Sheetfed 74-5 back side TVI allways higher

[ronson]

Hello

What could cause gain to be higher on back side, allways 5-11%.
Should we make different profiles, when printing on back side?
Is this a common problem?

Regards
Ron

 

[tmason]

Try switching papers, you are getting sheet distortion, it is very common. Think about what you did to that paper on the first pass through your press. You smashed the crap out of it, you hit it with four or five units of water, then you dried it out with the IR in your delivery.

You could try...
Run delivery loads no hotter than 100 degrees (US)
Reduce pressure to a minimum and double check plate to blanket pressure
Reduce water as much as possible
If you are coating, switch to a low curl coating
Check your infeed drum grippers and timing
Clean all gripper pads and check settings
If it is a Perfector, get it checked by a mechanic

 

[RobC]

You may also want to try placing the color on the back so it does not print back-to-back with the front color bar. If you have enough room on the sheet move it towards or away from the gripper so it backs up to a "blank" spot on the front. The darker background created by printing the color bar on the front could be interfering with readings on the back of the sheet.

Also, does this problem happen with just certain text weight papers, or with cover weights too?

 

[ronson]

Thanks for responding!

Good suggestion here on what i have not thinked about

RobC: It mainly happens on text weight papers

Regards
Ron