Tests for yellowing of colors

Just a pointer today... I discovered this interesting web page where somebody tested paints for yellowing over a 5 year period. I haven't read all the notes yet, but it definitely sounds interesting - just the kind of stuff I'd do. Well, actually I have done something like that for printing inks and for my acrylics but I waited only a few months and left the samples out in bright sunlight, partially covered with multiple layers of aluminum foil. My results were that over the period I tested the paints barely changed at all. And that was in brightest sunlight in the California summer. So, really, modern paints are quite colorfast.

Anyway, here is the pointer to the site I found about yellowing of paints. What I miss on this site is a comparison of "after drying for 5 years vs. freshly painted". How else can you really compare when you don't see the two color samples next to each other in the same photo?! But the notes are still interesting.