Sharpness loss in inkjet prints

I would like to ask if anyone printing inkjets has noticed a dulling of sharpness and contrast in their inkjet prints with time. A friend of mine showed me two inkjet prints of an identical image. One was printed a day of so before, the other two one was printed two weeks before. The older image was noticably less sharp and contrasty. Colours were similar. Both images were printed on glossy paper. I have also noticed a similar effect with my own inkjet prints. Initially I'm very happy with the sharpness of the resulting print that comes out of the printer. A day or two later I'm still happy, but if I look at the the print a week or two later the print seems softer.
Digital prints I've had made at the lab on real photo paper from my 4x5 Velvia scans do not exhibit this problem, they still look sharp whenever I look at them. I'm fairly certain I'm not imagining this effect. Is it just me? or have others experienced this ?

Specifically what brand inks and papers are you using Robert?

I use an Epson 1280 printer, and I haven't noticed anything like that.

I don't see this effect on prints from my epson 9600, using Ultrachrome inks on Epson Premium Luster paper, using the Epson driver to drive the printer from Windows XP.

It would be interesting to know what printer, inks, and paper you're using, as well as what software (a third party rip?) to drive the printer.

I can imagine situations where you're simply laying down too much ink, and it spreads over time, killing the sharpness. Or even some problem with the paper.

But without knowing more about what you're using, we're all just speculating.

I've had prints on Ilford Smooth Pearl using MIS dye ink on a 1280 show noticable bleeding after several months. But that was a few years ago, and they may have changed the paper by now.

I'm using an Epson 830 printer (Epsons entry level photo quality printer) with epson ink and epson premium glossy paper and an NCR heavy duty glossy paper. My friend who initially showed me this effect, was printing on an Epson 1290 with standard epson inks and premium glossy paper.

Sounds like dot gain to me. That would be consistant with the dye inks that glossy paper implies. If you are using dye inks, you should be using a paper (and an ICC profile) designed for the duty. I'm thinking along the lines of Lyson's Darkroom Range Gloss, or a similar paper. The profile is important because it tells the printer how much ink to put on the paper. Excessive ink laydown on an RC paper can cause this very problem.

A possible solution, without changing anything else, would be to dry the prints with a hair dryer. The hot moving air will evaporate the ink carrier from the paper (hard to do with "air drying" RC papers because the carrier can't evaportate out the back of the print). This in turn should bring the interaction of the ink and paper to an end quickly. Think of it as a stop bath for an inkjet print ;-)

It's a multifaceted problem, with multiple possible solutions. Clearly, YMMV.