Dot gain?

I need to get better control on dot gain.
We guess to much...

Is there a good read on avg. dot gain for sheetfed offset?

What are most peoples avg. dot gain??

How I was show was to get film into cal. 30 reads 30, etc.
Then for dot gain or prod. manager jacks the exp up from 7 to 9. This works most of the time.
But, a lot of the time stuff looks light. Were not a true 4cp shop. We run on 2 color press w 2 passes.

I know we can setup profiles, trans curves, etc. This is what I want to do....I'm sick of guessing.
We need a profile for gloss and offset. I dont want to put trans curves on pics etc. I want a profile setup at the rip so I know when I'm in cal. the rip will handle dot gain. There is a spot in the rip for that.
Just want to see what other do before I did on my own.
Were always Soooo busy, we never have time to do shit.
Please Help!
 

meddington

Well-known member
Re: Dot gain?

I would recommend taking a look a the G7 methodology, which is currently adopted by Gracol and SWOP (and soon possibly FIRST for Flexo) which allows for a common tonal respose and gray balance from differing print processes using differeing consumables. Read the G7 "How To" guide and familirize yourself with the concept. Basically you would compensate your Rip output to match the targets for print density or gray balance. Implementation can be done by manual calculation, or by software such as PefX or Idealink Curve.
 

Gerhard

Active member
Re: Dot gain?

Dot gain control is not just only building a curve in the RIP. This is what you do after controlling the variables affecting dot gain. It is hard work and it needs close cooperation between prepress and press but after all you will like the result.

The following variables have been found to affect dot gain:
Ink: Tack and Viscosity, Ink / Water Balance, Pigment Strength, Temperature, Ink Film Thickness (Print Density)
Paper: Brightness, Whiteness, and Opacity, Porosity / Holdout, Smoothness, Web Tension
Fountain Solution: pH / Conductivity, Hardness of Incoming Water, Type of Dampening System, Formulation
Blanket: Compressibility, Age, Tension, Surface Characteristics
Plate Exposure: Processing, Reactions (Age, Light, Chemicals)
Tension: Rollers Diameter, Settings, Glazing
Speed: Low / High
Packing: Over / Under

It is important to realize that the ink film thickness will have a dramatic affect on Dot Gain. Therefore, it is critical to monitor and control ink the density during a run so that the dot gain is consistent throughout the run.
The Dot Gain should be rechecked after any variable is changed in the printing process but in general latest every six month
 

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