Dyeing of fabrics with natural dyes often leads to problems such as narrow range of shades, and low colour fastness of dyed textiles. Attempts to overcome these problems have been mainly focused on the use of mordants. In addition to creating affinity between dye and fibre, the use of mordants also change the hue of certain dyes. Different mordants used with same dye may darken, brighten or drastically alter the final colour of the dyed fibre.
Mordant dyes form the largest class of natural organic dyestuff. Those dyes which have higher affinity for mordanted fibres are called mordant dyes. This classical definition of mordant dyes has been extended to cover all those dyes which form a complex with metal mordant. The complex may be formed by first applying the mordant (pre-mordanting) or by simultaneous application of the mordant and the dye (simultaneous mordanting) or by after treatment of the dyed material with mordant (post-mordanting).
Here is a list of some metallic and biomordants used in natural textile dyeing:
List of metallic mordants used in natural textile dyeing
|Conventional metallic mordants
|Newly discovered metallic mordants|
List of plants used as source of biomordants in natural textile dyeing
|Eucalyptus spp.||Used as sources of tannin mordant|
|Symplococcus spp.||Al-hyperaccumulating plants used as substitute of alum mordant|
|Pyrus pashia||Cu rich plant used as substitute of copper mordant|
Source: M. Shahid, Shahid-ul-Islam, F. Mohammad, Recent advancements in natural dye applications: A review, J. Clean. Prod., 53 (2013) 310-331. http://www.sciencedirect.com/science/article/pii/S0959652613001698