Roland Deltamatic damping unit

[cementary]

Got a question about damping system: press operator got option called somewhat "inner delta"
If this option is on it makes a connection between ink rollers and damp rollers (see picture)


would there be difference in dot gain with this option on or off?

 

[Dan Roll]

It is a long way from the water form roller to the ink form roller across the surface of the two rider rollers, the path from the water form roller to the inker is much shorter across the plate and most of the water on the form roller takes this path. If you think of the plate cylinder as a water roller (a big one with a gap in it) all dampeners are 'integrated' when ever they are on. The exact purpose of the two rider rollers other than washing the water form roller along with the ink rollers escapes me.

 

[cementary]

...and most of the water on the form roller takes this path

I would agree with this, but pressman told me (actually he shown) that when "inner delta" option is on he had to increase % of water in ink/water balance to prevent scumming. Plus water form roller rotates faster than plate cylinder with delta (outer) on

 

[aqazi81]

I'm not familiar with the rolandmatic but I used to run integrated for heavy coverage jobs and disengage the bridge roller on lower coverage and metallic inks as it helps in preventing too much water getting into the ink.
Delta effect is for hickey picking but it can reduce the life of the dampening form roller and printing plate. Delta effect also helps in ghosting issues.

 

[Dan Roll]

The Delta effect ensures the water form roller and ink form roller are traveling at different speeds, so that connecting them with surface driven rollers means something is scraping somewhere.....

 

[Lukew]

99% of the time I always ran segregated, the 1% of running integrated would be if a certain PMS colour was giving issues.
From testing with CMYK I found integrated would achieve a quicker ink/water balance but generally had to run higher damp % levels to prevent scumming and also then higher ink feed levels.
The downsides were altered dot shape, slower drying etc.

 

[cementary]

The downsides were altered dot shape, slower drying etc.

Could you please detail your answer with the etc. part?

Just to make things clear:

1 - is "Delta effect" itself with different speed of roller
2 - is what called "integrated"

Let's get away from "dot gain" definition and head somewhere around TVI.
According to Gordo more water in ink – there will be problems, especially not fully controlled water as with "integrated" on.
I think that "integrated" option leads ink to emulsification, 'cause sometimes we see somth like "picture framing"

 

[aqazi81]

Emulsification is part of the offset process. but too much emulsification leads to problems.
You pointed out right in the pic, 1 is delta effect and 2 is integrated.