A. The Effect of Purified Dye and Crude Dye on the
Colour Produced and Dye Absorption on Textile Materials
The colour developed on dyed samples are determined by
using CIEL*a*b* system coordinates L*, a*, b*, C* and h*
values. L* value refers to the lightness of colours ranging
from zero for black, 50 for grey and 100 for white. The
positive and negative values of a* refer to red and green
colour components while the positive and negative values of
b* refer to yellow and blue colour components respectively.
The highest values of a* and b* for very brilliant colour are
approximately +80 or -80. For neutral point, the values of a*
and b* are zero.
The values of chroma C* and the angle of hue h* are used
to show the colour saturation and the range of colour, the
angle of hue, h*, being measured starting from red to yellow,
ie., hue angle 90 refers to yellow shade, hue angle 180 refers
to green shade, hue angle 270 refers to blue shade, etc. When
the value of chroma is increased, the colour will be more saturated.