Rieter

Neps

Index

Neps are small entanglements or knots of fibers. In general, two types of neps can be distinguished: fiber neps and seedcoat neps, that is, small knots that consist only of fibers and others containing foreign particles such as husk, seed or leaf fragments. Investigations made by Artzt and Schreiber  [11] indicate that fiber neps predominate, particularly fiber neps having a core mainly of immature and dead fibers. Thus it is clear that there is a relationship between maturity index  [3] and neppiness. Neppiness is also dependent, exponentially, on fiber fineness, because fine fibers have less longitudinal  The slenderness ratio (stiffness)stiffness than coarser fibers. The processing method also has a considerable influence. A large proportion of the neps in raw cotton is produced by picking and hard ginning, and the amount of neps is substantially increased in the blowroom. The card is the first machine to reduce the amount of neps to a usable level, and nep reduction at the card is achieved primarily by disentanglement rather than by elimination. Neps not only create disturbance in themselves as thick places, but also in dyed fabrics because they dye differently from the rest of the fibers, and thus become clearly visible in the finished cloth.

Based on the consolidated findings of Uster Technologies Inc. (Zellweger Luwa AG)  [28], the following scale represents the amount of neps per gram in 100% cotton bales:

  • up to 150 = very low;
  • 150-250 = low;
  • 250-350 = average;
  • 350-450 = high;
  • above 550 = very high.