Steps in the production process:[1]
1) Cellulose is purified from wood pulp or cotton linters.
2) This cellulose is mixed with glacial acetic acid, acetic anhydride, and a catalyst (sulfuric acid).
3) The mix is allowed to age for 20 hours, when partial hydrolysis occurs (and sulfate groups are removed).
4) Cellulose acetate is precipitated as acid-resin flakes.
5) The flakes are dissolved in acetone (a volatile solvent).
6) The solution is filtered.
7) The spinning solution extruded in the form of filaments in a column of warm air. The solvent evaporates and is recovered.
8) The filaments are stretched and wound onto beams, cones, or bobbins ready for use.