Based on isothermal exhaustion curves recorded at various temperatures, the
possibility of describing numerically the uptake profile of a dyestuff has
been investigated. Since the exhaustion process is a complex one, its kine
tic parameters depend on the experimental conditions and cannot be used to
characterise a group of curves. The alternative method proposed in this stu
dy is the use of invariant kinetic parameters for describing the exhaustion
of a dyestuff in a dyeing system under various conditions, The concepts ha
ve been applied to the exhaustion of two reactive dyestuffs on cotton. The
results show that all the isothermal exhaustion curves of a dyeing system c
an be described by a unique group of three parameters, n(i), E-i and A(i).