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Most people consider ink for use in drawing or writing with a pen or brush. However ink can be of a paste form, and this kind of ink is used most extensively in letterpress and lithographic printing. Ink manufacturers produce ink by using three types of ink making materials: a colorant (about 1-5 weight percent), a solvent (liquid vehicle, very often water) and a binder. Often further additives are used to prevent the ink from drying too quickly in the pen. The colorant can be either a dye (soluble molecules) or a pigment (colored powder, which needs to be finely dispersed). In magic markers, fluorescent dyes are often used. These convert the ultraviolet part of daylight into visible radiation, thus strengthening the color impression.
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