A Pre-treatment Process for Natural Dyeing of Wool to Impar t Durable Antimicrobial Efficacy

  • Raja, A.S.M. (Division of Textile Manufacture and Textile Chemistry, Central Sheep and Wool Research Institute) ;
  • Thilagavathi, G. (Department of Textile Technology, PSG College of Technology)
  • Received : 2011.04.29
  • Accepted : 2011.06.07
  • Published : 2011.06.27


A pre-treatment process has been developed for natural dyeing of wool by which the dyed materials have been imparted antimicrobial efficacy against both gram-positive and gram-negative bacteria durable up to 20 washes. In this process, wool fabrics were treated with citric acid under oxidizing condition prior to dyeing. The treated fabrics were then dyed with four different types of natural dye powders obtained from leaves of silver oak, wattle, tanner's senna and flame of forest. All the natural dyes produced yellowish brown colour on wool fabrics. The washing and light fastness properties of the fabrics subjected to pre-treatment were one grade higher compared to those of the dyed fabrics without pre-treatment. The pre-treated wool fabrics showed antimicrobial efficacy against both gram-positive bacteria (Staphylococcus aureus) and gram-negative bacteria (Escherichia coli). The fabrics dyed without pre-treatment showed antimicrobial efficacy against gram-positive bacteria (Staphylococcus aureus) only. The durability of antimicrobial efficacy was higher in pre-treated and dyed wool fabrics compared to the dyed fabrics without pre-treatment.


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