Printer manufacturers like to say that dye-based ink give smoother, more vivid colours, while pigment-based inks are more fade-resistant. They also like to tell you - well, tell us journos, mainly - that it's very important to use the right paper with these different ink types. The argument goes like this.
Dyes use very small particles of colourant, dissolved in liquid. They are easy for ultraviolet rays to damage, one of the main mechanisms of light fading in prints. To protect the dyes, it's important they can soak into the surface of the paper. With pigments, which use far larger particles of colourant held in suspension, ultraviolet rays cause much less degradation and it's better if the pigments sit on the surface of the paper, without soaking in.
The inks used in this test are a mixture of the two types. Canon's Chromalife inks use dye for the colours, but pigment for black. Epson and HP stick to dye inks for both, while Lexmark uses black and colour pigments. You would therefore think that paper designed for dye-based ink would do much better in the Epson and HP printers, while those happier with pigment-based ink would give the best results in Canon and Lexmark's machines.
In fact, though, it appears to make very little difference. Canon's mixed ink approach does very well on all the papers. The Ilford paper, designed to work with ‘all brands', is just as happy with Lexmark's pigments as it is with HP's dyes. In the fade resistance stakes, the compromise coating of this third-party papermaker seems to be doing an excellent job.
There is one anomaly, though, which may be down to a problem with a paper's coating…