Analysis of the factors influencing dye uptake on jet dyeing equipment

Machine parameters that possibly influence the dye-uptake rate on textile jet dyeing equipment are reviewed in this study. Some of these parameters can be adjusted on a pilot-scale jet machine so as to reproduce bulk conditions, whereas others cannot. It was impossible, for example, to simultaneously achieve appropriate values for the nozzle flow velocity and the dyebath circulation time. The fabric–liquor interchange in the storage area of the machine was also different on pilot scale and on bulk scale. Experiments on a pilot machine with a direct dye on cotton yielded, for most cases, no influence of fabric speed and dyebath flow rate on the dye-uptake rate despite high substantivity conditions. Only when the flow rate dropped below 50 dm³ min⁻¹ kg⁻¹, the exhaustion rate diminished approximately proportionally to the square root of the flow rate, probably because of dye depletion in the storage chamber. On the pilot machine, the jet nozzle did not appear to contribute to the overall fabric–liquor interchange. Implications for bulk jet dyeing machines are discussed.