Need help troubleshooting an ink problem offset web press

[Pkrfan]

Let me first apologize for the novel you're about to read, I wanted to make sure I gave as much info as possible.
Ive been having trouble with some ink and I can't seem to figure out the root cause.

Running a custom color blue which is 95% 280 blue with some violet and black added to it. Currently buying this custom color from 2 different vendors (Superior Ink, Press Color Ink). The Press color formula runs great with no problems at all. However, I have trouble getting the Superior formula to run for any longer than about an hour before I run into trouble.

What happens with the Superior formula is where the outside edges of the blanket touch the plate, the plate will start to take on ink which then transfers back onto the blanket and onto the web. Also, I start to notice a slight gap line across the entire web. The plate seems to have a nice even sheen of water on it when press is running so I don't understand what the plate is taking in in non-image area. If I wash the plate and out in the other vendors ink, problem goes away and press runs great. Any ideas on what could be causing this would be great.

I hate to put the blame on the ink but I'm not sure what else would be causing this. I've checked all roller settings/stripes which are all in spec. Plate to blanket and blanket to impression settings are good. Roller durometer are within spec.

Currently running a Didde Colortech web press with integrated water system. Using Varn Supreme 8168 one step fountain solution mixing 3-4 oz. per gallon of water. Using Varn Fountain Pure filters and the tank gets cleaned/flushed once a week.

I've tried adding up to 25% body gum varnish to the ink but that didn't seem to help. Adding alcohol to fountain solution is out of the question. I realize the etch is one step, but would adding a few more oz of Gum Arabic help at all? And suggestions would be appreciated.

 

[dabob]

This may be a dumb answer but why do you keep trying to run an ink that doesn't work when you have one that does? In our shop we would just buy the press color ink and forget about the Superior Ink . .. remember if it isn't broke - don't fix it!

 

[Cornishpastythighs]

Dabob says it all, if the other ink works use it and then you will have time to focus on other things.

 

[Pkrfan]

I agree on running what works as I can honestly say I don't enjoy fighting the press trying to get something to work. The thing is, another press in our shop usually can run this Superior Ink without much trouble. The other press is a '60s Stevens press with a conventional dampening system. There have been a few times where we're out of one vendors ink or the other and am forced to run the Superior Ink. In upper level managements mind, if one press hasn't much trouble and the other press has issues with the ink, then it must be a press problem. I just want to know if there something I missed or something else I can try to make it work.

 

[dabob]

The biggest difference I see is the dampening systems - which in my opinion is huge - its quite possible that while one of the inks can run on both presses its also possible that the integrated system may be more sensitive to any "short comings" in the ink that wont run . . . my 2 cents worth - its worth what you paid for it. If it were us the ink guy would be in here trying to figure it out.

 

[Mark Flanders]

It's perfectly reasonable to state that a certain ink doesn't work well on a particular press/dampening system. Based on what you've outlined, I'd say that is what is happening here. Alot goes into the chemistry of inks and maybe Superior needs a sample of the other guys to figure out what they've done wrong. Meanwhile, stick with what works.

 

[Cold]

By chance, do you run a heavier ink film with the Superior Ink to obtain color? In other words, Is there a noticeable strenght difference between the Press Color and Superior product?