Ink is a liquid or paste that contains pigments or dyes and is used to color a surface to produce an imagetext, or design. Ink is used for drawing or writing with a penbrush, or quill. Thicker inks, in paste form, are used extensively in letterpress and lithographic printing.

Ink can be a complex medium, composed of solvents, pigments, dyes, resinslubricantssolubilizerssurfactantsparticulate matterfluorescents, and other materials. The components of inks serve many purposes; the ink's carrier, colorants, and other additives affect the flow and thickness of the ink and its dry appearance.

In 2011 worldwide consumption of printing inks generated revenues of more than 20 billion US dollars. Demand by traditional print media is shrinking, on the other hand more and more printing inks are consumed for packaging.

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