Gel pen

A gel pen uses ink in which pigment is suspended in a water-based gel.^[1] Because the ink is thick and opaque, it shows up more clearly on slick surfaces than the typical inks used in ballpoint or felt tip pens. Gel pens can be used for many types of writing and illustration.

The general design of a gel pen is similar to that of a regular ink based pen, with a barrel containing the writing mechanism and a cap, and a reservoir filled with ink. At the end of the ink tube is an ink "follower", made of more viscous gelled material which is usually translucent and follows the water-based ink. The follower mainly prevents leakage and back flow of the ink. The barrels can be created in many different sizes and designs; some have finger grips of rubber or plastic. The size of the nib or pen tip ranges from 0.18 millimetres (0.0071 in) to 1.5 millimetres (0.059 in).