How rayon is made

Rayon is wood dissolved into a syrup, squirted through tiny holes into an acid bath, and turned back into fiber.

stations: 6
things upstream: 14
raw sources: 7
steps from the ground: 4

The short version

Rayon is regenerated cellulose. Wood pulp is soaked in caustic soda, pressed and shredded, then treated with carbon disulfide so it dissolves into a thick golden syrup called viscose. After ripening, the syrup is forced through the tiny holes of a spinneret into a sulfuric acid bath, where it hardens into filaments.

Soak the pulp in lye

Sheets of wood pulp, mostly pure cellulose, are soaked in strong caustic soda. The treated sheets are pressed between rollers to squeeze out the extra liquid.

Goes in
Wood pulp Caustic soda
Shred and age the crumb

The pressed sheets are shredded into a fluffy white crumb. The crumb sits for a time so the long cellulose chains shorten to the right length.
Turn it into xanthate

The white crumb is mixed in vats with carbon disulfide. This turns it into an orange-yellow crumb that can dissolve.
Dissolve and ripen

The crumb is dissolved in a caustic solution to form viscose, a thick, honey-like liquid. The liquid is left to ripen while its molecular weight changes, then filtered and degassed.

Goes in
Caustic soda
Squirt into an acid bath

Viscose is pumped through a spinneret, a plate with tiny holes, into a bath of sulfuric acid. The acid turns the liquid back into solid cellulose filaments in a moment.

Goes in
Sulfuric acid
Wash, desulfur and cut

The new filaments are washed to remove acid, treated to remove sulfur and bleached. They are then wound as continuous filament or cut into short staple lengths.

Goes in
Water

End of the lineRayon Next it goes into tampon.

Worth repeating

Charles Cross and his colleagues patented viscose in 1894 and named it for the highly viscous solution made along the way.
The first commercial viscose rayon was produced by Courtaulds in the UK in November 1905.
The Lyocell process makes the same kind of fiber without neurotoxic carbon disulfide, but costs more.