Specific gravity of ink and color rendition of printed matter: The specific gravity of ink serves as a comprehensive gauge of the specific gravity of the ink’s key components, viz., pigments, fillers, and binders. Generally speaking, when combining two inks of different specific gravities for color printing, the larger the specific gravity of the ink, the greater the required quantity, and vice versa. Furthermore, blending multiple inks of varying specific gravities in color printing can lead to stratification due to sedimentation, potentially causing color variation or uneven color rendering during the printing process. The ink may separate, with the lighter components floating to the top. For instance, when combining green ink with lead chrome yellow ink and peacock blue, the ink with the lower specific gravity may rise to the top over time, while the denser ink sinks, resulting in what is known as “floating color.” Hence, it is crucial to stir the prepared ink evenly before pouring it into the ink fountain.

Ink concentration and color rendition of printed matter: The ink concentration, also referred to as the tinting strength of the ink, reflects the degree of dispersion of the ink and the pigment content within the ink. Factors such as pigments, linking materials, fillers, and additives influence the ink concentration. In general, the higher the degree of pigment dispersion, the higher the ink concentration; conversely, the greater the pigment content in the ink, the higher the ink concentration.