These very particular inks have the ability to change color under the influence of relatively intense UV radiation (sunlight, photographic flash, black light, etc.).
Thus, a transparent lacquer changes very quickly from invisible to blue or from invisible to purple, and retains this color for at least thirty seconds.
All combinations from standard shades are possible, a yellow will change to green, a red will change to purple, etc…
These inks can be formulated in all processes, but, to be most effective, the ink thickness must be as great as possible.
