Fiber cleanness: Impurities

Fiber cleanness: Impurities

In addition to usable fibers (lint), cotton stock contains foreign matter of various kinds [1,25]: 

Vegetable matter 

  • husk portions 
  • seed fragments 
  • stem fragments 
  • leaf fragments 
  • wood fragments 

Mineral material 

  • earth 
  • sand
  • ore dust picked up in transport 
  • dust picked up in transport 

Sticky contaminations 

  • honeydew (insect sugar) 
  • grease, oil, tar 
  • additives 

Other foreign matter 

  • metal fragments 
  • cloth fragments 
  • packing material (mostly polymer materials) 

Fiber fragments 

  • fiber particle (which finally make up the greater por- tion of the dust) 

 This foreign material can lead to extreme disturbances dur- ing processing. 

  Metal parts can cause fires or damage card clothing. Cloth fragments and packing material can lead to foreign fibers    in the yarn and thus to its unsuitability for the intended application. 


  Vegetable matter can lead to drafting disturbances, yarn breaks, filling-up of card clothing, contaminated yarn, etc. Mineral             matter can cause deposits, high wear rates in machines (grinding effects, especially apparent in rotor spinning), etc. 

   The new spinning processes are very sensitive to foreign matter. Foreign matter was always a problem but is becom- ing                 steadily more serious from year to year. This is due primarily to modern high-performance picking methods; hard ginning and       cleaning; pre-drying; careless handling during harvesting, packing, and transport; modern packing materials. 


   Today, foreign fibers, for example, have become almost a nightmare for the spinner. The amount of foreign material (primarily of           vegetable origin) is already taken into account in grading.


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   Fig. 10 shows the ranges for impurities in American cotton as given in the literature of the Trützschler company. The scale below           represents the degree of trash: 


  • up to 1.2% = very clean; 
  • 1.2-2.0% = clean;
  • 2.1-4.0% = medium; 
  • 4.1-7.0% = dirty; 
  • 7.1 % and more = very dirty. 


ITMF publishes biannually a survey on cotton contamina- tion and states most affected origins.