I don’t think the colors are faded. Here are 2 Gaines Files copies of Weird Fantasy 15 from the Heritage archive that shows a purple cover and a blue cover. If we assume there has not been any fading in these GF copies, I believe the difference is due to the slight variation in the mixing of the printing inks. Since comics were printed using a 4 color CMYK process (cyan, magenta, yellow & black), a slight variation in the ratio in one of the inks will make a visible difference in the co