Shade Variation Issues!!

[vmarda]

Guys need some help! I run pharma jobs on a 4 color Komori ls28 and have been experiencing a lot of shade variations lately while running the same job. Would really appreciate Ideas or assistance! sorry about the exclamation points but it just shows you how desperate I am :-)

Thanks in Advance!

[Greg_Firestone]

Can you provide more information? What do you mean by shade variations? Dot gain issues? Color issues? Is the color a CMYK build, Spot, etc.? Do you experience the issues on your proofers or just on press? Also are the variations from press run to press run or within an actual run?

Greg

[Cornishpastythighs]

Are you using tools to measure your process? If so what are they telling you, trap, dot gain, ink density variation.

[vmarda]

Hey by shade variation I mean color issues. It's a spot build and I experience it within an actual run.

I was advised to check the ph/conductivity of my fountain solution and am looking for other checkpoints.

[rich apollo]

Are you seeing inconsistency through a run? Are you seeing inconsistent results from different press runs - for example, are you replating a job and getting a different look from the previous run?

[Cornishpastythighs]

I would start by identifying what type of variation you might have. Is it dot variation(slur/double/excessive emulsification(fat dots), ink density variation, ink trap varitaion.
Go back to basics and check all your press settings
Rollers-stripes/settings/durometers/temperatures.
Fountain solution- pH/Conductivity, check this throughout the day, are you using plain Tap water or do you use filtered water(RO) if your raw water is changing it could affect your colour.
Dampening system- FS temperatures, Roller settings, Condition of chromes and metering rollers.
Blankets and packings- Check for correct squeeze, correctly torqued blankets,
Inking system- ink ductor issues, condition of inks keys and ink fountain. Try another ink series.
Is the issue happening to every unit or just one or two units
Things to be trying anyway.
Good Luck

[Prepper]

When we've had this sort of trouble it turned out to be trapping M to C, if someone could tell me what causes that to come and go during a run, that would be great. Changed from purple to bright blue and everything in between.

[rich apollo]

When we've had this sort of trouble it turned out to be trapping M to C, if someone could tell me what causes that to come and go during a run, that would be great. Changed from purple to bright blue and everything in between.

Sounds like an ink and water balance issue. Check the condition of the rollers in the magenta unit. Calcium build up, glazing, hard rollers, that kind of thing. Could also be a problem with the graining of the plates combined with the fountain solution you're using. I've fought that one before.

Crowned rollers can cause this kind of thing, too.