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Updated: June 18, 2025
But the case with regard to textiles made from vegetables fibers is quite different; upon materials made from cotton, flax, jute, or other fiber of the vegetable kingdom, the new aniline colors cannot be fixed without the assistance of other bodies acting the part of mordants.
The lime used neutralises acids in the contaminated and impure water, precipitates colouring matters, mordants, soap, albuminous matters, etc. Tests of Purity. I will now describe a few tests that may be of value to you in deciding as to what substances are contaminating any impure waters that may be at hand. Iron.
The material used, also, is even more impervious and resisting to the action of aqueous solutions of dyes and mordants than the raw wool would be. In short, it is impossible to mordant and to dye shellac by any process that will dye wool.
Why, when she learns the doctrine of mordants, the substances by which different colors are set, should she not learn it with some practical view to future life, so that she may know how to set the color of a fading calico or restore the color of a spotted one?
I think we have now got a clue to the principle of mordants and also to the importance of a sound chemical knowledge in dealing most effectively with them, and I may tell you that the man who did most to elucidate the theory of mordanting is not a practical man in the general sense of the term, but a man of the highest scientific attainments and standing, namely, Professor Liechti, who, with his colleague Professor Suida, did probably more than any other man to clear up much that heretofore was cloudy in this region.
This dye works best in a neutral bath, but it will do what not many dyes will, namely, dye in either a slightly alkaline or slightly acid bath as well. Orchil is not applicable in cotton dyeing. Being a substantive colour no mordants are needed in dyeing silk and wool with it. The colour produced on wool and silk is a bright magenta-red with bluish shade.
Thus it will be observed, that the art of dyeing permanent colours depends on this intermediate principle, which is termed a mordant. These mordants are very numerous; and on a knowledge of them appears to rest the principal secret of dyeing.
Then of wood colours we have further: quercitron, Persian berries, fustic and the tannins or tannic acids, comprising extracts, barks, fruits, and gallnuts, with also leaves and twigs, as with sumac. All these colours dye only with mordants, mostly forming with certain metallic oxides or basic salts, brightly-coloured compounds on the tissues to which they are applied.
In some cases the lime soaps act like mordants, attracting colouring matter unequally, and producing patchy effects. In the dye-baths in which catechu and tannin are used, there is a waste of these matters, for insoluble compounds are formed with the lime, and the catechu and tannin are, to a certain extent, precipitated and lost.
The method usually employed to mordant woollen fabrics consists in boiling them with weak solutions of the metallic salts used as mordants, often with the addition of acid salts, cream of tartar, and the like.
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