Naked Science Forum
General Science => General Science => Topic started by: neilep on 25/08/2008 02:56:34
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Dear All,
As a sheepy, I am of course a prolific writer...and pens (apart from being confined in them ) are my all time favourite writing tool that contains ink !!...well..I did try writing with a squid once but it was well sloppy !!
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My Book "The Ewe Inside Of You" and my film "Sheepless In Seattle" and my Clark Gable Line " Frankly My Dear, I don't give a Ram" were written by good old me !!
...But will ewe take a look at these implements of writing aid ?
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Why does the ink in all the pens look the same colour ?..They are not mistakes, the red is red , the blue is blue etc etc.....
Why's that then ?...whajafink ?
Thanks
neil
Pen Pusher
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wild guess
because the ink is packed so tightly that light cannot penetrate it? Maybe the pen casing has something to do with it..
/wild guess
it's a good question that needs someone with knowledge to answer it..
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The colour of the ink line on paper is seen because light goes through the ink, is reflected by the white paper and comes out again. Red ink absorbs light with other wavelengths and lets quite a lot of red light through (etc, for other colours).
The ink in the tube is so thick that it even absorbs the red as well so it looks black. If you are prepared to get in a mess, squeeze some ink out onto paper and see the difference between a thick layer and a thin layer, Choose a cheap pen, though!
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If you backlit the pens with a strong enough light, the colour of the inks in the refills would become apparent.
(If you attempt to take a photo exposing for the ink in the refill, the rest of the image will be grossly overexposed).
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Red inks fade faster than the Blue or Black ones as far as I am aware. I don't have any scientific reason for that.
Also Yellows too and specially if they are near the Sunshine say coming through your office or home's windows.
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Red inks fade faster than the Blue or Black ones as far as I am aware.
I don't have any scientific reason for that.
I've often seen posters shop windows where blue is the last colour to fade,
i.e. sunlight has caused the multi-coloured poster to become a faded monochrome blue.
I did think that this was due to there being less blue in sunlight than the other colours...
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http://en.wikipedia.org/wiki/Sunlight#Composition_of_sunlight
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Cool imformation.. That means my red ink I love so well will not be saved forever... OOOOOH NOOOOOOO, LOL My words will fade and die away.... I'm sad!
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Blue bits of posters are often the last to fade because there's a cheap easy blue pigment called copper phthalocyanine which is remarkably stable.
http://en.wikipedia.org/wiki/Phthalocyanine
On the other hand you might reasonably expect yellow dyes to fade quickly- they have to absorb blue/ violet light and that light has the highest energy (per photon) of any visible light. It's more likely to have enough energy to damage the dye molecule. At the other end of the scale, greens should be stable (and if that were a political comment, Green would have a capital letter).
Anyway, to get back to the original question. In theory an ideal ink would only absorb the colours you want it to. Even in a thick layer of a concentrated dye blue would still look blue. However, in the real world the absorption of light happens at all wavelengths (though the absorption is much stronger at some wavelengths than others). If the layer of ink is thin, as in writing, only the absorption of the "right colour" light shows up. With a thick layer all the light is absorbed so they ink looks black.
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wild guess
because the ink is packed so tightly that light cannot penetrate it? Maybe the pen casing has something to do with it..
/wild guess
it's a good question that needs someone with knowledge to answer it..
I agree, someone with more knowledge (but ewe're klevur too )..I have to scroll down and read the other posts so hopefully somewhere south of your post is an answer to bring me inky joy !...though, I like your idea of the density of the ink. The pen casing is clear plastic !
Thank ewe JnA
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The colour of the ink line on paper is seen because light goes through the ink, is reflected by the white paper and comes out again. Red ink absorbs light with other wavelengths and lets quite a lot of red light through (etc, for other colours).
The ink in the tube is so thick that it even absorbs the red as well so it looks black. If you are prepared to get in a mess, squeeze some ink out onto paper and see the difference between a thick layer and a thin layer, Choose a cheap pen, though!
Thank ewe very much sophiecentaur Jna is correct then.
Yes, yes, I am prepared to get messy and have expertise in obtaining cheap pens. I nick them all from my neighbour...oh..and ASDA do a pack of ten for 31p....31p !!...amazing !
Thank ewe so much for your great explanation.
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If you backlit the pens with a strong enough light, the colour of the inks in the refills would become apparent.
(If you attempt to take a photo exposing for the ink in the refill, the rest of the image will be grossly overexposed).
This is great RD...I can either await the delivery of my star or go grab a torch end empirically do this myself. Empiricising (new word) is one of my favourite things.
Thank ewe again.
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Red inks fade faster than the Blue or Black ones as far as I am aware. I don't have any scientific reason for that.
Also Yellows too and specially if they are near the Sunshine say coming through your office or home's windows.
Really ?..I never knew that. Thanks for the info Rosalind
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Red inks fade faster than the Blue or Black ones as far as I am aware.
I don't have any scientific reason for that.
I've often seen posters shop windows where blue is the last colour to fade,
i.e. sunlight has caused the multi-coloured poster to become a faded monochrome blue.
I did think that this was due to there being less blue in sunlight than the other colours...
[ Invalid Attachment ]
http://en.wikipedia.org/wiki/Sunlight#Composition_of_sunlight
Great info yet again from the RD
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Blue bits of posters are often the last to fade because there's a cheap easy blue pigment called copper phthalocyanine which is remarkably stable.
http://en.wikipedia.org/wiki/Phthalocyanine
On the other hand you might reasonably expect yellow dyes to fade quickly- they have to absorb blue/ violet light and that light has the highest energy (per photon) of any visible light. It's more likely to have enough energy to damage the dye molecule. At the other end of the scale, greens should be stable (and if that were a political comment, Green would have a capital letter).
Anyway, to get back to the original question. In theory an ideal ink would only absorb the colours you want it to. Even in a thick layer of a concentrated dye blue would still look blue. However, in the real world the absorption of light happens at all wavelengths (though the absorption is much stronger at some wavelengths than others). If the layer of ink is thin, as in writing, only the absorption of the "right colour" light shows up. With a thick layer all the light is absorbed so they ink looks black.
Quality Info yet again. Thank ewe Bored Chemist
I do appreciate your explanation here.
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I want to thank everybody for their wonderful responses to this post. I was beginning to wonder if an answer was readily available and I am in debt to ewe all for the time ewe have taken to elucidate in a way that even i can understand.
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This is great RD...I can either await the delivery of my star or go grab a torch end empirically do this myself.
Star not required: putting the pen on a camera flash should produce sufficiently bright backight.
You'll need an off-camera (separate) flash gun with sync lead (or slave trigger), e.g. (http://www.ckcpower.com/Merchant/merchant.mv?Screen=PROD&Store_Code=digital&Product_Code=CobraSlave&Category_Code=SlaveFlash)
BTW Bored Chemist is correct about the persistent blue dye on the posters.
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Mabe cos they are