Dyeing & Bleaching Paper 2, May/June 2014  
Questions: 1 2 3 4   Main
General Comments

Question 6



(a)        What is bleaching?
(b)        Highlight four ways by which a black Jeans can be bleached.
(c)        State five safety materials for bleaching.

Most candidates were unable to exhibit a thorough knowledge of bleaching agents involved in bleaching process instead they were mentioning the trade names of the finished products.  These wrong responses made the candidates to lose substantial marks.  They are expected to respond to the question in the following manner:

(a)        It is the process used to remove colour from a dyed fabric to form a desired pattern.
            It is a process of obtaining an evenly white fibre, yarn or fabric with the use of
            bleaching agents.


            It is the process of removing the grey colouring matter from raw cotton goods with           the use of chemicals to make them white.
            It is the process of whitening or removing the natural colour of textile fibres, yarns            and fabrics by the treatment of chemicals.
(b)        (i)         Through sodium hypochlorite bleaching;
            (ii)        through oxidation bleaching;
            (iii)       through hydrogen peroxide bleaching;
            (iv)       through sodium chlorite bleaching;
            (v)        through fluorescent whitening bleaching;
            (vi)       through sodium hydrosulphite bleaching;
            (vii)      through caustic soda/sodium hydroxide bleaching;
            (viii)     through calcium hypochloride bleaching.

(c)        (i)         Industrial/rain boot;
            (ii)        Hand/rubber gloves;
            (iii)       Apron/Overall;
            (iv)       Nose mask/guard;
            (v)        Soap/detergent;
            (vi)       Water;
            (vii)      Mouth mask/guard;
            (viii)     Pomade/Petroleum jelly;
            (ix)       Safety glasses/Sun shade.



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