Gel pens are specialized writing instruments favored by many graphic artists and teachers for their bold colors and solid lines. Gel pens use the same basic mechanism as roller-type ballpoint pens, but the ink inside is noticeably thicker than standard ballpoint ink. The bright inks used in gel pens are often augmented with aluminum sparkles for added visual punch.

The first gel pens were marketed by the Sakura Color Products Corporation of Osaka, Japan in 1984. Sakura also developed the first water-based gel inks, seeking a modern recreation of the free-flowing inks used in fountain pens. Gel pens soon became popular among graphic artists and architects, who could use the control of a ballpoint pen while getting the brilliant colors of a marker.

Gel pens with oversized bodies for smaller hands also became popular with children. Crayon companies such as Crayola began marketing lines of gel pens with fluorescent colors and metallic sparkles. Art teachers encouraged the use of gel pens to create posters on construction paper. The added sparkles and fluorescent chemicals allowed student to experiment with dark/light effects and black backgrounds.

Gel pens can have a few quirks, however. Leaving the protective caps off gel pens can cause the ink inside to dry quickly, unlike ballpoint pens. A small silicone ball inside the tip of the cap must be in place to form an airtight seal. The mechanism which draws ink through gel pens and into the tip is prone to damage if not handled with care. Users may try to renovate a dry gel pen by tapping on the top or bottom- this is never a good idea. The roller ball assembly could get hopelessly jammed from the impact. Certain paper surfaces are better than others when it comes to using gel pens. It's best to experiment with different types of paper to see how the pen and ink will respond.

If gel pens should go dry, experts suggest rolling the tip in small circles until the ink flows again. Some find that rolling the pen on a thumb or opposite palm will renovate the pen, but results may very and the ink should be washed off immediately to prevent staining. Gel pens do not work well on greasy surfaces, so users should wash and dry their hands thoroughly before using them.