Ink

Ink is a liquid or paste containing pigment or dye that deposits color on a surface for writing, drawing, or printing. Its ingredients control color, flow, drying, and durability.

Pigment: A finely divided, insoluble substance that gives materials color or opacity. Pigments provide color without dissolving in the ink's carrier.
Capillary action: The movement of a liquid through narrow spaces caused by surface forces and adhesion. Capillary action draws ink through fountain-pen feeds and into paper fibers.
Fountain pen: A reusable pen that feeds liquid ink to a nib from an internal reservoir. Fountain pens use low-viscosity inks designed to flow through narrow channels.
Graphite: A crystalline form of carbon used as the marking material in ordinary pencils. Graphite marks by depositing solid particles, while ink leaves liquid-carried color.
Dye: A colored substance that dissolves in a liquid and can impart color to a material. Dyes dissolve in ink, unlike the suspended particles used in many pigment inks.
Surface tension: The tendency of a liquid surface to resist deformation because of cohesive molecular forces. Surface tension influences whether ink wets a surface or beads up.
Ballpoint pen: A writing instrument that transfers thick ink through a rotating ball at its tip. Its viscous ink resists leaking while the ball meters it onto paper.
Chalk: A soft marking material, commonly calcium carbonate or gypsum, applied as a powdery solid. Chalk transfers as a friable solid rather than flowing from a liquid carrier.
Solvent: A liquid that dissolves a solute or carries dispersed substances in a solution. The solvent carries colorants and affects how quickly ink flows and dries.
Absorption: The uptake of one substance into the interior of another. Absorption carries some inks into porous paper, shaping their edges and drying.

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