What if you could print an invisible ink that could only be seen with a special light? That’s exactly what fluorescing inks do. Here’s a little primer on how they work: Visible light – the white light that makes up the rainbow of colors – contains wavelengths between 400-700 nanometers (nm). Non-visible Ultraviolet A light ranges just below that, from 315-400 nm. The purple blacklights you might see in indoor laser tag arenas and nightclubs emit filtered low-power UVA light to make décor, white fabrics (and your teeth) glow. That glowing comes from phosphors, which converts invisible UVA light into visible light. That excitement and resulting light is called fluorescence.

 

Fluorescing pigments in commercial large-format printing inks can be visible or invisible on paper, film and metal substrates, then when placed under a blacklight or UVA light, they will emit a strong color, depending on the fluorescing emission wavelength.

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You might think that counterfeiters could simply buy fluorescing inks and easily make fake documents, products or labels, but it’s not that easy. First, CTI ensures that every customer is a legitimate business, and we do not sell small quantities. Second, brands and agencies use machines to read the fluorescing color strength, and a criminal would need that reader and the specification to produce fake prints. Finally, most security prints have layers of features.