Most of my images are very dark, so I don’t usually see problems in printing negatives as the negatives have very little black. Now, printing some lighter image negatives for a friend, I see the same problem he had. Black areas on the negatives how faint horizontal lines approx. 1.5 mm apart. We were trying to print negatives for Carbon Transfer and for salted paper. Cyanotype negs are less affected, though the lines will show up if a black border is printed on the negative. He has a 4900 and I a 3800. Both of us use the requisite Pictorico Ultra Premium OHP. Printing a straight (non-DN) image on Epson UPPM shows no lines in blacks on my printer.
Regarding nozzle checks, mine was fine both before and after I printed the negative. Power cleanings have made no difference.
I just printed with the exact same settings, (a DN Carbon printed through Manual Rear) but printed using Epson UPPM Paper instead of Pictorio. Gorgeous Blacks–no lines, even looking with a loupe.
Any advice? I was about ready to throw up my hands and buy a second p800 for Piezography inks but I just proved, I think, that the printer is very capable of responding to the driver when printing black ink.
Looking forward to hearing back from anyone, as I am eager to proceed with making more negatives.