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Natural FibresTextile Fibres

Grading of Cotton Fibres

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Grading of Cotton Fibres

The quality of cotton fibre differ from place to place and plant to plant. The difference in quality can be expressed in grading and staple length. Grade is generally determined from three factors viz. (a) colour, (b) trash content and (c) ginning quality.

 

Colour

Best cotton is generally white in colour. White cotton loses its brightness and it becomes yellowish in nature Because of continued exposure to weathering and the action of microorganisms. Following are the colour groups which are present in cotton fibre:

White

 

 

Light Spotted

:

Lt Sp

Spotted

:

Sp

Tinged

:

Tg

Yellow Stained

:

YS

Light Grey

:

Lt Gy

Grey

:

Gy

 

Trash Content

Trash is the impurities which are present there in the cottonfibres. The trash includes materials such as leaf, stems, hulls, bark, seeds, shale, motes, grass, sand, oil and dust. Cottons which contain minimum amount of trash after ginning have highest spinning value. Depending upon the trash content, cotton can be graded as follows:

Strict Good Middling

:

DGM

Good Middling

:

GM

Strict Middling

:

SM

Middling

:

M

Strict Low middling

:

SLM

Low middling

:

LM

Strict good Ordinary

:

SGO

Good ordinary

:

GO

 

Sometimes, depending upon the trash content, plus (+) can be given to any grade like SLM+ or SGM+.

Quality of Ginning

In ginning process, we separate the cottonfibres from seed.  During this process there is a chance of formation of entanglements of fibres (neps). Neps are adversely affecting yarn and fabric appearance as well as quality. Presence of neps and naps are two important factors to determine the quality of cotton. Neps are small tangled knots of fibre that are visible as dots. This type of cotton is known as neppy cotton. Naps are large clumps or matted masses. of fibres that contribute to the rough appearance. This type of cotton is known as nappy cotton. The quality of ginning is considered as better if it produces zero or minimum number of neps.

 

In general, the grading indicates the trash and colour of the cottonlike LM Tg, M Lt Gy etc.

 

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