The principle of automatic fading pen is:

It is reported that the pen uses special ink. The handwriting written in this ink is no different from that of an ordinary signature pen. Its principle is that the color-developing factor of ink reacts with oxygen in the air, and when the color-developing factor in ink changes, it will fade.

The police further explained that depending on the material, temperature, humidity and writing speed, the handwriting will naturally fade within 15 minutes to 2 days.

The formula of this kind of ink is the core trade secret of the factory, but it is basically made of volatile chemicals such as alcohol, which makes the ink fade without trace by using the principle of volatilization.

According to the manufacturer who specializes in manufacturing this fading pen, the fading pen is mainly used for temporary writing and marking in textiles, handicrafts and other industries, and later extended to copybook copying, graffiti on city walls, children's painting and so on.