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." ...

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 ...

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 ...

What's great about these invisible ink pens is they come with batteries ... When used on dark or heavily textured paper, the writing may not be as clear or visible under the UV light." At this price, ...