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    Generic Name Colour Index
    Blue FFC Blue 71
    T.Blue BL Blue 199
    T.Blue G Blue 86
    Black NA Black 22
    Black VG Black 19
    Black OB Black 80
    Brown MR Brown 2
    Scarlet 4BS Red 23
    Properties of  DIRECT DYES :
    Direct dyes are usually applied with the addition of electrolyte at or near the boil in the machines capable of running at atmospheric pressure .But in HTHP dyeing machines it is carried out at temperatures above the boil in case of pure as well as blended yarns.
    An addition of alkali, usually sodium carbonate, may be made with acid-sensitive direct dyes and with hard water as well as to enhance the dye solubilisation. When cellulose is immersed in a solution of a direct dye it absorbs dye from the solution until equilibrium is attained, and at this stage most of the dye is taken up by the fibre. The rate of absorption and equilibrium exhaustion vary from dye to dye. The substantivity of the dye for cellulose is the proportion of the dye absorbed by the fibre compared with that remaining in the dyebath.
    Types of  DIRECT DYES :
    (1) Class A – dyes that are self-levelling, i.e. dyes of good migration or leveling properties.
    (2) Class B – dyes that are not self-levelling, but which can be controlled by addition of salt to give level results; they are described as salt-controllable.
    (3) Class C – dyes that are not self-levelling and which are highly sensitive to salt, the exhaustion of these dyes cannot adequately be controlled by addition of salt alone and they require additional control by temperature; they are described as temperature-controllable.
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