Rayon is made from cellulose, the structural fiber found in plants, most commonly extracted from wood pulp. It starts as a natural material but undergoes heavy chemical processing to become a usable textile fiber, which is why it’s classified as a “semi-synthetic” or “regenerated” fiber rather than a purely natural or purely synthetic one. The result is a fabric that feels soft and silky but originates from trees.
The Raw Material: Wood Pulp and Other Plant Sources
Wood is the primary source of cellulose for rayon production. Most rayon wood pulp comes from softwood trees processed through an acid sulfite cooking method that strips everything away except the cellulose. Hardwoods like eucalyptus and beech can also be converted into rayon pulp using a different chemical process called the sulfate method.
Cotton is the other major cellulose source. Cotton cellulose produces a stronger rayon yarn than wood-derived versions, so manufacturers sometimes choose it when durability matters. In less common cases, cereal straws can serve as raw material. One specialty type of rayon called cupro skips wood entirely and uses cotton linters, the fine fuzz surrounding cotton seeds that’s left over from cottonseed oil production.
If you’ve seen “bamboo fabric” marketed as an eco-friendly textile, that product is almost always rayon made from bamboo pulp. The U.S. Federal Trade Commission requires these fabrics to be labeled as “rayon” or “rayon made from bamboo” because the bamboo plant is chemically dissolved and regenerated, not woven directly from bamboo fibers.
How Cellulose Becomes Fabric
Turning rigid wood pulp into a drapey fabric requires dissolving the cellulose completely, then reforming it into fine filaments. The most common method, called the viscose process, does this in several stages.
First, sheets of purified cellulose pulp are soaked in a strong sodium hydroxide (caustic soda) solution, about 18% concentration. This converts the cellulose into a reactive form called alkali cellulose. The treated material is then shredded into crumbs and left to age, which breaks down the cellulose chains to a more workable length.
Next comes the critical chemical step: the aged crumbs react with carbon disulfide gas at a controlled temperature of 20 to 30°C. This creates a compound called cellulose xanthate, which can dissolve in a dilute caustic solution to form a thick, honey-like liquid. That liquid is the “viscose” that gives the process its name.
After filtering and ripening, the viscose solution is forced through a spinneret, a nozzle with tiny holes between 0.05 and 0.1 mm in diameter, similar to a showerhead. The emerging filaments pass into an acid bath containing sulfuric acid, sodium sulfate, zinc sulfate, and glucose. The acid strips away the chemical modifications and regenerates almost pure cellulose, now in the form of continuous, fine threads that can be wound together into yarn.
Why It’s Called “Semi-Synthetic”
Rayon occupies an unusual middle ground in textiles. Its raw material is natural plant cellulose, the same basic substance found in cotton, linen, and hemp. But unlike those fibers, which are cleaned and spun more or less as they grow, rayon’s cellulose is chemically dissolved and rebuilt from scratch. The final fiber is nearly pure cellulose again, but it only exists because of intensive chemical processing. That combination of natural origin and manufactured structure is why textile scientists call it a regenerated or semi-synthetic fiber, distinguishing it from petroleum-based synthetics like polyester and nylon.
How Rayon Differs From Cotton
Because both rayon and cotton are cellulose fibers, they share a similar feel and breathability. But the regeneration process changes the internal structure of the cellulose, giving rayon distinct properties. Rayon absorbs roughly twice as much moisture as cotton. Under normal room conditions, rayon fiber holds about 11 to 13% moisture compared to cotton’s 8%. When fully soaked, rayon can swell and absorb nearly 70% of its weight in water.
That high absorbency comes with a tradeoff: rayon is weaker than cotton, especially when wet, and stretches more easily. This is why many rayon garments require gentle washing or dry cleaning.
Types of Rayon
Not all rayon is made the same way. The standard viscose process described above is the most widespread, but two major variants exist.
Modal uses the same basic viscose chemistry, with sodium hydroxide and carbon disulfide, but with modifications to the process that produce a stronger, more stable fiber. Modal is about 50% more absorbent per unit volume than cotton, making it popular for underwear, activewear, and bedsheets. It typically comes from beech wood pulp.
Lyocell (often sold under the brand name Tencel) takes a fundamentally different approach. Instead of carbon disulfide, it dissolves cellulose in a non-toxic solvent called NMMO. The key advantage is environmental: lyocell production uses a closed-loop system that recovers and reuses up to 99.7% of the solvent, dramatically reducing chemical waste. Standard viscose production, by contrast, releases carbon disulfide and other chemicals into air and water.
Cupro dissolves cotton linters in a solution of copper salts and ammonia, then regenerates the cellulose through a series of chemical baths. The resulting fiber is exceptionally fine and silky, often used as a lining fabric.
The Environmental Cost of Viscose
The viscose process is chemically intensive. Carbon disulfide, the key chemical that makes cellulose dissoluble, is toxic and volatile. The U.S. Environmental Protection Agency has studied carbon disulfide discharges from cellulose product manufacturers because of concerns about air and water contamination near production facilities. The open-system nature of traditional viscose manufacturing means significant quantities of chemicals escape rather than being captured and reused.
Sourcing also matters. When rayon pulp comes from old-growth or endangered forests rather than managed plantations, the environmental equation worsens. This is one reason the textile industry has increasingly pushed toward lyocell production, where the closed-loop solvent system and the ability to use sustainably farmed eucalyptus offer a cleaner alternative to the 19th-century viscose chemistry that still dominates global rayon output.