A gel pen uses ink in which the pigment is suspended in a water-based gel. Because the ink is thick and opaque, it appears more clearly on dark or smooth surfaces than typical inks used in ballpoint pens or felts. Gel pens can be used for many types of writing and illustration. The general design of a gel pen is similar to that of an ordinary ink pen, with a barrel containing the writing mechanism and a cap, and a reservoir filled with ink. Barrels can be created in many different sizes and designs; some have rubber or plastic plugs. The size of the tip or tip of the pen varies from to.
Compared to other inks, the gel ink has a higher viscosity, which favors a higher proportion of pigments in the medium. The pigments are typically copper phthalocyanine and iron oxides, and the gel is water and biopolymers, such as xanthan gum and gum tragacanth, as well as certain types of polyacrylate thickeners. The pigments are opaque and the gel pens are available in several bright, pastel colors, as well as opalescent, metallic and glittery colors that appear clearly on dark paper. Many gelled inks are water resistant and are not removed by water once the ink has dried. Fraud-resistant gel ink is not affected by solvents such as acetone and is resistant to washing.
Ball pens use a dye-based ink ink dissolved in an alcoholic solvent. Compared to Ball Pens, Gel Pens: Another trait of gel ink is that it resists an analytical method commonly used to assess the potential age of ink for forensic purposes. The United States Secret Service has maintained the International Ink Library for several decades. Since manufacturers are changing their ink formulas slightly from year to year, Thin Layer Chromatography (TLC) can be used on traditional pen ink to trace the manufacturer and date of manufacture of most inks . The pigments in the gel ink do not dissolve and can not be analyzed by TLC.