Rollerball pen
From Wikipedia, the free encyclopedia
Rollerball pens are pens which utilize ball point writing mechanisms with water-based or gel-based ink, as opposed to the oil-based inks found in ballpoint pen. The characteristics of these less viscous inks, which tend to saturate more deeply and more widely into the paper than other types of ink, give rollerball pens their distinctive writing qualities.
The rollerball pen was initially designed to combine the convenience of a ball pen with the smooth "wet ink" effect of a fountain pen.
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[edit] Types
There are two types of rollerball pens: those that use a liquid ink and those that use a gel containing ink.
Gel rollerball pens use a jelly-like ink: the ink sets just after it is applied to the paper and is no longer being "rolled" around. Because their inks set so quickly, gel inks do not sink into the paper as much as liquid ink. With a gel ink, one may often write on both sides of a piece of paper. But with a liquid ink, the ink will often flow through enough to make the second side unusable.
Gels may contain pigments, whereas liquid inks contain dyestuff, as pigments will sink down in liquid ink (sedimentation). This allows for brighter colors than liquid ink, so gel-based pens are available in a brighter and wider range of colors than liquid ink pens. Also, pigments allow effects like glitter inks or writing on dark surfaces, because they reflect light directly, whereas dyestuff inks need a white background. Due to the smaller size of dyestuff molecules, light will mostly pass through them and needs a reflective background. The color effect is only generated because dyes filter out specific wavelengths of ligtht.
[edit] Advantages over a 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 ink is brighter.
[edit] Disadvantages
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 the 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 does not penetrate deeply into the paper. Also, the rollerball cannot give vibrant colors as well as an ordinary ballpoint.
The problem with gel inks is that they do not flow as readily as a liquid ink. This increases the likelihood of intermittent inking, where the flow of ink will randomly cease.
One other point worth noting is that rollerball pens usually do not last as long as a regular oil-based ballpoint pens because the liquid water-based ink is dispensed at a quicker rate to give the bolder writing.
