 :::*Renoir and the fading of carmine lake. I've got some inkjet prints from the 1980s on display that have remained relatively unfaded (the inks would fade within hours in direct sunlight). I think this is because the prints are pressed up against the glass, and oxygen can't get at them. Left a commission bid on that painting- the photos I took with my phone don't show the vibrancy of the yellows.   