A method and apparatus for supplying liquid mixtures on a mix-on-demand basis for consumptive use, and for maintaining the composition of such mixture on a highly accurate and stable basis. For wet-on-wet processing of fabrics, the processing solution is supplied at start-up on a mix-on-demand basis to precise specifications and is maintained at such precise specifications throughout fabric processing, which involves continuous additions of water by the incoming fabric and removal of solution by the exiting fabric. Recirculation of the solution at a high rate, together with rapid and repetitive measurements of the composition of the recirculating solution enables the solution to be precisely monitored and maintained. Periodic small additions of chemical are injected as necessary to maintain highly stable, accurately controlled process conditions. Extraordinary economies, both direct and indirect, can be realized with the new system.