My comment was more about the Canon inkset typically touted as being better than Epson inks in longevity, so even on tests on the same papers types many claim the Canon inks are better. You certainly would know better than I whether there is any substantiation to this.
Rank ordering the OEM pigment ink sets for average overall lightfastness arguably puts HP Vivera pigments on top, Canon Lucia pigments 2nd, and Epson Ultrachrome varieties third (K3,K3VM, and HDR share a limiting yellow ink). However, let me be clear about this: there is considerable overlap in print durability when one factors in specific printer/ink/media combinations. While dye-based inks are highly sensitive to media chemistry, pigmented inks are less sensitive, but they are not immune. Epson Ultrachrome ink on well matched media will outperform Canon Inks or HP inks if media choice is not optimal for the Canon or HP ink. If it were not so, we'd only have to test each pigmented ink set on one or two media types, and we'd have the issue well documented!
Of course, this leads things completely off topic to the frequent discussion as to whether a print rated at 100+ years has any chance at actually surviving that long. I"m of the school that too many get hung up on longevity of the print failing to understand that just because a print might last 100 years, it's chances of that have little to do with the print and more to do with becoming famous, collected by significant museums who will preserve your work, or just plain luck ... in other words little chance of it happening for most.
Museums and archives rarely get the chance to acquire prints when they are relatively new, so prints that end up there did somehow survive the more widely varying real world for many years, sometimes decades. Yes, we are indeed getting OT, but to respond to the validity or lack thereof for 100+ year ratings.... even cheap litho inks on newsprint paper can survive in reasonable condition for 100+ years. We have many examples in libraries and archives that attest to this fact. In other words, longevity ratings are a grossly oversimplified marketing construct. The discussion in our profession needs to be switched from "longevity" to one about print "durability" instead.
Manufacturers and printmakers can only influence the durability of a print process, i.e., the ability of the print to resist change upon exposure to degradation factors like light, heat, humidity, ozone, etc. Print longevity is largely within the purview of the print collector/owner. In some sense, light is a very special case. "Average" light levels can vary by orders of magnitude even within one's own home environment, and the subsequent fading is essentially proportional to the intensity of the illumination. Hence, one can move a print a few feet over on the wall and double or halve effective rates of degradation without even realizing it. Under this very common circumstance the 100 year prediction for "noticeable fade" becomes 50 or 200 years depending on which way the average light level shifted. Put the same print on a sun porch or use it for commercial display purposes in a front window, and the 100 year rating may be small consolation as the print fades in just a year or two. All other things being equal, manufacturers and printmakers that strive for more durable prints provide the print owners with more latitude to safely display the prints under a broader variety of real world conditions.
cheers,
Mark
http://www.aardenburg-imaging.com
