A colour without its own wave length

Discussion in 'General Science & Technology' started by Michael 345, Feb 5, 2023.

  1. Michael 345 New year. PRESENT is 72 years oldl Valued Senior Member

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  3. exchemist Valued Senior Member

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    Interesting. I looked this up and found there is a magenta dye called fuchsine (from the colour of fuchsia), a.k.a. rosaniline hydrochloride.

    This absorbs mainly in the green, leaving the red and blue to be transmitted, hence giving rise to a red/blue mixed colour that our eyes interpret as magenta.
     
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  5. Seattle Valued Senior Member

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    How is this different than the case of yellow? We don't have yellow sensors either.
    Aren't they the same in that they are both combinations and isn't the only reason you don't see
    magenta in a rainbow because red and blue don't appear near each other?

    The green sensors in your eyes are the most sensitive, the blue is the least sensitive with red in the middle regarding sensitivity. Look at a green laser at night compared to a red laser and then a blue laser. Green appears much brighter.

    Magenta has a wavelength in the same sense that yellow has one. They are both combinations so I don't think there is anything unique about Magenta other than our eyes are less sensitive to red and blue when compared to red and green.
     
    Last edited: Feb 5, 2023
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  7. exchemist Valued Senior Member

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    No, there is yellow light in the spectrum, e.g. the sodium D lines are in the yellow region.

    We don't have yellow frequency receptors: yellow light excites both our red and green receptors, which we interpret as yellow. But there are no magenta lines or bands in the spectrum of light.
     
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  8. Michael 345 New year. PRESENT is 72 years oldl Valued Senior Member

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    No, there is yellow light in the spectrum

    Thank you. I thought that was clear in the video

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  9. gmilam Valued Senior Member

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    Interesting that magenta is one of the primary colors used in 4 color process printing. Magenta, Cyan, Yellow and Black.
     
  10. DaveC426913 Valued Senior Member

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    Magenta is the complement of green, which is the midpoint receptor of our RGB visin.
     
  11. exchemist Valued Senior Member

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    Video? Oh yes I see.

    I don’t watch videos - too time-consuming.
     
  12. Pinball1970 Valued Senior Member

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  13. Michael 345 New year. PRESENT is 72 years oldl Valued Senior Member

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    Colours are made up of different wavelengths interacting with cells

    So does that change the fact that Magenta has no wave length of its own?

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  14. exchemist Valued Senior Member

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    No. As previously explained, the colour magenta is produced by a mix of wavelengths from the red end of the spectrum and from the blue end, which stimulate both our red and blue receptors and thus creating the sensation in our brains of magenta.
     
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  15. el es Registered Senior Member

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    The best magenta is a mix of red and violet.

    The absolute best is to use two prisms in a shaft of sunlight. Tilt the prisms until the red of one mixes with the violet of the other.

    FANTASTIC!
     
  16. DaveC426913 Valued Senior Member

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    Is there ... a worst magenta?
    Is there a scale of magentas from best to worst?

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  17. el es Registered Senior Member

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    Yes Dave, there is a worst magenta, just add brown and it becomes the color of mud.

    Yes Dave, there is a scale, color grading like for gemstone amethyst, consisting of hue, tone, saturation, etc.
     
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  18. DaveC426913 Valued Senior Member

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    Ah yes. Rainbow Brown. Hiding in the spectrum between green and cyan.

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  19. exchemist Valued Senior Member

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    That’s fair. How does rosaniline compare with the spectral mix approach? Do you know?
    I found this colour wheel : https://i.pinimg.com/originals/48/bc/72/48bc72c32dfb9274c898d2ae94a5e1aa.png

    which includes a tone called “aniline” which could be it. It can’t mean actual aniline as that is colourless, so I guess it refers to an aniline dye. Magenta is shown as being a bit redder. Amethyst is also shown.

    P.S. in fact “aniline” on that colour wheel might instead refer to Perkin’s original aniline dye, which became known as mauveine, I think. Rosaniline seems to be a bit pinker, so indeed more magenta-like.
     
  20. Pinball1970 Valued Senior Member

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    I worked for Clayton Aniline for 10 years, dyes and chemicals. They were actually CIBA by the time I got there. Happy memories.
     
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  21. exchemist Valued Senior Member

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    Really. In what capacity?

    My first girlfriend’s dad was MD of their operation near Horsham. Back in the 1970s.
     
  22. Pinball1970 Valued Senior Member

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    They sold dyes and chemicals and the techs (us) provided formulations to apply them.
    So recipes and a dye profile to achieve a colour or an application to achieve an "effect"

    Our customers were the UK dye houses, sadly they have mainly moved abroad now.
    Or rather the clients that bought from those dye houses use producers abroad now.
     
  23. Pinball1970 Valued Senior Member

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    I still have the Environmental report from the Clayton site from 1983. I did not join till they moved to Macclesfield.
     

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