The cotton is a cellulose fibre. The molecules of cellulose is the main substance (97%), and pectin, protein, fats are the other substances present with very less proportion in the cotton fibre. Cotton is chemically resistance. It also withstands the action of water and light for a longer time. Cotton may easily ignite so fire safety rules must be strictly observed.
The properties and structure of cotton fibres are greatly dependent on the degree of maturity of separated fibres. Cotton fibre has the shape of a tube cross-section. The unripe fibre has the shape of thin walled pipe. Unripe fibres are weak and exhibits poor dyeability. The presence of such fibres impairs cotton quality. When the degree of maturity is higher, the pipe has thicker walls, and so fibres become stronger and more flexible. They also become crimpier.