Why the fading paint?

Why does the paint on some General Electric locomotives fade so much over time? Some of the Atchison Topeka & Santa Fe General Electric Warbonnets are fading down to a pink color http://www.railpictures.net/viewphoto.php?id=91906 while the E.M.D Warbonnets http://www.railpictures.net/viewphoto.php?id=95451 are not.
Here is a photo comparing the two Warbonnets. http://www.railpictures.net/viewphoto.php?id=111183 the GP60M looks a bit redder than the C40-8W even though the GP60M was built and painted about two years earlier. It is not just just ex. Atchison Topeka & Santa Fe locomotives either. Burlington Northern & Santa Fe and Conrail both have (had) similar problems. http://www.railpictures.net/viewphoto.php?id=74519 http://www.railpictures.net/viewphoto.php?id=71513
So, what is the reason for the General Electric painted locomotives fading faster then their E.M.D counter parts?
I know that that the E.M.D locomotives have a fading problem too, http://www.railpictures.net/viewphoto.php?id=101266 but it is not as bad as the G.Es

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Can you say "GE sued their paint supplier over these fading paintjobs "

This was a problem for both builders almost from the start, and many warbonnets were partially repainted under warranty.

Thank you for your information junction tower Ol' Loco Guy, and anyone else who wants to add something. I did not realize that General Electric sued the paint supplier!


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Many of Conrail's later C40-8W's (high 6100's and 6200's) also noticeably faded over time - some almost looked powder blue after a while.

JD

Here's an oddity though, most of the former Conrail units the CSX recieved have not faded. THis includes the handful of General Electrics and the bunches of EMDs the recieved during the merger.

Perfect examples would be CSX SD50 #8499 and
CSX SD70AC #779

The 8499 and the 779 really aren't good examples of non-faded Conrail power because the 8499 was repainted (it was not delivered in the "Conrail Quality" scheme), while the 779 is simply too new (it was among the last Conrail units delivered).

Stuart

Here is an example of faded CR paint on a C-40-8W coupled to another in good paint at Enola yard.