Marker pen
A marker pen, fine liner, marking pen, felt-tip pen, flow marker, sign pen (in South Korea), vivid (in New Zealand), texta (in Australia), sketch pen (in South Asia) or koki (in South Africa), is a pen which has its own ink source and a tip made of porous, pressed fibers such as felt.[1] A marker pen consists of a container (glass, aluminum or plastic) and a core of an absorbent material... This filling serves as a carrier for the ink. The upper part of the marker contains the nib that was made in earlier times of a hard felt material, and a cap to prevent the marker from drying out.
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Until the early 1990s, the most common solvents that were used for the ink in permanent markers were toluene and xylene. These two substances are both harmful[citation needed] and characterized by a very strong smell. Today, the ink is usually made on the basis of alcohols (e.g. 1-Propanol, 1-butanol, diacetone alcohol and cresols).
Markers may be waterproof, dry-erase, wet-erase (e.g. transparency markers), or permanent.