How Variety of Color is Secured
The color which is fixed on the fabric as a result of chemical action between mordant and dye is frequently very different from that of the dye itself. Logwood dye when used alone produces a reddish brown color of no value either for beauty or permanence; but if the fabric to be dyed is first mordanted with a solution of alum and oxalic acid and is then immersed in a logwood bath, it acquires a beautiful blue color.
Moreover, since the color acquired depends upon the mordant as well as upon the dye, it is often possible to obtain a wide range of colors by varying the mordant used, the dye remaining the same. For example, with alum and oxalic acid as a mordant and logwood as a dye, blue is obtained; but with a mordant of ferric sulphate and a dye of logwood, blacks and grays result. Fabrics immersed directly in alizarin acquire a reddish yellow tint; when, however, they are mordanted with certain aluminium compounds they acquire a brilliant Turkey red, when mordanted with chromium compounds, a maroon, and when mordanted with iron compounds, the various shades of purple, lilac, and violet result.