Fraction ink transfer

Figure 3. Typical ink transfer (top) and fractional ink transfer (bottom) curves for newsprint printed at 4.6 m/s and 15.4 kN/nt in a GFL rotary press (%).

The equation is fitted to the fractional ink transfer curve in order to maintain residual error homogeneous over the whole range of ink weights on the printing plate. The estimates obtained for the parameters k, b, and f reflect fundamental printing characteristics of the paper. For example, as shown in Figure 5 the k parameter is a measure of the smoothness of the paper under printing conditions. 

Figure 6. Change in fractional ink transfer with a shift in parameters k, h, and f in the Walker-Fctsko equation equal to one standard deviation about their mean fitted values for 29 printings of newsprint (8).

Under the same printing conditions and taking the effective pore radius, void fraction, and tortuosity of a coated paper to be about 0.2 pm, 0.3 and 5, respectively, the calculated hydraulic impression becomes 0.2 pm. Thus, for coated papers the total amount of ink impressed is a small fraction of the amount of ink transferred to the paper during printing. In other words, the immobilization of ink is predominant in the transfer of ink to newsprint, while the free ink film split is predominant in the case of coated papers. 

---