Colorants: These determine the color of the ink and are categorized into dyes and pigments, typically accounting for 0.5%–10% of the total composition. Dyes offer vibrant colors and are less likely to clog printheads, though they generally have poor lightfastness and water resistance. Pigments, by contrast, offer superior durability, making them well-suited for outdoor printing applications.
Solvents: These serve to dissolve or disperse the colorants. Water-based inks primarily use water and water-soluble solvents (such as glycols), while solvent-based inks utilize organic solvents, which can make up as much as 90% of the formulation.
Surfactants: These adjust the surface tension of the ink, ensuring that ink droplets spread more evenly across the paper surface.
Additives: This category includes humectants (to prevent printhead clogging), pH adjusters, preservatives, and drying agents; although used in small quantities, they play a critical role.
