Inks

Inks are liquids or pastes used to apply color to a surface. They consist of a colorant dispersed or dissolved in a vehicle, together with binders and additives. The colorant can be a pigment (finely divided solid particles) or a dye (a soluble colorant). The vehicle carries the colorant and evaporates or cures after application, while binders help attach the color to the substrate and control flow, drying, and adhesion.

Common categories include writing inks used in pens (such as ballpoint, fountain, and gel inks) and printing inks used in commercial print and digital display technologies. Printing inks are further diversified by process: offset, gravure, flexography, screen printing, and inkjet inks for digital printers. Each category uses different formulations to suit the surface, application method, and durability requirements.

Inkjet inks illustrate the diversity of modern inks. They are typically water-based or solvent-based, and may be dye-based or pigment-based. Dye inks provide bright colors but lower lightfastness; pigment inks use dispersed solid particles and generally offer greater permanence and water resistance, at higher cost and with different flow characteristics.

History and development: inks have evolved from carbon black and plant dyes to synthetic pigments and resins. Modern inks aim for precise color, fast drying, carrier compatibility with substrates, and stability during storage and use.

Environmental and safety aspects include concerns about volatile organic compounds, heavy metals in some pigments, and waste management. Inks are designed to meet standards for archival quality, print permanence, and recyclability of the substrates they are used on.