I've attached some more samples from a sheet-fed offset print (no replicates, n=1). Maybe it can shed some more light, figuring out what happens below 400nm. I haven't found any specs on the UV filter. I just assume it's filtering less than and equal to 400nm. Anyone? Oh, and here's a key for the measurement file: 1 Paper 2 C 100 3 M 100 4 Y 100 5 K 100 6 C 50 7 M 50 8 Y 50 9 K 50 Martin Weberg