Abstract: The invention provides a method for the production of a pigment preparation for coloring linear polyesters in the melt, which comprises forming a concentrate from 20 to 80 parts of pigment and 80 to 20 parts of a polyester which melts between 60.degree. and 160.degree. C., by kneading in the presence of a salt and a solvent or by a flush process, mixing said concentrate with a fibre forming linear polyester, melting the mixture and processing it to granules. The invention also provides the pigment preparation obtained by the process and the linear polyesters colored therewith.

Abstract: A process for the mass coloration or whitening of linear polyesters, wherein the polyester to be colored is mixed, in the solid or fused state, with a preparation consisting substantially of a colorant or fluorescent brightener which is soluble or insoluble in the polyester, and of a polystyrene with a softening point above 100.degree. C, and the resultant mixture, provided it is not already in the form of a melt, is converted into the molten state and formed into shaped articles. Evenly and deeply colored polyesters are obtained.