The Choice of Optimum Dye Exhaustion Profiles in the Direct Control of Dyeing

New developments could substantially increase the practical feasibility of direct control by optical means of the exhaustion of commercial dyeings. This paper examines the preferred form of the exhaustion profile that should be used by such equipment, and the relationship between the rate of bath exhaustion, and the corresponding error in dye deposition in different parts of a textile load has been calculated. It is shown that the maximum permissible rate must fall progressively throughout the exhaustion period. This is contrasted with isoreactive dyeing and related concepts. The relationship between dye deposition error and colour difference is also discussed. Examples are given of practical profiles, the colour differences associated with them, and the operation of a control parameter based on the theory