Roller ball pens or roll pens are

pen A pen is a common writing instrument that applies ink to a surface, usually paper, for writing or drawing. Early pens such as reed pens, quill pens, dip pens and ruling pens held a small amount of ink on a nib or in a small void or cavity wh ...

s which use ball point writing mechanisms with water-based liquid or gelled

ink Ink is a gel, sol, or solution that contains at least one colorant, such as a dye or pigment, and is used to color a surface to produce an image, text, or design. Ink is used for drawing or writing with a pen, brush, reed pen, or quill. Thicker ...

, as opposed to the oil-based

viscous 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 inte ...

inks found in

ballpoint pen 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". ...

s. These less viscous inks, which tend to saturate more deeply and more widely into

paper Paper is a thin sheet material produced by mechanically or chemically processing cellulose fibres derived from wood, rags, grasses or other vegetable sources in water, draining the water through fine mesh leaving the fibre evenly distrib ...

than other types of ink, give roller ball pens their distinctive writing qualities. The writing point is a tiny ball, usually 0.5 or 0.7 mm in

diameter In geometry, a diameter of a circle is any straight line segment that passes through the center of the circle and whose endpoints lie on the circle. It can also be defined as the longest chord of the circle. Both definitions are also valid fo ...

, that transfers the ink from the reservoir onto the paper as the pen moves.

Advantages

There are two main types of roller ball pens: liquid ink pens and gel ink pens. The 'liquid-ink' type uses an ink and ink supply system similar to a

fountain pen A fountain pen is a writing instrument which uses a metal nib to apply a water-based ink to paper. It is distinguished from earlier dip pens by using an internal reservoir to hold ink, eliminating the need to repeatedly dip the pen in an in ...

, and they are designed to combine the convenience of a

with the smooth "wet ink" effect of a

. The 'liquid-ink' type rollerball pens were introduced in 1963 by the Japanese company Ohto. The gel ink type rollerball pens were patented in 1982 by Sakura Color Products. Gel inks usually contain

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 ...

s, while liquid inks are limited to

dyestuff A dye is a colored substance that chemically bonds to the substrate to which it is being applied. This distinguishes dyes from pigments which do not chemically bind to the material they color. Dye is generally applied in an aqueous solution and ...

s, as pigments will sink down in liquid ink (

sedimentation Sedimentation is the deposition of sediments. It takes place when particles in suspension settle out of the fluid in which they are entrained and come to rest against a barrier. This is due to their motion through the fluid in response to the ...

). The thickness and suspending power of gels allows the use of pigments in gelled ink, which yields a greater variety of brighter colors than is possible in liquid ink. Gels also allow for the use of heavier pigments with metallic or glitter effects, or opaque pastel pigments that can be seen on dark surfaces. Liquid ink roller ball pens flow extremely consistently and skip less than gel ink pens do. The lower viscosity of liquid ink increases the likelihood of consistent inking of the ball, whereas the higher viscosity of gel ink produces "skipping", that is, occasional gaps in lines or letters. In comparison to ballpoint pens, * Rollerball pens have a unique ink flow system for an even, high-performance writing experience. * Less pressure needs to be applied to the pen to have it write cleanly. This permits holding the pen with less stress on the hand, saving energy and improving comfort. This can also translate to quicker writing speeds. This is especially true of liquid ink pens. * The inks usually have a greater range of colors due to the wider choice of suitable water-soluble dyes and/or to the use of pigments. * They tend to write more clearly than ballpoint pens do.

Disadvantages

There are a number of disadvantages inherent to roller ball pens: * Roller ball pens with liquid-ink are more likely to "bleed" through the paper. Liquid ink is more readily absorbed into the paper due to its lower

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 inte ...

. This viscosity also causes problems when leaving the tip on the paper. The bleed-through effect is greatly increased as the ink is continually absorbed into the paper, creating a blotch. This does not affect gel-ink roller ball pens as much. This is one way through which the thickness of gel-ink gives it an advantage, in that it isn't as prone to being absorbed. Though the bleed-through effect of a gel-ink roller ball is greater than that of a ballpoint, it is usually not too significant. * Roller ball pens generally run out of ink more quickly than ballpoints because roller balls use a greater amount of ink while writing. This is especially true of liquid-ink roller balls, due to gel ink having a low absorption rate as a result of its thickness. Neither lasts as long as a ballpoint. * Uncapped roller ball pens are more likely to leak ink when, for example, placed into a shirt pocket, but most pens include caps or other mechanisms to prevent this from happening. * A roller ball tip is more likely to clog and jam when writing over

correction fluid A correction fluid is an opaque, usually white fluid applied to paper to mask errors in text. Once dried, it can be handwritten or typed upon. It is typically packaged in small bottles, lids attached to brushes (or triangular pieces of foam) th ...

that has not yet completely dried. This often renders the ink cartridge useless.

Standards

The

International Organization for Standardization The International Organization for Standardization (ISO ) is an international standard development organization composed of representatives from the national standards organizations of member countries. Membership requirements are given in Art ...

has published standards for roller ball pens: ; ISO 14145-1:1998: Roller ball pens and refills – Part 1: General use ; ISO 14145-2:1998: Roller ball pens and refills – Part 2: Documentary use (DOC) To comply to the ISO 14145-2:1998 documentary use standard the following has to be established by an ISO/IEC 17025 accredited laboratory: * Erasure resistance – The surface of the testing paper shall show clear evidence of damage before the line is rendered invisible when tested. *

Ethanol Ethanol (abbr. EtOH; also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound. It is an alcohol with the chemical formula . Its formula can be also written as or (an ethyl group linked to a ...

resistance – The line shall remain visible when tested with a 50% aqueous ethanol solution (volume fraction). *

Hydrochloric acid Hydrochloric acid, also known as muriatic acid, is an aqueous solution of hydrogen chloride. It is a colorless solution with a distinctive pungent smell. It is classified as a strong acid Acid strength is the tendency of an acid, symbol ...

resistance – The line shall remain visible when tested with a 10% aqueous hydrochloric acid solution (mass fraction). *

Ammonium hydroxide Ammonia solution, also known as ammonia water, ammonium hydroxide, ammoniacal liquor, ammonia liquor, aqua ammonia, aqueous ammonia, or (inaccurately) ammonia, is a solution of ammonia in water. It can be denoted by the symbols NH3(aq). Although ...

resistance – The line shall remain visible when tested with a 10% aqueous ammonium hydroxide acid solution (mass fraction). * Bleaching resistance – The line shall remain visible when tested with an aqueous 3% freshly made solution of chloramine-T (mass fraction). * Water resistance – The line shall remain visible when tested with water. * Light resistance – The line shall remain visible when tested with light. Most roller ball refills comply to the ISO 14145-2:1998 standard and are approved for documentary use.

Uses

Former MI-6 agent Richard Tomlinson alleges that ''

Pentel is a privately-held Japanese manufacturing company of stationery products. The name is a combination of the English words ''pen'' and ''tell'' (as in, telling a story). Pentel is also the inventor of non-permanent marker technology. Most Pente ...

Rolling Writer'' roller ball pens were extensively used by SIS agents to produce secret writing (invisible messages) while on missions. The Ohto Model CB-10F Ceramic Roller Ball Pen was used at the 1990 Economic Summit of Industrialized Nations.

References

External links