Roller Ball Pens

Rollerball pens are writing instruments which use ball point writing mechanisms with water-based liquid or gelled ink, as opposed to the oil-based viscous 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 ballpoint pen with the smooth "wet ink" effect of a fountain pen. 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.


A rollerball pen has two main advantages over a ballpoint pen:

* 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.
* The inks are usually more brightly and variously coloured, due to the wider choice of suitable water-soluble dyes, or to the use of pigments.