Fabric Preparation processes for dyeing and printing

  • Created by: Emmy sale
  • Created on: 15-05-15 11:44
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  • Fabric Preparation for dyeing and printing- processes!
    • Grey or Loomstate cloth is a natural creamy colour fabric, which has just come from the loom or knitting machine but it is not ready to be dyed or used straight away.
      • Fibres -especially natural fibres- have impurities in them like fats, waxes and salts. These have to be removed before the fabric can be dyed or finished as the colour or finish will not attach itself evenly to the fabric.
    • SCOURING: this removes fatty and waxy impurities that would prevent fabric from being 'wetted'.Cotton method are scoured by boiled them in caustic soda solution. This method would not be appropriate for wool fabrics as they would be damaged by the heat and the alkali- instead they are moved through warm detergent solutions to remove the fatty deposits in the fibres. More modern methods involve 'washing' the fabrics in solvents to remove the oils and greases.
    • HEAT SETTING: can be used to set fabrics with a thermoplastic fibre content to their correct width.
    • DESIZING: size= a starch, gum or gelatine type of substance which is applied to warp yarns before they are woven into fabrics. This helps to strengthen them so that they will be more able to stand up to constant movements of the loom. Most of these substances are soluble in water so they can be removed easily by washing with enzymes
    • BLEACHING: fabrics are sometimes bleached to obtain a fabric which is evenly white before colour added. Cotton fabrics= bleached using carefully controlled amounts of hypochlorite bleach or hydrogen peroxide. Both of these are oxidising bleach, so they can remove unwanted colour by adding oxygen to the stain to make it colourless.
    • WOOL: is often left in its naturally creamy colour. It is never treated with chlorine bleaches, as these will damage the scales on the wool fibres. It can be bleached using hydrogen peroxide or using sulphur dioxide gas, a reducing agent which works by removing oxygen from the stain to leave it colourless.
    • STENTERING: is a process used to pull woven fabrics back to their correct width after they have passed through other processes
    • Singeing: to remove fine hairs from the surface of fabric


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