cloudy prints

[Slammer]

Just been looking at some print samples, in the gradients I see a 'mottled' effect, almost like they have been done with Photoshops 'difference clouds' I have the sneaking suspision that it is due to someting with the plate (ohkaflex digital) surface tentions (dyne?) anybody got an idea.

 

[richprint]

Can you post a picture? Are you printing CMYK or spots and is it only in the highlights?

 

[Slammer]

It is most visible in a gradient in all 4C's, the engraving and the plates check out ok, however only the engraving is under my control all other processes are in other companies, UV and washout the other end of Antwerp and the printing in Holland

 

[FlexoGrunt]

Looks like LPI too high for material? Just a guess.

 

[Slammer]

Don't know about that, 150lpi at 2540 dpi (or 2032 ppi in reality land) round dot. Anyway next test shot is underway using a merged bump-up and TVI curve (BRRRR! Don't ask) together with a device-link ICC profile.
The general idea is to have a identical print from Flexo and Digtal to show off at DRUPA.

 

[FlexoGrunt]

Don't know about that, 150lpi at 2540 dpi (or 2032 ppi in reality land) round dot. Anyway next test shot is underway using a merged bump-up and TVI curve (BRRRR! Don't ask) together with a device-link ICC profile.
The general idea is to have a identical print from Flexo and Digtal to show off at DRUPA.

What I meant was some of the newer (and value oriented) materials have a very weak coating (see the new KK from Fasson. It's horrid). These crummy coatings make for a very uneven surface.

Anyhow, it was just my thought from what I've seen.

 

[Slammer]

Ah! Now I am with you and you could be correct.
I have now just found out that the substrate used in the test was different in the Digital press to the one used in the Flexo Press.
I was able to prove it by measuring the difference in the white of the paper with a spectometer also you can see the 'clouds' under UV light on the substrate.
Still the buggers in charge have set up the next shot using the exact same stuff and methods and I predict another disaster.

 

[FlexoGrunt]

Yeah, we just tested a new face stock that we (industry) are being forced to and it's horrible. We experienced the same "cloudy" 4cp printing you did on the new stock whereas the old stock with the same plates printed it perfectly.


So many variables.