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BATCH DYEING OF COTTON WITH REACTIVE DYES 343
consumption of dyes, salt and alkali. Figures 16.4 and 16.5 allow comparison of
typical dyeing procedures in which the alkali for fixation is added to the dyebath in
one portion (Figure 16.4), or gradually using a variable speed metering pump (Figure
16.5). For the latter method, the rates of exhaustion and fixation are relatively
constant.
100 100
(b)
80 80
Exhaustion/% 60 (a) 60 Fixation/%
40
(b) 20
40
(a)
20
00Exhaustion/% Fixation/%
0 20 40 60 80 100
Time/min
Figure 16.4 Dyebath exhaustion (solid line) and dye fixation (dotted line) as a function of
time during dyeing with low (a) and high substantivity (b) reactive dyes; alkali addition at
30 min
100 100
80 80
60 60
40 40
20 20
00
0 20 40 60 80 100
Time/min
Figure 16.5 (See also Figure 10.3) Dyebath exhaustion (solid line) and dye fixation (dotted
line) as a function of time during dyeing with a reactive dye, with metering of the alkali
solution
