Rayon is a fiber made from natural cellulose (plant material) that has been chemically dissolved and reformed into threads. It sits in an unusual category: neither fully natural like cotton nor fully synthetic like polyester. The raw material comes from plants, but it takes heavy chemical processing to turn wood pulp into soft, silky fabric. This makes rayon what the textile industry calls a “regenerated” fiber, and it accounts for about 8.4 million tonnes of global production annually.
What Rayon Is Made From
Rayon starts as cellulose, the structural material in plant cell walls. Wood pulp is the primary source today, though cotton fibers and even cereal straws can be used. Since 1937, U.S. federal law has defined rayon as any textile fiber produced chemically from cellulose or a cellulose compound. The key distinction from cotton is that while cotton fibers are used more or less as they grow on the plant, rayon requires dissolving that cellulose into a liquid solution and then rebuilding it into new fibers with a different internal structure.
This rebuilt structure is what gives rayon its distinctive feel. The fibers come out smoother and more uniform than raw cotton, which is why rayon often has a silky drape that natural plant fibers can’t match on their own.
How Viscose Rayon Is Produced
The most common type of rayon is viscose, and its production is a multi-step chemical process. Wood pulp or cotton fibers are first soaked in a strong sodium hydroxide solution to break down the cellulose into a reactive form called alkali cellulose. This material is then treated with carbon disulfide at controlled temperatures (20 to 30°C) to create a compound called cellulose xanthate, which dissolves into a thick, honey-like liquid.
That liquid is forced through a device called a spinneret, essentially a showerhead with tiny holes, into an acid bath. The bath contains sulfuric acid to solidify the cellulose back into fiber form, sodium sulfate to speed up coagulation, and zinc sulfate to cross-link the cellulose molecules and give the fibers strength. What emerges are long, continuous filaments that can be cut to any length and spun into yarn.
Types of Rayon
Not all rayon is the same. The manufacturing process can be tweaked to produce fibers with significantly different properties, and three main types dominate the market.
Viscose rayon is the original and most widely produced version. It uses carbon disulfide and sulfuric acid in production, making it the most chemically intensive. The resulting fiber is soft and breathable but loses significant strength when wet.
Modal is a modified version of viscose with an adjusted spinning process. Manufacturers increase the zinc sulfate concentration in the precipitation bath and alter the spinning solution to produce fibers with a tighter internal structure. Modal is about 50% more absorbent per unit volume than cotton, which makes it popular for underwear, activewear, and bed sheets.
Lyocell (often sold under the brand name Tencel) represents a fundamentally different approach. Instead of using carbon disulfide and sodium hydroxide, lyocell dissolves cellulose pulp directly in a non-toxic organic solvent. The process doesn’t involve a chemical transformation of the cellulose, just dissolution and reformation. The solvent is recovered at a rate of 99.8%, making it far cleaner than viscose production. Lyocell fibers tend to be stronger, especially when wet.
A less common fourth type, cuprammonium rayon (sometimes called cupro or Bemberg silk), dissolves cellulose in a solution of copper salts and ammonia. It produces exceptionally fine fibers and is primarily used for linings in high-end garments.
How Rayon Feels and Performs
Rayon absorbs roughly twice as much moisture as cotton. Under normal conditions, the fiber holds about 11 to 13% moisture content, compared to cotton’s 8%. When fully soaked, rayon can absorb nearly 70% of its weight in water. This makes rayon feel cool against the skin and comfortable in hot, humid weather.
The trade-off is structural. Rayon’s rebuilt cellulose arrangement makes it weaker and more stretchy than cotton, and this weakness gets worse when the fibers are wet. Water causes the fibers to swell, which is why rayon garments are prone to shrinking and losing their shape after washing. This swelling shrinkage is a direct result of how aggressively the fibers absorb moisture.
Rayon drapes beautifully, which is why it shows up in flowy dresses, blouses, and curtains. It also blends well with other fibers. Pairing rayon with polyester, for example, combines rayon’s moisture-wicking comfort with polyester’s durability and shape retention.
Environmental Concerns
The biggest environmental issue with conventional viscose rayon is carbon disulfide. This chemical is toxic to aquatic life at low concentrations: freshwater organisms experience chronic harm at just 1 milligram per liter and acute toxicity at 3 milligrams per liter. A 2011 EPA study found that 47% of sampled discharge concentrations from U.S. cellulose product manufacturers exceeded the chronic toxicity threshold, and 28% exceeded the acute level.
At the time of that study, no federal regulation set specific limits on carbon disulfide discharges from these facilities. Permit writers relied on state water quality standards and best professional judgment to set limits on a case-by-case basis.
Modern plants use air pollution controls that can capture up to 99% of carbon disulfide emissions through condenser systems, though simpler methods like biofilters capture only about 80% and wet scrubbers around 65%. The variation is significant: a plant’s environmental footprint depends heavily on which technologies it uses and whether it operates a closed-loop system that recycles water and chemicals.
Lyocell sidesteps these problems almost entirely. Its non-toxic solvent and near-complete chemical recovery rate make it the cleanest option in the rayon family. For lyocell production, the main environmental concerns shift to energy use and the sustainability of the wood pulp supply rather than chemical pollution.
Caring for Rayon Fabric
Rayon’s sensitivity to water is the single most important thing to know about caring for it. When rayon fibers absorb moisture, they swell and weaken, which means aggressive washing and wringing can permanently distort the fabric. Many rayon garments carry “dry clean only” labels for this reason.
If you do wash rayon at home, cold water and a gentle cycle minimize damage. Lay the garment flat to dry rather than hanging it, since the weight of waterlogged rayon can stretch it out of shape. Iron on a low setting while the fabric is still slightly damp, and use a pressing cloth to avoid scorching the surface. Modal and lyocell are more forgiving with water than standard viscose, so check the fiber content on your garment’s label to gauge how cautious you need to be.