You are probably experiencing something like a bronzing effect but with dye ink. I have seen that effect before when using color and it varies by paper. I don't know what is happening but I suspect it either has something to do with the nature of the coating or the ink load limit of the paper. I have only seen something like this on high gloss type papers.
Swellable papers are coated with something like gelatin which if you touch it with a moist hand will instantly dissolve and feel tacky. When the print is wet it is still soft and tacky. The ink droplets dissolves into this coating and then swells. If you look at the print when just printed you can see ridges on high contrast lines. When the print is properly dried, it shrinks back down and becomes smooth again. I suspect that because the ink does not dive into the paper and bleed as much, color control and linearity is superior. On color photos, this can be seen in better resolution of various tones especially in the shadows. With this type paper, the Pro9000 finally stretches its legs and shows what it can do. At the same time, these papers allow the CMYK models to positively print at a level unimagined.
The only downside to these is that they are generally more costly, and water will destroy prints instantly.
This gel coating also locks in the dye and I suppose seals it for much longer life as well.
With microporous papers, the reactions of the ink paper and coating appear to be more complex. That is possibly why even when the base white is similar on different papers, the color tones can be very different even when using identical inks.
On a particular model of Glossy paper, I end up getting a selenium look when using this inkset. Which particular model, I don't know as I was just given some of unknown origin.
