"Waves" in the book pages.

[zamir]

Dear friends,

We, at Printiv Press, Israel, are using The Indigo 7200 digital narrow press,
to print short-run books.
As the paper is fed from rolls, the A4 books are printed against
the paper grain directions, so from time to time, we are facing this problem
of "Waves'' on the inside pages. See the image below.

The customer refuses to receive these books (4000$ order!).
Has anybody an idea how to straighten the pages?
Some say, leave it alone for a few weeks at the open air and they
will get straight back and others say put them under pressure for a while.

Any help will be appreciated.

Zamir Bar-Lev
Printiv Press
Jerusalem, ISRAEL
[email protected]
www.printiv.co.il

 

[SteveSuffRIT]

The paper was printed at a different Relative Humidity (RH) then the current surrounding air. Wavy edges is from picking up extra moisture. You need to "condition" the paper. However, the spine is bound so it won't allow it to free move. I suggest you put the books in a drier (lower RH) room for several days. Test this with just a single book. You need air to flow between pages so don't put any pressure on them. Let us know if this works?

 

[zamir]

Thank you so much for your input.

Can I simply try it with a Hair Drier?
to blow gently into the pages?
I will let you know.

 

[smalloffsetpressexperts]

Could it be condensation from being so tightly wrapped in shrink wrap? They just may need to breathe?
Moisture thru the printing process may have been trapped

 

[SteveSuffRIT]

If it was printed digital, with laser toner, the fuser heat would have dried the moisture out of the paper.

 

[pippip]

I was always understood that waves in paper like that was a direct result of wrong grain direction with no way of correcting it?

OP you mention "from time to time" you experience this problem, do you mean you experience the waves from time to time or just A4 books leading to wrong grain. Do you have any past samples you've done and has the waves gone from those?

 

[Zerge]

Hello!
Some moments:
1. Did you ever work with this type of paper and inks?
1.1 Is this paper certified by the manufacturer of your printing machine?
The problem may be the incompatibility of this paper and the ink used in the work.
In this case there is no solution.
2. Humidity. Was the moisture content of the paper more or less before print?
Based on this, the room for acclimatization of the circulation should be with a humidity of 40 or 65%.
3. Is the binding done correctly? This may be a problem.
There is no elegant solution in this case, just parse one instance and see if the block has become straight.
If straightened — cut and re-put on the covers for the entire run.

Some say, leave it alone for a few weeks at the open air

I recommend you to leave it at a stable humidity of 50-55%.
Using pressure may cause the sheets to stick together (just theory).

 

[Stickman42]

Best practices says to have the book's interior paper grain parallel to the spine. Was it printed against the grain to save on paper? I can say from experience that when I printed sets of interior pages on our Xerox cut sheet machines with the grain perpendicular to the spine, the same wavy effect occurred after perfect binding. We eventually began buying our paper differently so we could run grain parallel to the spines. Reintroducing moisture may help, but environment is a big variable.

 

[Alois Senefelder]

Hello zamir,

The only practical solution for you to try and reduce "Waviness" is to open and expose every book
to a controlled - Room Temperature 20 C - 24 C - Relative Humidity 45% - 55%
Even this gives no guarantee.

Questions: 1) Was the "Waviness" seen before the Books were bound? 2) Paper - Coated/Uncoated?
3) How many 8 pg signatures per book? 4) Moisture Content of paper reel/roll?
5) Was the temperature of the Fuser monitored? 6) Was every paper delivery stack checked for (A) temperature
(B) Moisture Content?
7) Does the Height of the waviness coincide with (A) Solids/4Colour images - back to back?
8) Post a picture of a printed sheet at a slight angle, so we can see the waviness.

To Digital Printers using Electrophotographic Imaging Systems:

A primary reason for the creation of these "Waves" is the Moisture Content Differences in - Image/Non-Image Area Boundaries.

Heat creates differential moisture/ loss retention.


Regards, Alois

 

[algio]

If it was printed digital, with laser toner, the fuser heat would have dried the moisture out of the paper.

So right. It will take days to regain its moisture but it will be ok. The problem is with customers patience

 

[memador]

Hi Zamir, funny we are situated 15 minutes away from each other under the same dry weather of Jerusalem that doesn't really help with those waves, We have also experienced this problem with our wedding albums. We tried many different solutions (humidity, overnight press pressure and more) The best solution cane when we switched the direction of the paper grain. It was possible as our Indigos are sheet fed. Regards. Carlos

 

[Stickman42]

It was possible as our Indigos are sheet fed.

You can switch the grain direction of the printed book with rolls also. I looked at the spec sheet of the 7200. It says max web width is 13.4". This will fit the 11.75" height of the A4 book, but will result in grain perpendicular to the spine, and waviness. Rotate the image 90 degrees, grain parallel to spine, no waviness. More paper needed this way (and more click charges/feet through the printer), but the problem should be resolved. Which way is better? I know this doesn't help flatten what you've already bound, but might help in future job planning.

 

[zamir]

Thank you all dear friends.

I'm back after difficult period we've experienced here in Israel (Hi Carlos) due to the Corona virus including lock-downs etc.
I was really impressed of the wide spectrum of ideas and solutions you suggested.
To those who asked, I repeat, the book was printed on Indigo 7200, Roll to Sheet, so the grain direction is perpendicular to the spine.

I'm happy to tell you that the solution was found. I just left it in the open air in a room temperature and it got straightened after 2 weeks. Have a look:

I believe it will help everybody in cases like that.

Regards,
Zamir Bar-Lev

 

[smalloffsetpressexperts]

Very happy for you. I wish peace to you and Israel