As usual, lots of blatant misinformation is inevitable on these kinds of threads. C41 is a film process. I presume that chromogenic color prints made from color negatives, internegatives, or even scans are in mind, which are now the RA4 process. Real world testing is quite a different thing from marketing BS or rumor. Inkjet just haven't been around long enough to make broad generalities. But the bigger problem is that there are so many potential ways of doing these, and so many different inks involved, that what applies to one specific case might not apply to another. The same could be said about dye transfer in the past, or even true pigment prints (which inkjet is not). I hung early Cibachromes in indirect mountain sunlight for over thirty years without noticeable fading. Direct sunlight is a different story. Chromogenic prints have been around in some form or another long enough to give us a general ideal how they will fare, and how certain products probably have notably improved in terms of display longevity. But by how much I have no idea. I've got a number of big Crystal Archive prints in environments that will tell the story eventually; but I might not be around personally to witness the result. Gradual yellowing due to residual couplers is often the limiting factor rather than just fading per se. Fuji is rather mum on this point except to provide an extrapolated estimate of yellowing vs fading, and to cryptically suggest in their literature that the gloss polyester medium is more immune to yellowing than the RC paper base. But don't take Wilhelm as the Bible. He deserves credit for renewing interest in this whole subject, but his methodology was fraught with all kinds of preconceptions about the utility of accelerated-aging "torture" tests, which do not always accurately predict the many variables present in the real world. Others since him have helped patch some of the holes in his methodology. It is true that casual processing options through
mini-labs and drugstores often cut corners for sake of speed, or otherwise used so-so chemicals and minimal washing, so ended up with especially fugitive prints.
