- Comment Email LikeInouting Pen - Pen -
- Rollerball pens were introduced in the early 1980s. They make use of a mobile ball and liquid ink to produce a smoother line. Technological advances achieved during the late 1980s and early 1990s have improved the roller ball's overall performance.
There are two types of rollerball pens: those that use a liquid ink and those that use a gelled ink.
Gel rollerball pens use a jelly-like ink: the ink thins as it moves past the ball and sets back up just after it is applied to the paper and is no longer being "rolled" around. Because the gel inks set so quickly, they are not absorbed into paper fibers as much as liquid ink. Using a gel ink pen, one may often write on both sides of the same piece of paper. With a pure liquid ink pen, the ink is often thin enough that it will soak through or "bleed" through enough of the entire paper to make the second side of the paper totally unreadable if written on.
Gels usually contain pigments, while liquid inks are limited to dyestuffs, as pigments will sink down in liquid ink (sedimentation). It is the thickness and suspending power of gels that allows the use of pigments in gelled ink. Using pigments (the same pigments that are used in paint) yields a greater variety of brighter colors than is possible in liquid ink, so gel-based pens are available in a brighter and wider range of colors than liquid ink pens. Also, some gel ink pens can use the heavier pigments with metallic or glitter effects, or opaque pastel pigments that be seen on dark surfaces, because their gel ink suspends pigments so well. Writing by liquid ink pens cannot be seen on dark surfaces because inks containing dyes need a light colored, reflective background, due to the fact that dyes do not reflect light by themselves, in the way that pigment particles do. Dye molecules absorb all but a particular wavelength of light, so light must pass through the ink and bounce off a reflective background in order for our eyes to see the color of the ink.
Advantages over ballpoint
A rollerball has two advantages over a ballpoint: first, 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. Second, the inks are usually more brightly and variously colored, due to the wider choice of suitable water-soluble dyes, or to the use of pigments.
There are a number of disadvantages inherent to rollerball pens: first, the ink is more liable to smudge than a ball-point pen's ink because water-based ink dries more slowly. Second, the ink may seep through the paper. Thicker paper must be used with a rollerball pen than with a ballpoint, because the oil-based ink of a ballpoint pen does not penetrate deeply into paper fibers.
Gel inks do not flow as readily as a liquid ink; this increases the likelihood of intermittent inking of the ball, producing "skipping" where the flow of ink will randomly cease.
Rollerball pens generally won't write as long as a ballpoint pen because both gel and liquid water-based inks are dispensed more quickly than oil-based ink.
Oil-based (ballpoint) pens are also far less likely to "leak" ink into a shirt pocket without putting the "cap" back on.
The International Organization for Standardization has published standards for ball point and roller ball pens:
ISO 12756:1998 Drawing and writing instruments -- Ball point pens and roller ball pens -- Vocabulary 
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)
- Post Now!Pen information comment: