Fast dry gel ink pen uses the principle of the color change of acid-base indicator in acidic or alkaline solution. Besides the principle of acid-base neutralization in chemical changes, other chemical reactions, such as precipitation reaction, redox reaction, complex ion formation, and catalytic reaction, can be used to prepare invisible ink. Its main function is that the handwriting after writing disappears through contact with air or solution. Apparatus can also be used so that the written handwriting disappears.

On the one hand, lies the ink of fast dry gel ink pen, through the improvement of the ink formula, the nib out of the ink, these very fine ink particles can quickly penetrate into the paper.