Today we continue a six-part series on lightfastness, which is
the resistance of various pigments and media to fading as a
result of exposure to light. Highlighter markers fare very
poorly. Fluorescent highlighters use relatively unstable
colorants that convert invisible ultraviolet light into light
that you can see. That conversion of UV to visible light adds
light; that’s why a yellow highlighter stripe can appear lighter
than the white of the paper. But the effect lasts only as long
as the molecules hang together. The blue, pink, and orange
highlighters vanished, and the yellow highlighter darkened to a
brown. Regular art markers, like these Berol Prismacolor brand
Markers, didn’t do well. They faded away to the palest tints.
For this reason, if you have a marker drawing that you like,
don't leave it exposed to light for very long. Put it in a
drawer or between the pages of a book! Why Do Colors Fade? The
reason colors fade is that the colorant molecules break down
when they are exposed to light, especiall