What is modal fabric? What it is made of, and is it natural
Not plasticNot natural either: chemically regenerated
Fiber Facts
Modal
- Type
- Regenerated cellulose (made from plants, chemically processed)
- Made from
- Wood pulp, often beech, regenerated through the viscose process
- Fiber family
- Rayon (regenerated cellulose)
- ISO definition
- Cellulose fibre with high breaking strength and high wet modulus
- Process
- Viscose process, using carbon disulfide
- Share of man-made cellulosic fiber (2024)
- About 3%
Every figure is sourced at the foot of the page.
What modal is made of
Modal is made from wood cellulose. Lenzing, the Austrian company behind the TENCEL Modal brand, makes its modal mainly from beech wood sourced in Austria and neighboring countries. Other producers use other pulps, so “modal” on a label does not tell you which tree it came from.
The international fiber standard ISO 2076 defines modal as a cellulose fiber with a high breaking strength and a high wet modulus: it stays strong and holds its shape when wet, where ordinary viscose weakens.
How modal is made
Modal is made by the viscose process. Wood pulp is soaked in sodium hydroxide, reacted with carbon disulfide, dissolved, and spun into a sulfuric acid bath where it sets into filaments. The process is adjusted to give a stronger fiber; the European Commission describes modal as viscose with improved characteristics.
Is modal natural or plastic?
Neither. Modal is regenerated cellulose. US law defines rayon, the family modal belongs to, as a manufactured fiber of regenerated cellulose, and the FTC permits modal as a name on US labels. It is not a synthetic polymer, so it is not plastic, and regenerated cellulose fibers fully biodegraded in seawater within about 35 days in lab tests.
Modal, polyester and cotton
| Polyester | Modal | Cotton | |
|---|---|---|---|
| What it is | Plastic (PET), mostly from fossil fuels | Wood cellulose, dissolved and respun | Seed fiber, grown and spun |
| Process chemical of concern | Antimony catalyst, left in the fiber | Carbon disulfide, in the factory | No polymer or dissolving step |
| Is it plastic? | Yes | No | No |
| Fibers in seawater | Did not degrade in 428 days | Regenerated cellulose: about 35 days | Natural cellulose: about 35 days |
| Share of world fiber, 2024 | 59% | About 3% of cellulosics | 19% |
Modal in underwear and loungewear
Modal is used for underwear, T-shirts and pajamas, and it is often blended with elastane (spandex) or polyester for stretch. Those are synthetic polymers. A modal garment is plastic-free only if the fiber content line shows no polyester, elastane, spandex or nylon.
Frequently asked questions
Is modal a natural fiber?
No. Modal is made from wood, but the cellulose is dissolved and spun into new fiber, so it is a manufactured fiber of the rayon family. Natural fibers such as cotton and linen are grown as fiber.
Is modal plastic?
No. Modal is regenerated cellulose, not a synthetic polymer. Modal garments are often blended with elastane or polyester, which are plastic, so check the full fiber content.
What is the difference between modal and viscose?
Modal is made by the viscose process but engineered for higher strength, especially when wet. Both are rayon. Viscose is 80% of man-made cellulosic fiber; modal is about 3%.
Is modal 100% cotton?
No. Modal is rayon made from wood pulp, not cotton. A label must name each fiber and its percentage, so a modal-cotton blend lists both.
Is modal better than cotton?
Both are cellulose and neither is plastic. Cotton is grown as fiber and spun; modal is wood dissolved with carbon disulfide and respun. Cotton skips the chemical step.
Sources
- International Organization for Standardization (2010), ISO 2076:2010 Textiles — Man-made fibres — Generic names. iso.org
- European Commission, Joint Research Centre (2007), Reference Document on Best Available Techniques in the Production of Polymers, Chapter 11: Viscose fibres. bureau-industrial-transformation.jrc.ec.europa.eu
- US Federal Trade Commission, Textile Fiber Products Identification Act rules, 16 CFR §303.7, Generic names and definitions for manufactured fibers. ecfr.gov
- US Federal Trade Commission, Threading Your Way Through the Labeling Requirements Under the Textile and Wool Acts. ftc.gov
- European Commission (2021), Commission guidelines on single-use plastic products in accordance with Directive (EU) 2019/904, OJ C 216, 7.6.2021. eur-lex.europa.eu
- Textile Exchange (2025), Materials Market Report 2025. textileexchange.org
- Lenzing AG (2021), Annual Report 2021: Product portfolio. reports.lenzing.com
- Lenzing AG (2024), TENCEL Modal fiber claim-proof snapshot. tencel.com
- Agency for Toxic Substances and Disease Registry (2025), Toxicological Profile for Carbon Disulfide. atsdr.cdc.gov
- Royer SJ, Greco F, Kogler M, Deheyn DD (2023), Not so biodegradable: Polylactic acid and cellulose/plastic blend textiles lack fast biodegradation in marine waters, PLOS ONE 18(5):e0284681. doi.org