Ink

An ink is a liquid containing various pigments and/or dyes used for coloring a surface to produce an image, text, or design. Ink is used for drawing and/or writing with a pen, brush or quill. Thicker inks, in paste form, are used extensively in letterpress and lithographic printing. Ink is a complex medium consisting of comprising solvents, pigments, dyes, resins, lubricants, solubilizers, surfactants, particulate matter, fluorescers, and other materials. The components of inks serve many purposes; the ink’s carrier, colorants, and other additives are used to control flow, thickness, and appearance of the ink when dry.

Early varieties include Egyptian ink, various natural dyes made from metals, the husk or outer covering of beans or seeds, and sea creatures like the cuttlefish (known as sepia). India ink is black and originated in Asia. Iron gall ink was used by many of the old masters for drawing. Walnut ink is erroneously thought to have also been used by old masters, however, there is no proof of this. Walnut inks, if they were used, would have faded fairly quickly and would therefore be unsuitable.

Pigmented inks contain other agents that ensure adhesion of the pigment to the surface and prevent it from being removed by mechanical abrasion. These materials are typically referred to as resins (in solvent-based inks) or binding agents (in water-based inks). Because pigmented inks stay on the surface of paper, less ink is needed to create the same intensity of color as with dye-based inks. Pigmented inks also tend to be more resistant to washing out. For this reason these inks are frequently recommended for applications where erasure is undesirable. Gel inks are particularly resistant to erasure and frequently bear recommendations from forgery experts.

Ink refilling services for printer cartridges are offered by large, official printing companies as well as smaller, "unofficial" refill companies. Customers can often cut printing costs by using refill services from a refill company, or buying the new non-OEM brands instead of refilling. The refilling of ink cartridges and the use of continuous ink supply systems for inkjet printers is very common in most countries, with the exception of the United States. As printer manufacturers control to a great extent, the type of competition that they on retail shelves, the purchasing of devices to ease the use of refill inks is only available online for the most part.