Till yesterday for my DNs I've used some UV blocking-colors recommended by others in their posts on different sites. Yesterday I have decided to see myself what the best UV b-c is for my printers. I printed Mr. Peter Mrhars' HSB grid on a sheet of Pictorico with an Epson SureColor SC-P600 printer and made a VDB print of it with a 3min exposure time on a sheet of Bergger COT32. The result was not satisfying: a too short exposure to clearly see the best UV b-c. I did it again with anothe sheet of Bergger and with a 5min. exposure - again too short. This time I re-aligned the negative and gave it 10 min more UV. exposure - not enough again! I re-aligned the DN again and gave it another 10 min of exposure. This time it was a bit over-exposed (25 min exposure!), exactly how I wanted, and the best UV b-c could be clearly seen. It was quite close to what I use for VDB. Today, watching the 2 prints, I realized that I can't understand why that color is considered the best UV b-c. It is, obviously, the "most blocking" UV color, but why should it be "the best"? If looking at the column of grays (well, browns..) beneath it it's clear that it will need a quite "strong" correction curve when used for a DN (quite distanced from diagonale). On the other hand other colors would need a more close to diagonal correction curve while giving a good white and a deep black (brown..), too, with the 3 min exposure time (or a bit more) instead of 25 min (or a bit less). Why is the "most blocking" color considered the best choice and not the one that needs the less corrections (while both give similar max. black and max. white, but at different exposure times)? It doesn't seam logical to me. Am I missing something? Look at the 2 prints how different the 2 colors are.