The high-molecular-weight gallotannic acid fraction of commercial tannic acid has been identified as the component preferentially absorbed by wool, and in comparison the gallic acid fraction has a rather lower affinity. Chlorination of the wool and an increase in temperature will substantially increase the rate of absorption. The effects of chemical modi fication of tannic acid and pH have also been studied.
The application of tannic acids to wool for the purpose of reducing its affinity for acid dyes requires a fixation with metal ions; aluminum salts have been found to be a practical and economical alternative to the traditional antimonyl or tin compounds.
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References
1.
Bird, C.L., "The Theory and Practice of Wool Dyeing," Society of Dyers and Colorists, Bradford, 1948, p. 137.
2.
King, H.G.C. and Pruden, G., Lower Limits of Molecular Weights of Compounds Excluded from Sephadex G-25 Eluted with Aqueous Acetone Mixtures. Application of the Results to the Separation of the Components of Tannic Acid, J. Chromatog.52, 285-290 (1970).
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Noble, E.I., Colored Effects on Wool by New Methods, Textile J. Australia20, 433-434 (1945).
