Seeing Lines

[csawatzki]

Can anyone tell me why I might be seeing lines across a sheet, in magenta, round dot that is printed 175. Ultimately the lines run at the same angle as the dots (15 or 75), but the dots are round, so why would I see a line?

 

[gordo]

Can anyone tell me why I might be seeing lines across a sheet, in magenta, round dot that is printed 175. Ultimately the lines run at the same angle as the dots (15 or 75), but the dots are round, so why would I see a line?

It looks like there's a black printer in the photo. (M+K)
What screen angles for the 4 process colors are you running?

 

[Cornishpastythighs]

Sorry if this is way off because I cannot see much in your photo but this might help you

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

 

[gordo]

Sorry if this is way off because I cannot see much in your photo but this might help you

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

If I'm seeing what the OP is concerned about - "lines" - it wouldn't be mottle since the lines have both angle and frequency.

 

[Alois Senefelder]

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Hello csawtzki,

My opinion of this problem is that you are seeing - Secondary Scumming.


Regards, Alois

 

[aqazi81]

My opinion of this problem is that you are seeing - Secondary Scumming.


Regards, Alois

Secondary scumming???

 

[Alois Senefelder]

Secondary Scumming

Secondary Scumming

Hello fellow Lithographers,

A PDF regarding ----- which I hope will be of interest and value.


Regards, Alois

 

[aqazi81]

Thank you Alois for the PDF, I have faced this issue in metallic gold printing at the 1st unit, but if you say this issue is secondary scumming then there should be yellow scumm as the OP is running kcmy.