cotton

The word comes from the Arabic word qutn or qutun meaning cotton.  A long unicellular seed fibre grown on the outer skin of the cotton seed. Belongs to the mallow family as do hibiscus and okra. Vary from 10mm to 55mm in length, wild varieties, gossypium thurberi, are brown in colour and cultivated hybrid types, from which they derive, are white.

The length of cotton fibre, known as staple length, is classified in three main groups:

• Fine, over 30mm long staple, high lustre fibre

Best quality cotton: Sea Island (39mm and over in staple length, grown in the West Indies, Central America and Mexico), Egyptian, Sudanese, Peruvian, American Pima and East African (between 30mm to 38mm)

• Medium, between 26mm to 29mm long staple American Upland (the bulk of production in the United States of America)
• Short, below 26mm long staple, coarse fibre India and China

Before cotton is spun into yarn the fibre is put through a series of pre-spinning processes:

Picking
Bales of cotton are sent from the ginnery (the gin) and arrive at the spinning mill and are first put through the bale-breaker and then onto the opener. The opener literally opens the compressed cotton fibre ready for the following rigorous processes. The cotton, having then been cleaned in the picker (or scutcher) and all the seeds and heavy impurities are extracted, enters the lap former which produces a continuous roll, 50mm thick x 1000mm wide, of semi-cleaned cotton fibre, called a lap.

Carding
The lap is passed through a set of revolving cards which disentangles and begins to align the fibres. As the carded cotton comes off the card (carding machine) a thin web, about 10mm thick, is produced and is rolled into loose rope of fibre called a sliver.

Combing
The finest quality cotton yarns are spun with combed cotton, therefore the importance of this process is to eliminate all short fibres and parallel all the remaining long fibres. The short fibres, called noils, are usually blended with shorter cottons and spun into cheaper, carded yarns. The combing process produces a continuous rope (20mm diameter) of clean straight cotton fibre called a sliver.

Drawing
Several slivers are combined and blended through the draw frame, eliminating any further irregularities, to form a single sliver.  By combining the slivers to make one sliver, in this process, it ensures that any variations in the ultimate yarn are eliminated.

Roving
The sliver is drawn out still further into a finer strand about the 8mm thick and a slight twist put into it to form the roving.

Spinning
The roving is now drawn out still further and twisted to produce a single yarn.  It is at this stage that the speed of the roving entering the rollers of the spinning machine is strictly controlled to produce a specific size (count) of yarn.  The singles yarn can then be doubled on a doubler to produce a two-fold yarn.