The Efficient Use of Steam and Water in the Continuous Dyeing and Printing of Carpets

All continuous coloration processes for carpet fibres are based on the sequence: Impregnate→Steam fix→Wash‐off Although process optimization may be achieved at the dye‐application stage, lack of attention to the second and third stages may result in poor reproducibility (from laboratory to the bulk scale and from batch to batch), an increase in second quality material, and a wastage of water and energy. The steam fixation and washing‐off stages have been studied under laboratory conditions to define the compromise between ideal and practically realisable conditions. Variations in steam quality (temperature, air content, degree of turbulence, presence of free water, etc.) are shown to have a profound effect on dye fixation. Subsequent treatments with water of varying efficiency affect, in turn, the handle, appearance and level of wet fastness of the finished carpet. Investigation of steaming and washing‐off conditions used in practice show that these are often far from ideal, partly owing to the design of the equipment and partly due to the lack of sufficiently precise controls leading to an excessive use of both steam and water. Modifications tending to improve process conditions are suggested and where these are not feasible under local circumstances, the effect of dye and auxiliary product selection to minimize the above problems are discussed.