Dyeing machine control using in‐line colour measurement Part 2: On‐line control of dye exhaustion rate

Abstract

Part 1 of this paper reported a novel method of dyebath analysis, based on an in‐line analysis cell with links to a computer‐based match prediction system that included compensation for changes in dyebath temperature. We now describe the cell's use in feedback control of the rate of uptake of dye from the dyebath by controlling the dyebath temperature in conventional (all‐in) and continuous‐addition dyeing. For all‐in dyeing, a high level of control was achieved, allowing experimental verification of the theoretical result that a quadratic exhaustion profile gives the best levelness. When dye was added continuously, a linear exhaustion profile proved to be the most robust and gave the best levelness with either linear or exponential addition of dye.