Roller ball pens orroll pens[1] arepens which use ball-point writing mechanisms with water-based liquid orgelled ink, as opposed to the oil-basedviscous inks found inballpoint pens. These less viscous inks, which tend to saturate more deeply and more widely intopaper 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, that transfers the ink from the reservoir onto the paper as the pen moves.
Close up of an extra fine roller ball pen next to something written with it
There are two main types of roller ball pens: liquid-ink pens andgel-ink pens. The "liquid-ink" type uses an ink and ink-supply system similar to afountain pen, and they are designed to combine the convenience of aballpoint pen with the smooth "wet ink" effect of a fountain pen. The "liquid-ink" type rollerball pens were introduced in 1963 by the Japanese companyOhto.[2][3] The gel-ink type rollerball pens were patented in 1982 bySakura Color Products.[2]
Gel inks usually containpigments, while liquid inks are limited todyestuffs, as pigments will sink down in liquid ink (sedimentation). 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.
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 lowerviscosity. 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 overcorrection fluid that has not yet completely dried. This often renders the ink cartridge useless.
Former MI-6 agent Richard Tomlinson alleges thatPentel Rolling Writer roller ball pens were extensively used bySIS agents to produce secret writing (invisible messages) while on missions.[7]
^Tomlinson, Richard (2001),The Big Breach: From Top Secret to Maximum Security, Mainstream Publishing, p. 44,ISBN1-903813-01-8,you will need to buy a $200 roller ball pen.
