KBA marking problem

[Chris Thompson]

Having problem with C1S stock being marked on coated side. This problem is random and does not repeat sheet to sheet. 2 pictures show the marking on the coated side and the uncoated side of the sheet above. 2 different papers are being used, problem only affects 1 of them. Paper affected is .012 C1S from Tembeck, paper not affected is Tango .012 C1S. Any ideas?

 

[Anthony M.]

Hi Chris,

What is the configuration of the press?

I have already encountered a similar problem on a KBA with several varnish groups, do you have a varnish group out of pressure as a result of your printing?
The cause may be a light deposit of ink in it.

Or a deposit of ink / varnish on one of the many leaf guides in the press, causing these traces.
[From Google Translator]

 

[Chris Thompson]

No varnish or other coating. Marking/offsetting only on gripper edge.

 

[Chris Thompson]

No varnish or other coating. Marking/offsetting only on gripper edge.

And, happening on 1 manufacturers stock only.

 

[alibryan]

Setoff caused by sheet delivery.

 

[Chris Thompson]

Why not affecting both stocks and why random? Appreciate your input..

 

[alibryan]

Different stocks deliver differently because they’re made differently...and setoff is almost always random. Hard to say without being there but probably the stock having issues has more of a down-curl to it, and if so, it might be causing the gripper edge side of the sheet to contact the sheet below it. There are other possibilities, as well.

 

[turbotom1052]

Is the grain direction on both stocks being run the same?

 

[Gregory Ross]

Having problem with C1S stock being marked on coated side. This problem is random and does not repeat sheet to sheet. 2 pictures show the marking on the coated side and the uncoated side of the sheet above. 2 different papers are being used, problem only affects 1 of them. Paper affected is .012 C1S from Tembeck, paper not affected is Tango .012 C1S. Any ideas? View attachment 7290 View attachment 7291

If the transfer drums are in , take them out. you don't need them anyway

 

[Gregory Ross]

Is the grain direction on both stocks being run the same?

you're right, short grain could be a problem