Solids appear lighter in leading edge

[Yuellig]

we have a Heidleberg102 S+l.
the leading edge on small solids looks lighter as if water was invading it. Not water streaks but just a bit lighter. Coming down on the water does not help. These are small squares that are effected. The other ares of color are not.
Many help?

 

[gordo]

Ink needs to flow.
Are you using take off bars aka run-off bars (ink patches placed in the non-live area of the sheet)? Take-off bars are solid area of color at least 1/4 inch deep that runs the width of the sheet. They are used in colors that have little or no coverage in the actual work in the live image area.

 

[Yuellig]

No takeoff bars
ive ran this job before and have seen it come up in other units with light colors.
the ink is pms7488, a lime yellow. It’s a very slight difference just on leading edge.
the other ares are not effected ( long stripes and blocks, just these 1/2 inch squares ).
could insufficient plate to blanket cause this? Currently at.006. Was at .004 during the run.
all rollers in good condition. Any settings on rollers that could help?
could the ink be waterlogged from previous runs?

 

[Yuellig]

Coming down on the water does not help

 

[Alois Senefelder]

Yuelig,


Show us all a GOOD picture of the problem rather than trying to describe it !!!!


Regards, Alois

 

[Yuellig]

[No message]

 

[aqazi81]

You need to provide clear pictures.

 

[Alois Senefelder]

Hello Yuelig,


Questions: Do these "WASH MARKS" appear on other jobs at the same position on the sheet ??

2) If so what is the distance from the "Lead Edge" - 1st line of printing in mm to the printed defect ????

3) DO look across the entire width of the sheet at Images in line and at the same distance.


Regards, Alois

 

[aqazi81]

Also, Is this a CMYK Job or Pantone colors? Whats the color sequence?

 

[Yuellig]

The “wash marks” do not appear in other jobs.
This is a 6up layout so it is at different positions on the sheet.
it is a pms 7488 color
I don’t think this is a water bump
It only effects about 1mm into these 1/2” squares
click on photo provided to enlarge, you’ll see it on the leading edge

 

[turbotom1052]

is the image large enough to get a densitometer aperture on it? Does the densitometer readings from gripper to tail confirm what your eyes are telling you?
Have you viewed the sheet on a different plane?

 

[Yuellig]

Too small for a densitometer
these are only a 1/2” x 1/2”
optical illusion? No, it’s definitely there

 

[Manprint]

Dont know if that helps, let ink form rollers oscillate, could be ghosting

 

[Yuellig]

Went through all variations of oscillation and point of charge.

 

[aqazi81]

The “wash marks” do not appear in other jobs.
This is a 6up layout so it is at different positions on the sheet.
it is a pms 7488 color
I don’t think this is a water bump
It only effects about 1mm into these 1/2” squares
click on photo provided to enlarge, you’ll see it on the leading edge

What's the color sequence, in my opinion it can be an ink tack issue.

 

[Lithoman]

It appears the ghosting is created by the dampening unit, is this press equipped with hickey rollers? If so try dissengagin clutch/gear and run dampener at press speed.
Good luck

 

[Yuellig]

This is Heidelberg alcolor dampening system. No hickey rollers.
The only thing that could contribute from the dampening unit is if there was slipping in the rollers due to heavy contact. It doesn’t appear in any other image on the sheet.

 

[Lithoman]

Somehow water is attacking the ink film, which is why is creating that ghosting effect, since you are using pms color, try adding some extender to the ink, this will allow you to carry heavier film w/o altering the color

 

[Yuellig]

I agreed
This specific can of ink has been used before on other jobs. Is it possible it has been contaminated with water or water logged from other runs?
it is a weak ink already and I carry a heavy film .

 

[Alois Senefelder]

Yulig and fellow Lithographers.


Enliightenment !


1) I'll rephrase the question , WHAT is the distance from the GRIP EDGE of the sheet to the "WASH MARK" image in mm ??

2) On which Press Unit are you printing this PMS colour ????

3) Have you "Tripped" the other press units off Imp. and just Printed the PMS colour ???

4) Have tried printing paper from a different paper manufacturer ??

5) I suggest that during the print run YOU also run X amount of sheets on a different paper.

6) Please do tell us your Colour Sequence !!!!! We have asked many times - for this info. !!!!!


Regarsd, Alois,


Now for your enlightenment a PDF - WASH MARKS

Wash Marks 019.pdf