The mordant dyeing of wool using tannic acid and FeSO4, Part 1: Initial findings

Abstract C.I. Mordant Black 8 produced reddish-brown dyeings on wool of good light fastness, moderate rub fastness but poor fastness to washing at 40 °C. Subsequent afterchroming with Na2Cr2O7 provided deep, black dyeings of much improved fastness. The substitution of Na2Cr2O7 with FeSO4 also improved the fastness of the unmordanted dyeings but the ensuing brown shades displayed lower, all-round fastness to their afterchromed counterparts. When the dye was applied in combination with tannic acid, subsequent mordanting with ferrous sulfate yielded brown/greyish-brown dyeings of high colour strength and high all-round fastness. Of two methods that were used to produce such dye/tannic acid/FeSO4 ‘combination’ dyeings, namely, (dye + tannic acid)/FeSO4 and dye/(tannic acid + FeSO4), the latter yielded dyeings of superior fastness.