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.