The ink separated from the refill of faded pen uses special fluorescent ink and special fluorescent agent, and the handwriting written by this ink is no different from that of ordinary signature pen. Its principle is to use the color rendering factor of ink to oxidize with oxygen in the air.
Fading pen refers to a pen that can't see the handwriting under normal light, but can only see the handwriting under ultraviolet radiation. Generally used to mark items or write statements that people don't want to see easily.