Grading system of cotton


 The cotton qualities from place to place and plant to plant differ the difference in quality can be expressed in grading and staple length. Grade is generally determined from three factors i.e,

(a) Colour,
(b) Trash content and
(c) Ginning quality



Best cotton is only white in colour. But continued exposure to weathering and micro-organisms cause white cotton to lose its brightness. The colour groups present in cotton are White,
 Light spotted (Lt Sp), Spotted (Sp), Tinged (Tg), Yellow stained (YS), Light grey (Lt Gy), and Grey (Gy).

Trash Content:

The trash includes such materials 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 Strict Good Middling (SGM), Good Middling (GM), Strict Middling (SM), Middling (M), Strict low middling (SLM), Low middling (LM), Strict good ordinary (SGO) and Good ordinary (GO).Sometimes, depending upon the trash content, plus (+) can be given to any grade like SLM+ or SGM+.

Quality of Ginning:

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.

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