New research could help dyeing sector
08/01/2009
Indigo is a vat dye and needs to be reduced to its water-soluble leuco-form before dyeing. This allows the actual dye to pass on to textile fibres. Glucose is known to be a good reducing agent, and Ms Vuorema's work demonstrates that it also works with indigo.
Glucose dyeing seems to suit plant-derived fibres, such as cotton and flax, which withstand a high pH (11-12). However, the research does not recommend its use for animal fibres, such as wool and silk, which can only withstand a pH of up to nine.
In her dissertation research, Ms Vuorema developed a new electrochemical method for determining the purity of indigo. She reduced plant-derived indigo using glucose and measured the indigo concentration in the mixture using a new method. The method can also be applied to assess the purity of other similar chemicals.
"The degree of purity of plant-derived indigo is fairly low. Crude indigo has a dye content of less than 50%, while synthetic indigo has a dye content of over 95%,” says Ms Vuorema. “The impurities and means to reduce them are not yet well known."
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