Cotton in Brief
|A Short Look Back at the
History of Cotton |
Cotton textiles have clothed people for
many thousands of years. This is proven by the remains of cotton capsules and
textiles discovered in a cave near Tehuacán in Mexico and dated at the
time of 5,800 BC. In the old world the oldest finds (around 3,000 BC) of cotton
textiles and twine come from the region that is now Pakistan. The first
cultivated cotton fields are thought to have been in the Indus delta.
- Biological Data
belongs to the mallow family. The cotton fibre is the seed fibre of the
gossypium plant. Its blossom is very similar to that of the domestic hollyhock
and hibiscus. After blossoming, the ovary in the chalice is transformed into an
egg-shaped capsule that springs open and allows the seed fibres to ooze out. A
cotton capsule contains around 30 seeds and on each seed there are 2,000 to
7,000 seed fibres. Depending on the type, climate and cultivation methods, the
cotton plant can reach a height of 25 cm to more than 2 m. It is mostly grown as
a bush-high annual plant. Cotton is grown on perennial plants in only a few
areas (Peru and Northern Brazil).
The time between planting and
ripening varies between 175 and 225 days. The plants need humidity at planting
and a lot of warmth in the ripening stage. The harvested cotton is stored for
around 30 days to mature and dry and is then brought to the de-seeding plants
(gins), where the fibres are separated from the kernels. About 35kg of fibre is
obtained from 100 kg of cotton seed.
Raw cotton is traded according to colour, purity, fibre length, (staple),
fineness, strength and uniformity. Some types are hard and rough to the touch
while others are silky soft. In terms of colour, raw cotton is categorised as
white, creamy, lightly spotted, spotted. There are also types which appear
yellow-brown, as well as coloured growths in shades of green and brown.
An important quality characteristic is the staple length.
Interestingly, the finest and longest cotton fibres have the highest strength
relative to their cross-section - a characteristic that is very valuable in the
spinning of the finest cotton yarns.
Cotton fibre can be stretched by
around 8 -10% both in both a wet state and dry state. Its wet strength is
greater than its dry strength.