Weird scumming on Heidelberg SM74

[Rabin]

Currently operating on Heidelberg sm74 and scum on magenta is eating my brain.
It's ok on small size but when a job is printing on full size that is 740mm paper, scumming appears on the operating side and from middle and below on the edge of paper. But ink is washed next to scum from top to bottom.
All the rubber rollers and form rollers are brand new except for Water form roller and Pan roller. Which I guess is a culprit right?.
What should i do replace water form roller and pan roller??

 

[Joe Burger]

hello, just let me know how much alcohol you add into fountain solution?
If the alcohol in the printing press is reduced, the properties of the dampening solution and thus the entire printing process
change significantly. The viscosity of the dampening solution decreases, while its surface tension increases. This significantly changes the dampening solution transport in the machine and makes the ink-water balance more unstable.

I guess you are loosing print-stability very often and fast after starting to print. What is the pH-value in the fountain solution actually showing?
At first glance, it may appear that the dampening rollers need to be replaced, but first of all, you need to check how good or bad the fountain solution is.(!) Did you have the oportunity to measure pH- and conductivity-value of the fresh water and fountain water?
What additive is in use?
How is process setting-up new mixing of fountain solution and how the printer is working?
What hardness (dH) the fresh water do show?
I am fairly certain that if we improve the fountain solution settings, it will not be necessary to replace the dampening rollers.

 

[Joe Burger]

Question: How do you obtain new rollers in your country? Which manufacturer/supplier is accessible to you? Should we attempt to obtain new dampening rollers here in Germany?
If you could send me photos of the dampening rollers, that would be helpful for a more in-depth analysis.

 

[Lukaa Lonca]

Felix Böttcher GmbH & Co. KG its much cheaper than Westland what new machine have.But we have were i come Slovenia very good companies for rollers

Best Luka