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Creating Paints/Colors outside of Visible Range?

  1. Jun 3, 2015 #1

    WWGD

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    Hi, hope this is not too dumb:
    Is it possible to create paint or clothes whose color is outside of the visible range (of course, we need to then store them in receptacles within the visible range )? Is a substance/object's "natural color" (I guess this is the color in which it either appears in nature, or its "standard design color"--not sure how to define it ) related to the physical/chemical characteristics of the substance? I guess when an object's color is red, then it reflects every color other than red. I would think this property would be related to the internal composition of the substance So we then need to create an object that reflects all colors in the visible range?
    Thanks.
     
  2. jcsd
  3. Jun 4, 2015 #2

    russ_watters

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    Most objects/paints have "colors" outside the visible range - we just can't see them.
    Yes.
    No, a red object absorbs every visible color except red, which it reflects. It's the opposte for transparent things (glass/filters).
     
    Last edited: Jun 4, 2015
  4. Jun 4, 2015 #3
    As Russ pointed out, it's more like the other way around. But even this is a simplification. A red object reflects red better than other colors. But most likely it reflects the the other colors as well, just not so well. This include "colors" outside the visible range.
    If you shine a red laser pointer on blue, green etc objects you can still see the spot in most cases. It may be faint, much fainter than the spot form a red object.

    However, if you mean some ideal objects that reflect only UV for example, they will still be visible, you don't need to worry about storing them.
    They will be black.
     
  5. Jun 4, 2015 #4

    Andy Resnick

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    I'll just add that the idea of 'color' is meaningless when discussing non-visible light. Wavelength, yes; color, no. Better to discuss 'spectral features', for example: "Russian military paints have a reflectance peak at 9.6 um, while US military paints have a reflectance peak at 10.2 um."
     
  6. Jun 4, 2015 #5
    Fluorescent colors reflect an unusually high amount of ultraviolet light as well as its main color such as orange or green on safety vests, posters, etc. These wavelengths are not conventionally visible but our eyes perceive some sort of "energy" there, translates this to intensity and thus the color looks more intense / brighter than it ought to given ambient illumination.

    So my point is that there are already examples of color which are deliberately outside of our visible range. Not sure of this can be bought in paint cans though.

    Some flower petals reflect their regular colors as well as ultra violet. Some insects can see these frequencies directly and use them for identification and targeting. It has been relatively recently discovered that some arctic deer can see ultraviolet frequencies to identify subtle differences in grass vegetation and foliage from afar. This is the first time mammals have shown this ability outside of insects and birds. Just some more interesting anecdotes that may not help your quest.

    You may want to look at the fabrication of fluorescent paints.
     
  7. Jun 5, 2015 #6

    blue_leaf77

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    A black colored object is very likely to reflect wavelengths outside the visible range which we can't see. So yes, it's very possible to realize such a paint - black colored paint.
     
  8. Jun 5, 2015 #7

    WWGD

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    But black is reflected and it is not outside of the visible range. EDIT Black may be the absence of color, but it is still visible.
     
    Last edited: Jun 5, 2015
  9. Jun 5, 2015 #8

    blue_leaf77

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    What we say as black is actually our eyes' (or probably brain's) perception for the absence of visible signal, we can see black object but that doesn't mean our eyes "click" when seeing it, we can tell a black object just because the other things surrounding this object have colors. There is no region in the EM spectrum which can be associated as black, black simply means no or very small amount of visible light. Our black may be different from other species' black. So your first statement is not true because again no wavelength can be associated as black.
     
  10. Jun 5, 2015 #9

    russ_watters

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    No. By definition, as the absence of color, black is not visible. If you see and object and think it looks "black", that just means that it really isn't quite black.

    In any case, none of that had anything to do with what blue_leaf said. The point is that an object that is black (does not reflect light in the visible frequency range) may well reflect light outside of the visible range, making it "colored" in the UV.
     
  11. Jun 5, 2015 #10

    blue_leaf77

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    Well I guess we have a slightly different interpretation of what visible means. I prefer to define visible as our eyes being able to detect its presence, a crystal clear glass is hard to detect and hence hardly visible, so is a magician's black coat in front of pitch dark stage curtain, but a black object sitting in a white background is easy to recognize.
    That's what I pointed out, though.
     
  12. Jun 5, 2015 #11
    'Black' is an absence of photons in the visible spectrum which are being emitted/reflected by the object.
    However this does not mean a black object is invisible.
    Your brain can distinguish (it 'sees the difference'), between the low photon emission of the black object contrasted with other brighter objects.
     
  13. Jun 5, 2015 #12

    WWGD

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    Yes, I was referring to black being distinguishable, I misspoke when I said visible. I am looking for a color one cannot perceive/detect/distinguish, neither directly nor indirectly. While black is th absence of distinguishable signal, I can indirectly detect that there is some object tied to the perception of black around it. If someone is wearing a shirt that my eyes/brain interpret as being black, I do know there is some object there that I can perceive, that induces the interpretation of "black" in my pereceptive apparatus .I am obviously not a physicist, so , while I d try, I may not get every subtlety right the first time around, though I hopefully will eventually get it. How about having a paint reflecting only colors in the UV-or above frequency range or Infra-red or below frequency range? Conversely, is there anything I could do to, e.g., make radio waves visible? Just curious, I don't have any specific goal in mind, just trying o escape my little world of ignorance.
     
    Last edited: Jun 5, 2015
  14. Jun 5, 2015 #13

    blue_leaf77

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    No color that cannot be perceived by us, ok it's about definition I think. I guess what you mean is something that cannot be represented as RGB values by any mean. However let's agree that color is what we usually represent as either RGB, CMYK, and so on (so black is a color, but not a wavelength).
    Anyway, I can't seem to understand what you mean by perceiving directly/indirectly.
    Such a paint will look black to us. I think there do exist substance having mentioned properties and those objects must be, again, black colored.
     
  15. Jun 5, 2015 #14

    WWGD

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    I hope I am not spouting nonsense here; thanks for your patience with a newbie. By perceiving, I mean I know there is some object associated to my perception of black. But I cannot visually perceive , neither directly nor indirectly, the presence of any type of EM waves. I will look up RGB values and CMYK, to try to ask a better-informed question.
     
  16. Jun 5, 2015 #15

    blue_leaf77

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  17. Jun 5, 2015 #16
    Not with pigments, but you could electronically sample radio waves and translate their properties into visual signals emitted by devices such as LEDs.
    In fact conventional TV broadcasting uses radio frequencies which contain information that the receiver translates to visible images.
     
    Last edited: Jun 5, 2015
  18. Jun 5, 2015 #17

    russ_watters

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    Don't IR and UV qualify based on that description? Unless, as said above we define "color" to be light in the visible range, which would make what you are looking for a self-contradiction.
    I'm sure it is possible. Not sure if this is what you describe: http://www.nissenmarkers.com/product/ultraviolet/
    Well, that's a very different question: radio waves are not visible, so to make them visible, you would have to convert them to visible light. There are a number of direct and indirect ways to do that, but which applies depends on your constraints. That's what fluorescence is: the absorption of one frequency of radiation and emission of a different -- typically UV to visible as in fluorescent lights. http://en.wikipedia.org/wiki/Fluorescence
     
  19. Jun 5, 2015 #18

    WWGD

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    Thanks all for your help and patience.
     
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