Abstract: Textile strands are dyed while being bulked or crimped by lengthwise compression. The dyestuff advantageously is supplied in finely divided liquid or preferably solid form and is injected, as by aspiration or by positive pressure methods, into fluid hot enough to vaporize it before such fluid together with such dyestuff comes into contact with strand so treated. Such strand, forwarded with or by flow of hot propellant fluid into a foraminous region in which the strand is confined laterally but from which the fluid may escape except where the strand is compressed into a compact mass, is exposed to the dyestuff by permeation with such fluid. Lateral escape of the propellant fluid is effected, preferably before such exposure, and is utilized to control an operating condition, such as temperature of strand input into and/or speed of removal of strand from the chamber, for improved uniformity of dyeing and bulking or crimping of the strand.