Invisible ink pens are just as cool now as they were when ... the writing may not be as clear or visible under the UV light." ...

Maleden Invisible Ink Pens. These top-sellers are super popular among Yahoo readers this year, and for good reason. Creating cryptic messages is loads of fun for both kids and the — ahem — young at ...

Highlighter pens contain chemicals that absorb visible light as well as ultraviolet (UV) light, which humans cannot see. The UV light “excites” the electrons in the ink’s molecules and ...

while a different wavelength of UV light reacts with the ink to make it disappear again. You use a light pen that you're given when you get your tattoo to activate it and deactivate it ...