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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.
wild guessbecause the ink is packed so tightly that light cannot penetrate it? Maybe the pen casing has something to do with it../wild guessit's a good question that needs someone with knowledge to answer it..
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!
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).
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.
Quote from: rosalind dna on 26/08/2008 12:11:21Red 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...[attachment=4306]http://en.wikipedia.org/wiki/Sunlight#Composition_of_sunlight
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/PhthalocyanineOn 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.
This is great RD...I can either await the delivery of my star or go grab a torch end empirically do this myself.