Let me start by saying that I do only have a basic understanding of how e ink works. In an attempt to add to a technical understanding of the sun fade issue I submit the following. The xerographic principal is based on the fact that a sufficiently bright light will dissipate a static charge on a surface. This could be a factor in the problem that we are seeing. As the charge on the top electrode becomes less positive the black pigment is poorly attracted to the top surface resulting is poor rendering of black text.
Pardon me if this has been posted previously. I am waiting for the rain to stop to test my new PRS-600. I have my fingers crossed as I tip4e t8hi-s.
Cheers,
kev