Abstract: A process for crimping filaments by treating the filaments which are to be crimped, and are carried by a heated gas, in a first treatment chamber, and intermingling the heated filaments in an extended second treatment chamber, from which the gas carrier medium is drawn off through longitudinal slots radially to the direction of travel, wherein only sufficient gas is allowed to flow axially with the crimped filaments from the second treatment chamber that the travel of the crimped filaments is not impeded, while the bulk of the carrier gases is drawn off radially from the second treatment chamber. It is advantageous to draw off the carrier gas in the upper part, which comprises from about 25 to 75%, preferably from 40 to 60%, of the total length of the longitudinal slots of the second treatment chamber.

Abstract: Filaments or filament bundles, which are conveyed by a heated gas, are crimped by treating them in a preheat chamber and crimping them in an elongate chamber from which the heated gas medium issues through longitudinal slits. A stream of cold gas is made to impinge on the outside of the lower one-third of the elongate chamber without allowing significant amounts of this cold gas to enter the said chamber. The resulting filaments or filament bundles have very good dyeing characteristics.