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Medical White shirts washed in blue makes them brighter

  1. Jun 30, 2011 #1
    Hey there,

    Since old times it's known that white shirts, tainted by blue, will look brighter, thus whiter. I heard that it has to do with bipolar cells (Wh, Y B and R G) responses. If we put them in 3D plane, then vector's module is longer if both Wh and Y B cells react as opposed to reaction of only Wh cell (Pythagorean theorem). But why exactly we have to use blue to get brighter shirts? Red colour would also make vector's module longer.
     
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  3. Jul 1, 2011 #2

    Ryan_m_b

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    Welcome to PF arbuzas. I'm afraid I cannot make sense of what you are asking at all, are you by any chance using an online translator?
     
  4. Jul 1, 2011 #3

    Evo

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    This doesn't sound like it answers your question arbuzas, but explains what bluing is. My mother used it in the laundry when I was young.

    This doesn't belong in medical, your question is along the lines of biology and chemistry. I'll decide where to move it later.

    http://boards.straightdope.com/sdmb/archive/index.php/t-113007.html
     
  5. Jul 1, 2011 #4

    turbo

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    Yep. Whites could become yellowed by staining from sweat, etc, and bleaching alone couldn't take that color cast away, so my mother used bluing when washing whites.
     
  6. Jul 2, 2011 #5

    marcus

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    Evo's straightdope link had a post from someone named "Squink"


    Squink 05-02-2002, 10:25 PM
    "people today think that if a product is going to whiten clothes, it is going to do so by removing dirt, not adding a dye."
    :p Tee hee... Actually these days we use fabric brighteners like 4-Methoxy-N-methyl-1,8-naphthalimide or 7-(2H-Napthol[1,2-d]triazol-2-yl)-3-phenylcoumarin which absorb ultraviolet light and emit bluish light. This makes the whites appear whiter and the colors appear brighter, regardless of whether the garment is actually clean.

    So people used to put some blue tint on Whites to cancel the yellow dinge.
    Now, if we believe Squink, they put on a fluorescent dye that absorbs UV and radiates blue light. Which would have a similar effect but a bit souped up perhaps. Formidable.
     
  7. Jul 2, 2011 #6
    I see that the most prevalent explanation is that in subtractive color wheel yellow and blue are in opposite ends. That means that they are complementary which in turn should mean that mixing them results in white color. For what I know that would be true in additive color mixing (if we were mixing illuminants). Because in subtractive color mixing yellow + blue = green.
    ryan m b: no, i'm not using online translator. It's just that I'm not used to using scientific terms in English.
    It's my fault I didn't put it clearly so I'll try again. I have psychophisics textbook in which is written that there are three types of bipolar cells in our eye: luminosity (White-Black) and opponent (Yellow-Blue; Red-green). Then eye receives information about color, these cells respond in varying proportions (depending on light's properties). So we could lay responses of these 3 cells in 3D plane. Perceived color is a vector, which is a result of summation of 3 vectors that indicate responses of 3 cells. It's written in this textbook, that perceived luminance depends on the length of this vector. And after this follows the question about this bluing thing (and unfortunately without answer). So I thought bluing had to do with responses of these cells. But I haven't found any source that would confirm this.
    Evo: thank you for the site and sorry I chose the wrong section
     
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