haze on sheet edges

[Bill Rothwell]

while running my 4 color heidelberg perfector(black over black in units 2-3) i am getting a haze or scum on each edge of the sheets on both sides of sheets. I have repeatedly resett the rollers on both units and replaced both metering rollers but still have the same problem. it seems o.k. when I first start running,but shortly after, i begin to have this problem. I can kind of get around the problem by pushing water(and I mean alot of water by raising speeds to 70 - 75) to get it to clear. But it is not right. If I lower the water speed I don't get the normal dry-up, I get this haze or scum look. Anyone have any sugestions on what to try? I was thinking toward problems with ink or fountain solution also but I have been using both for over 5 yrs. without any problems. Thanks for any opinions or info., Bill

 

[nhprinter]

Hi Bill,

Your description of a "haze" makes me think that it might be ink contamination. Either oil from bad oscillator seals or maybe your wash up solution isn't coming total out of the press. Maybe if you give all the rollers a look after a wash up you might find something.

Good luck,
Dave

 

[Frank Rieder]

Bill,
This occurs in both units? 2 & 3. and only on the gear and op. side, or does it smear all
across the sheet?

I would check the fountain solution, ink and paper, doing the same thing in
two units doesn't sound like a mechanical problem.
Don't squeeze the meter roller too hard against the chrome, just enough to cut the
water film.

 

[Guest]

Have you tried a different batch/box of plates? Possibly weak plate developer or bad coating on plates?

 

[Bill Rothwell]

thankyou for everyones input,
Yes it is happening in both units and it does it up both op. and gear side edges of the sheets. I doesn't matter what size sheet we run, 40", 38", 35", it will show up both edges soon after running. Again, I can overcome most of it by raising the water extremley high, but thats not the right way to run a press. We just run perfecting, black type over black type primarily on this press. I have lightened up my metering settings till they just bearly clear from flood and still the same problem. I have had all the rollors out of both units, cleaned them and resett and installed new a metering roller in both units. i agree it seems to me that it points to ink or fountain solution, but I am hesitant because we have been running this ink/solution for 5plus years withou any problems. That being said, this problem showed up about 4 -5 weeks ago, all the sudden. I have tried differnt inks and still get the same problem. maybe the next step is to try a differnt fountain solution.....what do you guys think? none of our other presses have this problem. thanks again for everyones thoughts, Bill

 

[Bill Rothwell]

Erik,
No I haven't tried the plates, however, we don't have this problem on any other press. and we all us the same plates. thanks, bill

 

[Frank Rieder]

Bill,
When you say you raise the water to 75%, do you have too much water on the plate?
Or is it still dry?

Try this, reduce the press speed when the haze starts, if it gets worse, increase the
speed and see what it does.
This could point towards an issue with the electronic water/speed control.

 

[rapid3]

This is an alcolor system? If so, then check the settings of the chrome roller.
Try adding 1/4 to 1/2 turn on both sides & see if there are any changes.

 

[Bill Rothwell]

Frank,
the plate seems not to be to wet and I am not emolsifying on the rollers either running the metering speeds at 75% and up. This is why I was thinking it could be the fountain solution? does that make sence to you? I will try your suggestion of changing press speeds tomorrow.

Rapid3,
It is an alcolor system and have tried your suggestion but there is no change.

Thanks for your help guys, bill

 

[Frank Rieder]

Bill,
It certainly could be the fountain solution, but I am tending more towards settings or
an electronical problem.
Open settings of dosing roller to chrome (You did this already) and to oscillator, and check all the other
water roller too. If they squeeze to hard, you have to increase the fountain speed/%.
Check the bridge roller too, turn it off if to see if it helps.

When the plate is not too wet at 75%, that means that not enough, or not as much
as before the problem started, water is being let through or the motor doesn't turn at 75%.

If you didn't change the dampening solution and quantity, I don't think it is the culprit.
But, try a higher and lower concentration.

 

[mrheidelberg]

If you are talking about a scum on the edges of the paper, then you must be getting a picture frame effect on the actual blankets. If that is the case you could be having some kind of contamination issue via your rollers. Have you tried running a roller shampoo and given the rollers and oscillators a good clean.

The ink that you are using, the manufacturer could have changed the mix slightly giving you also the issue you are describing, maybe ask for a different batch or even ask to get the ink stiffened up a bit.

Regards.

 

[jbeniston]

First of all you have to find out what, if anything, has changed. If you've been running the same fount solution and ink successfully for 5 years and now, suddenly, you have a problem something has changed. You seem to have eliminated your ink/damp rollers in terms of quality and setting. Talk to your suppliers, has anything been changed with the ink? with the paper? with the fount solution?
Do you get the same results in straight printing? If you do, schedule a service call from the press manufacturers electrician and find out if the "speed following" program is working properly. As you point out cranking the dampening fluid is not an answer and you have to ask yourself why this works.

 

[jbeniston]

Thinking about your "hazey" problem. Has anything changed in the paper you use? Is the pH of the paper acidic? Is calcium being leached out? After running for a short time the calcium could build on the blanket and then transfer to the plate and sensitize it. If you stop for a while i.e to wash blankets; are the plates getting oxidised during the stop?
Just a thought.

 

[powerquote]

haze on sheet edge

haze on sheet edge

I once had a problem that resulted from "old" fountain solution. We had a slow period during the holidays and a batch of mixed fountain solution went unused. Something happened to it, maybe a fungus grew in it. It contaminated the whole dampening system. To get rid of it I had to clean the rollers with alcohol, the pan, and of course mix a fresh batch of fountain solution.

Bruce Moore
PowerQuote Print Estimating Software

 

[kbarz]

you can try less pressure between your ink form rollors set to the oscilators,if these are set to tight to the oscilators this will scum your sheet, and dirve you nuts,, make sure op knowes how to set them, hvae had this happen to me many times when we get new p.o on the press they turn the wrong screw..

 

[Joe Maldonado]

Pressroom Manager

Pressroom Manager

I think you have the ansewer, have you tested ink and fountain solution compatibility? for what you say I think this is your problem

 

[kbarz]

bill, you might want to try relaxing the pressure from the ink form rollors to the osiclators, to much squeeze here will give you fits with a light scum down the edge or edges of your sheet, the #4 form rollor must not be set very tight here.. kbarz

 

[mgk_print]

edges scumming

edges scumming

I fought this problem for a week while doing some hired hand presswork, with the normal operator looking over my shoulder. When I got the chance, I striped all the rollers(with the ink still on them) and found a couple of old riders and a form in each unit that wasn't making contact with the distributor on the ends. After making adjustment, problem went away. Had to almost max out adjustment on one roller, wonder if they had the wrong size in there(seen it happen). I had to live with a little bigger stripe in the middle on those rolls, but with black only, it worked out. Even the halftones cleaned up out there. I bet that fella has it reset to his "specs" again.

 

[CD102]

My guess is that the guy didn't check the rollers very often. It's also possible that he didn't know how to recognize the roller problems that the stripes were indicating. As for the roller that had to be maxed out, it could have been a bad roller cup or socket, too.

We had a couple of operators in my plant that as long as ink was going on the paper, they didn't care what was going on with the roller train. There would be silver metallic dust coming out one side of the unit, but they'd keep on running. Of course, that was the bearing and the socket grinding away. It was always a "pleasure" to follow those guys on overtime.

 

[mgk_print]

cd102

cd102

It was always a "pleasure" to follow those guys on overtime.

Then we would look like the bad guys because we had "down time" trying to fix it so we could run the job right and maybe, just maybe get done in time to have a life! Sorry, got issues.