Halftone Print Line Question

[steve B]

Originally Posted by ls7plus

Wow, Steve, I think you solved it! Makes complete sense! Your resourcefulness is incredible. Let's see if I can attach the image I was referring to from PSA (old school that I am, I've never done this before).Attachment 415668 You have to look a bit harder to see the higher line. I'm thinking that this was a limited event as to time and number of cards affected--is that consistent with your thinking?

With high regard,

Larry

Thanks Larry,

Drag marks can be transient. The guides can be adjusted, and sometimes it's a matter of a roller skidding on too much ink.
The presses at the place I worked were a little more modern, and the guides pretty much only dragged if the outfeed stack was too high. (and the pressmen caught it and those sheets got tossed. )

Those lines are interesting ones. The other example I found (Didn't look all that hard) only has one line, and a very slight line in a different spot. That would point to a transient event instead of a few other options.

drags usually have a lot of disturbed ink at the edges of them, and these don't. They also usually cross borders and again these don't.
The other options would be damage to the plate, or damage to the negative.
Plate damage looks different depending on the process.
On Offset lithography, it's usually a colored line where the scratch is.
On typography, it can be a white line like we see here.
But plate damage on either is very consistent, and affects every sheet after the damage the same way.

Since there aren't many with the marks, and the marks are uncolored lines either they were typographed, and the damage happened very late, or the negative was damaged before a new plate was made.
With two different ones, neither of those seems likely.

I suspect the culprit is the outfeed belts you can see in the video. The sheet probably touched just where the belts went around the pulleys, and only very briefly. I suspect that happened up on the press end, but explaining why is messy enough I'd have to draw a couple sketches.