Editing Invisible ink (section)

=== Inks visible under ultraviolet light ===
[[File:20 USD in UV light.jpg|thumb|A US$20 bill showing a visible stripe under an ultraviolet light]]
Some inks glow faintly ([[fluorescence|fluoresce]]) when under an [[ultraviolet]] lamp. This is a property of many substances, particularly organic substances and body fluids.

Other inks work in a near opposite way by {{em|absorbing}} ultraviolet light but without fluorescing. When these are used on [[fluorescence|fluorescent]] paper, the inked areas fluoresce less than the surrounding paper area when under an ultraviolet lamp. This is especially a property of inks with a yellow tint.

Some UV-visible inks may be detected on a photocopy, due to the relatively strong ultraviolet component in light from the photocopier scanning head.

Examples of inks revealed by ultraviolet light are:

* [[Laundry detergent]]s containing [[optical brightener]]s
* [[Soap]]
* Body fluids, [[Blood plasma|serum]], [[saliva]]
* Sunscreen
* Lemon juice