Sonora Xtra plate question

[scotts]

We just started to notice some striations in the image of our Sonora XTRA plates that show up on the print. You have to look under a loop to see them, but we don't remember seeing them before.

And I'll admit, it is a bit hard to see under the loop, but the printed piece does show the striations, if there is a big enough single color solid. Albeit hard to see with the naked eye, very easy to see under a loop. Still should be acceptable, but need to look into the issue.

First question is, has anyone else seen this before? And how did you go about mitigating the issue?

Secondly, could we change the intensity of the laser of our Magnus 800 to overcome the issue?

Plate - color bar - under loop

Print - color bar - under loop

 

[maxon]

Have you cleaned the drum pressure roller and does is rotate freely ?

 

[scotts]

Our Magnus does not have a pressure roller for the drum. We also contacted our vendor, and they did say it was graining of the plates, which is normal. But he will look into the lot number and see if manufacturing was within spec.

 

[Asures]

Our Magnus does not have a pressure roller for the drum. We also contacted our vendor, and they did say it was graining of the plates, which is normal. But he will look into the lot number and see if manufacturing was within spec.

I have observed this issue with color bars on this specific plate before.

As a technical starting point, I recommend pulling some dry solids (individual colors) to determine if the issue stems from the plate or the blanket. In my experience, this is most common in the Black ink, as it is the least transparent of the process colors.

Depending on your press, this can become a significant issue if it is indeed the plate; the scanner may attempt to auto-correct densities to compensate for the lines in the color bar. I have specifically seen this occur with Komori GL and KBA presses.

To help me provide better support, could you please provide some details regarding your setup? Specifically:

- What press are you using?
- Are you using UV or conventional ink?
- What is the roller material (Conventional, Hybrid, or EPDM)?

Happy to help with some realistic field support.

 

[SteveSuffRIT]

Here is a simple test to isolate the plate from press.
Take a new plate, on a flat surface, ink it up by hand.
Use a wet sponge to dampen, then a hand brayer roller to ink up, but do it horizontal/lateral across, not vertical around the plate.
Visually inspect for any lines.
If no lines, then its press.
If there are lines, it's CtP or Plate.

 

[scotts]

Doing some more digging on our part, we have found out that the palette of plates' expiration date is July 2026. And talking with our plate guy, he said that he can see, is a side effect of that. It is not too bad at the moment, and the print is still sellable. We have another palette of plates on site that are good until Fed 2027. So we will switch if it becomes an issue.