—sometimes used to reduce cost, or contribute lustre, softness, absorbency or comfort.[1]

Cultivation

Wood feedstock may be sourced from ancient and endangered forest.[2]

Processing

To transform hardwood-derived materials into silky fabric, the cellulose must be separated from other compounds found in trees. Sodium hydroxide (caustic soda) and sodium sulfide are commonly used to remove the lignin that binds the wood fibres together, and in some cases bleach is required to whiten the pulp. In a complex process the pulp is steeped in caustic soda to produce alkali cellulose, which is then aged or oxidized before reacting with carbon disulfide to create sodium cellulose xanthate. This xanthate is dissolved in caustic soda to form a syrup-like spinning solution or “viscose,” which can then be extruded through a spinneret to form viscose fibres.[3]

The viscose manufacturing process is chemically intensive and requires copious amounts of water. Wastewater effluents from processing must be properly treated to avoid contamination of surrounding water bodies. Air emissions caused by the viscose process include sulfur, nitrous oxides, carbon disulfide and hydrogen disulfide. Chronic exposure to carbon disulfide can cause damage to the nervous system in humans.[3]

Dyeing and printing

The dyeing processes for viscose is a multi-step process that involves ample amounts of water at high temperatures (50°-95°C), salt, acetic acid and caustic soda. Mild peroxide bleach may also be necessary to remove residues of sulfur.

Consumer care/washing

Viscose is typically dry-clean only, due to delicacy of the fabric when wet. Some types of viscose can be machine or handwashed. Electricity and water use in the care of the garment can cause significant environmental impacts. Certain chemicals used in dry-cleaning and at-home products have been reported to have detrimental effects on humans and the environment, and contribute to ozone depletion and can pollute wastewater.

End of use

According to the Federal Trade Commission (FTC) in the United States, viscose products are non-biodegradable because they will not break down in the required time under customary disposal conditions.[7] Viscose is typically used in fast-fashion garments that are worn and quickly discarded. If these garments end up in landfill, they are likely to remain there for decades.

• Discourage suppliers from using old-growth trees as feedstock for viscose fabrics, especially those harvested from the following endangered forest areas: Canadian boreal forest; coastal temperate Rainforests of the Pacific Northwest; US; Chile; Tropical forests of Indonesia; and the Amazon.[2]

• Encourage suppliers to use raw materials sourced from responsibly managed forests registered in the Forest Stewardship Council (FSC) certification system and/or sourced from Programme for the Endorsement of Forest Certification schemes (PEFC) and Forest Stewardship Council (FSC) certified forests.[2]

Lenzing Viscose®

Lenzing Viscose® gives more attention to overall sustainability. The various chemical and waste products that result from the production process are recycled or sold. Viscose from Lenzing is PEFC certified, which means that the raw material is sourced from responsibly managed forests. Lenzing Viscose® and Lenzing Modal® Austria are the only man-made fibres which are carbon neutral.

Lyocell

New forms of viscose-type materials are emerging, and can be made through various types of processes, including lyocell. Lyocell material properties are similar to traditional viscose and fibre production is also similar to that of generic viscose in that hardwood material is dissolved through an intensive chemical process into a pulp, which is then extruded to form fibres. However, for lyocell, the solvent used to transform the pulp into fibre is amine oxide (NMMO=N-Methyl-Morpholine-N-Oxide), which is considered non-toxic. The lyocell fibre manufacturing process also operates as a closed loop system, in which 99% of the solvent is recovered, filtered and reused. Any remaining emissions are broken down harmlessly in biological wastewater treatment plants.[9]

OEKO-TEX certified viscose

OEKO-TEX is an independent, third party certifier that offers two certifications for textiles: OEKO-TEX 100 (for products) and OEKO-TEX 1000 (for production sites/factories). OEKO-TEX 100 label aims to ensure that products pose no risk to health. OEKO-TEX certified products do not contain allergenic dye-stuffs and dye-stuffs that form carcinogenic aryl-amines. The certification process includes thorough testing for a long list of chemicals. Specifically banned are: AZO dyes, carcinogenic and allergy-inducing dyes, pesticides, chlorinated phenols, extractable heavy metals, emissions of volatile components, and more.[10]

There are a few suppliers in China that are currently offering viscose from PEFC and FSC certified forests. Expressing interest in PEFC and FSC certification can influence the supplier’s raw material sourcing strategy and lead to greater availability of responsibly sourced feedstock for viscose fabric. OEKO-TEK® Standard 100 certified viscose is available. Manufacturers can be found at: https://www.oeko-tex.com

Viscose and lyocell can be used in a variety of textile woven and knitted applications. Depending on the weight and construction of the cloth, these fabrics may be suitable for shirts, skirts, dresses, evening gowns, home furnishings and bedding.

lyocell process If processed with a lyocell process.
PEFC-certified Must be verified, and can be claimed on POS items at retail.
FSC-certified Must be verified, and can be claimed on POS items at retail.
Lenzing Viscose® If verified and used.
OEKO-TEK® Standard 100 certified If verified and used.

1. Shift to existing environmentally beneficial fabrics when possible. These fabrics include fabric derived from organic cotton, recycled fabrics, hemp, flax, and dissolving pulp from bamboo and eucalyptus plantations that are PEFC or FSC-certified.

2. Use wood pulp from PEFC and FSC-certified plantations, and produce the fabric with lyocell process. Communicate the difference between the viscose and lyocell processes to consumers on your website and hangtags.

3. Encouraging handwashing on the hangtag and labeling/POS would influence the consumer to take an active role in reducing environmental impacts of viscose at the consumer washing stage.

1. https://www.swicofil.com/products/200viscose.html
2. https://www.canopy.org/index.php
3. oecotextiles.wordpress.com/2009/08/19/348/
4. https://www.eksoy.com/PDF/VISCOSE%20AND%20BAMBOO.pdf
5. textilefashionstudy.com/process-flow-chart-of-viscose-fabric-dyeing/
6. textilelearner.blogspot.com/2012/09/100-viscose-fabric-dyeing-method-dyeing.html
7. ftc.gov/opa/2009/08/bamboo.shtm
8. lenzinginnovation.lenzing.com/fileadmin/template/pdf/Texworld_USA_2012/16_01_2012_2_PM_Lenzing_Edelweiss.pdf
9. https://www.lenzing.com/sites/botanicprinciples/website/index.htm
10. https://www.OEKO-TEK.com/media/downloads/Factsheet_OETS_100_EN.pdf