Ink Stains When Starting Run

[Seagull]

Hello all, I hope someone can shed some light on this for me. For about 3 or 4 months litho has been bringing me sheets, I am CTP, these start up sheets seem to have what I call stains or streaks of ink on them all over the place and they seem to think it is my plates (Agfa Lap-V), to get rid of them they just wash the plates down and all is fine after. This does not happen every job from what I am told so it's hard to think it's the plates in my view, has anyone had this experience ?

 

[RGPW17100]

What kind of press is the main problem? I have seen this on smaller duplicators and it was because of the way the press operator was cleaning the press. If during the cleaning process all the presswash was not removed this would happen on the first few runs. It never happened if the press was cleaned the following evening then the start up run the following day would be fine. I use a varn v120 mixed half with water and still follow up with a small amount of mixed fountain solution when cleaning the press and have never had this happen to me. It could be plate related but need to know what press it is being run on and if it is mainly when running process or happens mainly when running pantone inks.

 

[Seagull]

This happens with either 4 color process or spot color jobs on a 40" KBA offset.

 

[couriergraphics]

make sure your rinse gum unit in the plating line is operating correctly.

 

[nhprinter]

make sure your rinse gum unit in the plating line is operating correctly.

+1. It sounds like a gum issue.

 

[Seagull]

I assume you mean the gum issue is caused by my plate processor, Thanks in advance.

 

[nhprinter]

I assume you mean the gum issue is caused by my plate processor, Thanks in advance.

Correct. It may or not be the problem, but It's a good place to start.

 

[Cornishpastythighs]

Not sure if this helps but we had the same/similar problem as this and it turned out to be the lasers in our CTP needed to be calibrated, I guess after a time they slightly diminish in power and have to be checked, the suppliers Kodak/Heidelberg came in and run some test plates through the CTP then adjusted the power of the lasers(we have 3) Maybe a shot in the dark.

 

[Seagull]

Thanks all, I have my tech man in today, I will let you know his findings.