Abstract: Disclosed is a method of rapid dyeing a substrate comprising polyester fibres at a temperature above 100.degree. C. comprising bringing into contact with the substrate an aqueous dyebath containing a mixture of at least two disperse dyes having each individually specific physicochemical properties.

Abstract: The invention provides a process for increasing the affinity for anionic dyes of undyed water-insoluble high molecular weight organic compounds containing groups which can be alkylated, which process comprises reacting the high molecular weight compound with an ammonium salt of the formula: ##EQU1## in which X signifies chlorine or bromine.Y signifies a radical of formula --CH=CH-- or a phenylene radical which is unsubstituted or substituted by up to a total of 2 alkyl groups which may be methyl or ethyl,R.sub.1, r.sub.2 and R.sub.3, independently signify hydrocarbon radicals consisting of aromatic and/or saturated aliphatic units, orTwo of R.sub.1, R.sub.2 and R.sub.3 jointly with the N atom form a heterocyclic ring, which is selected from heterocyclic rings containing one nitrogen atom, two nitrogen atoms and one nitrogen atom and one oxygen atom, and the other signifies a hydrocarbon radical as defined above or a further bond when the ring is unsaturated,The total number of carbon atoms in R.sub.1, R.sub.