Actual a2 size

Hi guyz,am having an issue with the size of the image printed on 115gsm art paper on a 4 colour MOFP press,the images don't seem to be of the same size,so my question is,if I was to take the measurements between the crop marks of the images both length and width sides,what should be the readings?

 

Is it in the lateral direction or circumferential direction?
Are you using CTP or films to plate?
Printing Long grain or short?

 

aqaz81, its on the lateral side,i use ctp plates but the problem is on both long and short grain paper,so long as its a light grammage but on heavy stock there is no problem,at times depending on the grammage,it extends to the circumferential side.

 

If its in circumferential direction than you can correct it by altering the packings and if its in lateral direction then there is nothing much you can do about it.
If the print is larger, you can reduce it by adding packing to the plate and removing the same amount from blanket and if the print is shorter then remove some packing from the plate and add to the blanket.

 

ok,thanks,let me give it a try then I will update you on the progress,I appreciate your help.

 

Isn't this a water dampening issue. A paper expansion problem..?

 

Yes it can be......

 

@simpleson @aqazi81.....please advice on the same, am considering the possibility, based on the fact that it mostly happens on thin stock, rarely does in happen on heavy stock, so, is it a case of too much water going onto the paper from the form roller or a grain disadvantage with water being the catalyst to the expansion?

 

Yes it can be a result of too much water being applied to the plate...and paper will always expand in the opposite direction of the grain....you will see this issue more on uncoated stocks as these types of substrates absorb more water than the coated substrate.
What type of dampening system is on your MOFP, Alcolor or conventional?
Can you see a thin scum line approximately 1mm on the front edge of the plate when you stop the press during printing? During printing if you look at the plate, there should be no shine on the plate......

 

@a
qazi81 very much what I see,I have an alcolor system, I have seen much of the thin line which vanishes after printing several sheets,I will reduce the water level then watch the result,for now am on a heavy stock run.