Basic principles of the dyes addition.
Most modern machines use metered liquid dyes. These dyes are added Late in the system separated from other chemical adds. The best addition point is after the Level Box or before silo and fan pump. In very Dark shades 2/3rds of the dye can be added at the Pulper and the balance color controlled at normal addition point.
If a combination of ADD and CDD is used then they must be separated by at least 2 meters at the addition points.