A gel pen uses ink in which

pigment A pigment is a colored material that is completely or nearly insoluble in water. In contrast, dyes are typically soluble, at least at some stage in their use. Generally dyes are often organic compounds whereas pigments are often inorganic compou ...

is suspended in a

water Water (chemical formula ) is an inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as ...

-based

gel A gel is a semi-solid that can have properties ranging from soft and weak to hard and tough. Gels are defined as a substantially dilute cross-linked system, which exhibits no flow when in the steady-state, although the liquid phase may still di ...

. Because the ink is thick and

opaque Opacity or opaque may refer to: * Impediments to (especially, visible) light: ** Opacities, absorption coefficients ** Opacity (optics), property or degree of blocking the transmission of light * Metaphors derived from literal optics: ** In lingui ...

, it shows up more clearly on slick surfaces than the typical inks used in

ballpoint A ballpoint pen, also known as a biro (British English), ball pen ( Hong Kong, Indian and Philippine English), or dot pen (Nepali) is a pen that dispenses ink (usually in paste form) over a metal ball at its point, i.e. over a "ball point" ...

felt tip A marker pen, fine liner, marking pen, felt-tip pen, felt 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 s ...

pens. Gel pens can be used for many types of writing and illustration. The general design of a gel pen is similar to that of a regular ink based pen, with a barrel containing the writing mechanism and a cap, and a reservoir filled with ink. At the end of the ink tube is an ink "follower", made of more viscous gelled material which is usually translucent and follows the water-based ink. The follower mainly prevents leakage and back flow of the ink. The barrels can be created in many different sizes and designs; some have finger grips of rubber or plastic. The size of the nib or pen tip ranges from to .

Gel inks

Compared to other inks, gel ink has higher melting point

viscosity The viscosity of a fluid is a measure of its resistance to deformation at a given rate. For liquids, it corresponds to the informal concept of "thickness": for example, syrup has a higher viscosity than water. Viscosity quantifies the int ...

, which supports a higher proportion of pigments in the medium. The pigments are typically

copper phthalocyanine Copper phthalocyanine (CuPc), also called phthalocyanine blue, phthalo blue and many other names, is a bright, crystalline, synthetic blue pigment from the group of phthalocyanine dyes. Its brilliant blue is frequently used in paints and dyes ...

and

iron oxide Iron oxides are chemical compounds composed of iron and oxygen. Several iron oxides are recognized. All are black magnetic solids. Often they are non-stoichiometric. Oxyhydroxides are a related class of compounds, perhaps the best known of wh ...

s, and the gel is made up of water and

biopolymer Biopolymers are natural polymers produced by the cells of living organisms. Like other polymers, biopolymers consist of monomeric units that are covalently bonded in chains to form larger molecules. There are three main classes of biopolymers, ...

s, such as xanthan gum and tragacanth gum, as well as some types of polyacrylate

thickener A thickening agent or thickener is a substance which can increase the viscosity of a liquid without substantially changing its other properties. Edible thickeners are commonly used to thicken sauces, soups, and puddings without altering their t ...

s. The pigments are opaque, and gel pens are available in several bright and pastel colours, as well as opalescent,

metallic Metallic may be a reference to: *Metal *Metalloid, metal-like substance *Metallic bonding, type of chemical bonding *Metallicity, in astronomy the proportion of elements other than helium and hydrogen in an object *Metallic color, a color that g ...

, and

glitter Glitter is an assortment of small, reflective particles that come in a variety of shapes, sizes, and colors. Glitter particles reflect light at different angles, causing the surface to sparkle or shimmer. Glitter is similar to confetti, sparkle ...

y colours which show up clearly on dark paper. Many gel inks are water resistant, and are not washed away by water once the ink has dried. Fraud resistant gel ink is unaffected by solvents such as acetone, and resists check washing. Gel ink resists an analytical method commonly used to assess the potential age of ink for forensic purposes. The

United States Secret Service The United States Secret Service (USSS or Secret Service) is a federal law enforcement agency under the Department of Homeland Security charged with conducting criminal investigations and protecting U.S. political leaders, their families, and ...

has maintained the International Ink Library for many decades. Because manufacturers change their ink formulas slightly from year to year,

thin-layer chromatography Thin-layer chromatography (TLC) is a chromatography technique used to separate non-volatile mixtures. Thin-layer chromatography is performed on a sheet of an inert substrate such as glass, plastic, or aluminium foil, which is coated with a t ...

(TLC) can be used on ink from traditional pens to trace the manufacturer and date of manufacture of most inks. The pigments in gel ink do not dissolve, and therefore cannot be analyzed with TLC.

History

The first gel pens were produced by

Sakura Color Products is a Japanese manufacturing company headquartered in Morinomiya-chūō, Chūō-ku, Osaka, which produces a variety of stationery products as well a wide range of art materials. Nevertheless, Sakura is mostly known by its marker pens, such as th ...

of Osaka, Japan. The first gel pen to be released commercially was the Ball sign 280, which was sold by Sakura Color Products in Japan. Their first product which became available in America in the late 1980s was the Gelly Roll. Following this, Crayola began producing pens with thicker bodies, marketing them to children. The gel of these pens were made up of metallic sparkles and fluorescent colors, popular among artists for their easy control and smooth drawing capability.

References

{{Pens Writing implements Pens

Gel inks

History

See also

References