Abstract: A process for the dyeing of a fibrous article utilizing closed-loop metered dosing of one or more dyes and one or more chemicals that are adjusted in real time as a function of selected monitored parameters of the dyeing bath. The process includes immersing the fibrous article in a heated liquid bath of a solvent medium for the dye wherein the bath has a predetermined pH. Acid is added to the dyeing bath to reduce the pH according to a predetermined profile that is responsive to real-time measurements of dyeing bath pH. Dye is also added to the dyeing bath during dyeing as a liquid concentrate and responsive to real-time calculations of dye uptake by the fibrous article. Dye uptake is calculated periodically by determining in real time during dyeing (1) the solution concentration of the dye in the dyeing bath and (2) the amount of the dye added to the dyeing bath, and then calculating the uptake of dye by the fibrous article therefrom.