What makes fluorescent colours so bright?

Have you ever wondered why fluorescent (aka neon or day-glow) colours look so bright? This short guide will explain everything.

Fluorescent ink contains pigments that 'fluoresce'. Essentially, they convert some invisible UV light into visible light. 

The fluorescent pigments absorb the UV-light, that cannot be seen by the human eye, and re-emit at a wavelength we can see. It's converted to the wavelength that matches the fluorescent pigment colour.

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Because humans can't see the original UV light, a fluorescent ink looks like it is glowing.

This makes fluorescent colours appear much brighter than conventional colours. Cool eh!

Like this:

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This image shows the whole electromagnetic spectrum and how much of it is visible light.

As you can see, there are lots of wavelengths the human eye cannot see. 

Fluorescent ink converts some of the UV light to visible light.