Mottling

[Goatneck]

Hey guys - we're seeing some mottling on our Hberg sm102 press and have tested a few different papers (some premium, some house, some text weight, some cover weight) and are still seeing some mottling and marking.

1) Are marking and mottling correlated on press? If we address the marking issues can we expect to see mottling issues to improve? We do not have double diameter cylinders so slapping and marking are big concerns on press. We have checked our packing and ink/water balance and they both look normal and according to factory specs

2) What are some recommended anti-marking jackets for this series of press?

Thanks

 

[Cornishpastythighs]

I think you may have 2 different issues on your press but here is a link to anti marking jackets

http://www.shinoda-usa.com/product-green-frog-anti-marking-jackets.html

 

[Goatneck]

Cornishpastythighs,

What else could be causing the mottling? If it's not isolated to paper or squeeze? Thanks for your help man

 

[Cornishpastythighs]

Did the Mottling and marking occur at the same time? Have you always had Mottling or did it start after a change to your process? Are you running the same ink.blankets.plate fountain solution that you have always used. Can you pin point under what conditions the Mottling began? Here's another link for you.

http://www.tappi.org/content/events/09papercon/papers/Antilla.pdf

 

[gordo]

Hey guys - we're seeing some mottling on our Hberg sm102 press and have tested a few different papers (some premium, some house, some text weight, some cover weight) and are still seeing some mottling and marking.

1) Are marking and mottling correlated on press? If we address the marking issues can we expect to see mottling issues to improve? We do not have double diameter cylinders so slapping and marking are big concerns on press. We have checked our packing and ink/water balance and they both look normal and according to factory specs

2) What are some recommended anti-marking jackets for this series of press?

Thanks

Can you use Super Blues anti-marking jackets on your sm102? Used to use them on an sm74.

There are many types of "mottling", for example; mottling related to paper such as opacity mottling, brightness mottling, gloss and/or mottling related to offset - back trap mottling and water repellence mottling.

It's basically unwanted uneven print density and color variations, spotty and cloudy appearance and graininess.

Do you have a sense as to what type you're experiencing?

 

[Goatneck]

Cornishpastythighs,

That link is very helpful as I was/am not familiar with the different types of mottling. From that link - what it looks like to me is water repellence since I see graininess. I don't think it's back trap mottling since I have seen this in single color print as well.

I have tried photographing this with my microscope but it always reflects too badly on coated stocks and a camera phone doesn't "capture" the issue.

Gordo - Cornish: I could mail a sample of something to you if that would be okay?

 

[Cornishpastythighs]

I dont think you need to mail a sample to me. I am sure with the amount of experience available to you on this site you will find the answer. The more background information you can supply to the group the better. Is the problem happening on Solids or screens. Any particular print unit.

 

[Goatneck]

I will compile some info and re-post after hours

Thanks guys

 

[Goatneck]

I see it is screens - solids typically press nice and clean. Here is some background info:


2007 Heidelberg SM102, 5C plus coater (short delivery)
Screen Angles: C-165, M-106, Y-0, K-45 - this is odd but has been in place for a while...
Round dot, 175-200 lpi, 2400 dpi
30 gauge plates
.077" quick release blankets + .016" packing for .090 blanket cylinder undercut
KCMY print order with bump unit on 1st unit
Print Guard anti-marking jackets

 

[Cornishpastythighs]

View attachment Print Mottle (1).pdf

Here's some more reading for you

 

[Goatneck]

Okay, so maybe it's our impression pressure (blanket to substrate). Can we just need to do a simpe test of backing off on pressure slightly until the image "appears" better? IS this something that most people do on each new job especially those dealing with varying substrate thicknesses?

Thanks again!

 

[jaelliott]

Not sure about the mottling problem, but we can help with the marking issues with our ICP anti-marking jackets (Thanks CornishPastyThighs for providing a link to our website). We supply anti-marking jackets for all types of press models but can customize our jackets for Heidelberg press models either with the surface characteristics or packing pre-applied. While Super Blue nets are good there is the hassle of adjusting and replacing the nets where as you just wash the surface of our jackets, much less time consuming and less up front costs when you consider the cost of the Super Blue base jacket which is more or less required for the nets to work properly. Feel free to contact me for more information or you can order them direct from Heidelberg USA or Canada as I am not sure where you are located. [email protected] or 214-886-9250 Ext. 102

 

[Pressroom Specialist]

Goatneck, where are you located? If in the NY/NJ/PA area, I can stop in at no charge. Email me at [email protected] I am the areas pressroom specialist and deal with problems like this all the time. Take a picture of the printed seet close up and email it to me.

 

[Goatneck]

Goatneck, where are you located? If in the NY/NJ/PA area, I can stop in at no charge. Email me at [email protected] I am the areas pressroom specialist and deal with problems like this all the time. Take a picture of the printed seet close up and email it to me.

Thank you - unfortunatley I am not in your area and have been burned by giving out other information in the past on forums before. We have reached out to our pressroom specialists and have them scheduled for a visit. I do appreciate your offer though!

 

[Pressroom Specialist]

feel free to reach out anytime