Author Topic: Film Output Banding  (Read 3857 times)

Offline endhymns

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Film Output Banding
« on: January 31, 2020, 01:31:30 PM »
Hey y'all. I was hoping I might be able to bounce an issue off of the board and see if I'm missing anything. I occasionally have an issue pop up that is so sporadic it's nearly a non-issue, but I'm have difficulty tracing the issue back to the root and am open to any ideas.

About 90% of the tonal work that we print is pre-bitmapped as a stochastic dot and therefore, I don't always have the luxury of applying a curve to the output file. With this kind of work, I'm typically attempting to control gain with the droplet weight and walk a fine line between films that aren't completely blown out and too dark, but dense enough to hold my highlights as well.

So here's my issue... I run two T-Series printers, a 3270 and a 5270. Both are set up nearly identical to each other. For the last year or so, I've been running Ryonet Rite film with Freehand's DMax dye ink through the matte channel. I have the resolution in Accurip set to 720x1440 as 2880x1440 just lays down too much ink. With that said, I get some noticeable banding as the printhead makes is second pass back to the home position (see attached photo). This is obviously a non-issue with chunkier art, but on the rare occasion, these bands will burn in large tonal areas and pop up on press. I've generally been able to rectify this by backing down exposure times which leads me to believe that I'm dealing with some undercutting.

For what it's worth, I'm running a dual cure emulsion, all nozzles are printing clean and I've done a printhead alignment on both printers.  I've played with both the platen gap and the paper feed adjust without any noticeable improvement.

Any thoughts are appreciated!