Sheet Shrink?

[QualityPrint]

We recently ran across a stock that seems to be shrinking while it dries. Sounds crazy but the crop marks are measuring 1/32" to 3/64" shorter on the sheet than the plate both ways (gripper to tail & side to side.) It is happening on cover stock as well as text weight but only on one specific brand. This brand is a korean made paper and has run well for us in the past but recently has become FSC certified so the properties of it had to change. At first I thought that maybe we were actually printing short but have narrowed it down to this one type of paper. I don't know yet if it is happening as the dryers hit the sheet or if it is happening while it is drying in bindery... but am looking into it. I just wanted to put this out there to see if others have experienced anything like this. The tough thing is how do you match crossovers or achieve correct spine width if the sheet is changing after it is printing? I look forward to hearing your posts and feel free to ask any questions that I may have left out the answers to.
thanks

 

[jonprintz]

I've seen paper shrinkage but usually it is in a web press. You don't specify but I am assuming your problem is on a sheetfed press. The problem is likely happening as it hits the dryers and shortly afterward but some investigation on your part could determine this exactly.

Some contributing factors could be: humidity in the air before / after printing, excessive water on the printing plates, excessive heat on the dryer. If on a web press tension is a big factor.

We recently had one signature shrinking on a double parallel book run 2 up on a web press. We were able to isolate that issue to dryer heat / excessive tension.

If the work you produce on this brand of stock has crossovers you might want to think about switching to a better quality brand of stock. You will never be able to keep your spine width / crossovers matching correctly with an unstable stock.

FSC certification of the paper should not have changed any properties of it. FSC is only certifying that the paper fibers in the stock came from responsible sources.

Good luck with your problem.

 

[turbotom1052]

Good luck with creep on multi signature books

 

[printerpete]

What Brand Sheet is this?

 

[jonprintz]

Good luck with creep on multi signature books

Right. It will be impossible to accurately predict shingling on a multi signature stitched book on an unstable stock.

A perfect bound book would probably be OK as all shrinkage should be similar unless the shrinkage is far enough to require undersizing the book in order to trim correctly.

 

[QualityPrint]

It is happening on a stock called Titan (coated and dull)... I believe that some of the issue is the enviornment in our shop has been off a little due to our humidifiers not working correctly. The problem is it isn't shrinking consistantly so it is impossible to account for it in bindery accurately. The paper salesman is coming in tomorrow to take a look and hopefully he has some answers.

 

[John Arneson]

Is this a half size sheet fed press, and are you running short grain stock?

 

[QualityPrint]

We are having this issue on both of our sheetfed 40" presses. Paper guy was in today and claims he has never experienced anything like this. It can't only be happening in one shop with this paper...

 

[printerpete]

have you tried throwing a few pallets of another brand in to see what happens?

 

[Corey]

We have never experienced this problem. Strange.

 

[QualityPrint]

We are going to run a skid compiled of various brands of stocks later this week. The paper that is showing the shrinkage feels brittle and the cover stock was cracking when we were binding it. Luckily it was a perfect bind job and not a saddle stitch. Will keep you all posted...