Fluorescent—or "neon"—colors do that, too, but they have an additional trick. Fluorescent colors also absorb and convert ultraviolet rays, which are invisible, and convert them into visible light. Fluorescence shifts energy in the incident illumination from shorter wavelengths to longer (such as blue to yellow) and thus can make the fluorescent color appear brighter (more saturated or lighter in luminance) than it could possibly be by reflection alone. The absorbed energy excites electrons in the pigment molecules to a higher energy level, which then relax back to their ground state by emitting light at a longer wavelength than that absorbed, resulting in a visible glow
As a result, your eye perceives a far more saturated color or a tone that's higher in tone relative to the white paper they're drawn or painted on.
Ultraviolet light is usually present in outdoor light, whether direct sunlight or overcast. Without a source of short-wavelength light (like a black light), the fluorescent pigments won't stand out. As soon as you add an ultraviolet light source, the fluorescent pigments will appear to glow, while conventional colors remain dull and hardly visible. If a subject is lit only by ultraviolet light and no visible wavelengths, fluorescent colors will appear to glow magically in the dark.
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Interesting. Now, I wonder if underpainting with fluorescent colors might be used to create interesting effects or to brighten an area, create color/complementary interactions.
ReplyDeleteForrest, it might be fun to experiment that idea, but we should keep in mind that fluorescent colors only function in certain kinds of light, and most aren't lightfast.
ReplyDeleteJames, I got confused. I meant to refer to "dayglo" colors. I have read reference to people using these as the basis for underpainting. But it's not clear to me what benefit -- or what the effects are based on how they behave. It does sound interesting.
ReplyDeleteI was jumping around on the web to see the definitions that various fluorescent paint manufacturers present for fluorescent paint, and came across this post by James Gurney. It is the best definition I have come across. One manufacturer I just dropped in on, via the web, appears to assume that you are at least in your third year of earning your BS in physics. (Although, there are few reasons to be pursuing a BS physics degree, unless you are a super dedicated science tinkerer, and don't mind living in a shared apartment with a bunch of people with degrees that also won't earn you a living...)
ReplyDeleteYes, it is as James states. Fluorescent paint is designed to reflect as much incident visible light as is practical. i.e., red light in, red light out: blue light in, blue light out...(mostly) You get it. (Of course, I suppose there is a compromise in doing this, considering that the chemistry of the paint must include the fluorescing components that may not be optimal for reflection in the visible spectrum of light.) In addition, to reflecting colors in the visible spectrum, fluorescent paint is designed to convert a maximum amount of energy outside the visible spectrum of light into visible light. Thus, the viewer of all of this light coming off of the paint will see the reflected light within the visible spectrum, plus visible light that is the result of energy outside of our visible spectrum that is converted into visible light.
Now, if you just read this, and wonder why I would rave about how great James' definition is, then provide another definition, which is more convoluted than the one James posted, well, your not alone. I sit here pondering how wise hitting the "PUBLISH" button below will be. Aw heck, I'm going to hit it.