I received an interesting question from a PIE Blog reader today. I think many other readers will benefit from the answer. Here’s the email:
“Hi Print Industry,
“I’ve been following the Print Industry blog since I started creating a book and looking for a printing business to produce it. I have a question from the customer side, and I’m hoping to establish whether or not the printer I’ve chosen can still do the job.
“I have a book that involves two separate, but side-by-side, images on each page. The images are to be separated by a line of perforation. There’s also another perforation line because each sheet needs to tear out from the book right at the edge of the image. I was contacted by the graphics person at this printer yesterday, and he said they couldn’t get the perforation perfect on every page, so some [perforation] lines might run onto the image. [He suggested that I] put white space between the perforation and image. He said this was because of the nature of perforation on paper and implied that this would be a problem everywhere.
“Is it true that perforation can’t be right on the mark on every page, or should I be looking to leave behind my deposit and look for a printer who can do this?
“Thanks so much,
“Miranda”
This was my reply:
Miranda,
Books, in particular, are problematic, since the book printer starts with a large press sheet and folds it into a smaller signature (i.e., the press sheet is folded multiple times). Each fold can move a page slightly (and progressively) out of alignment. Therefore, when creating anything (especially a print book or other “signature-based” printed product, like a magazine), it is prudent to remember that folding is a mechanical process that is far from perfect, and to design the piece so a flaw in folding is not obvious. This includes avoiding “crossovers,” in which one graphic element continues across facing pages (unless they are side by side on an unfolded signature press sheet).
The same thing is true for other processes such as perforating, which will move slightly from sheet to sheet during the folding and trimming process.
Basically, your printer is trying to protect you from being disappointed. Some commercial printing suppliers producing some printed products on some equipment will do a better or worse job (depending on these variables: size, number of folds, operator skill, and equipment). However, this will be a challenge for all custom printing vendors, and there will be flaws. Personally, I’d defer to the suggestions of the book printer for avoiding problems–as long as you have confidence in his skill (based on his printed samples and other clients’ views of his work).
Thank you,
Steven
Implications
This PIE Blog reader’s question has several implications. Here are some thoughts:
How do you know when to trust/not trust a printer?
Like any good relationship, a relationship of mutual trust with a commercial printing supplier takes time to develop. Personally, I like to start by talking with the sales rep to get a sense of the printer’s strengths. Then I like to read the printer’s equipment list, request and review printed samples, and get some feedback on the printer from references. I check the samples closely for precision (trimming, for instance), color fidelity in the images, consistent ink coverage, and binding. Any flaws will say something not only about the printer but also about the sales rep who chose the samples. Then I start the printer off with a small job (a test). From there I gradually build a mutually supportive relationship with the printer, which takes time. Once I have developed mutual trust with the printer, I listen closely to his advice, since he will know more about his equipment and capabilities than I do.
What is reasonable tolerance?
For this kind of job, the book printers I spoke with said 1/32” in either direction. However, in a lot of print jobs, I’ve seen closer to a 1/16” tolerance (in either direction).
This means that if two halves of an image come together (as in a gatefold), there is a possibility that the image may not line up exactly across the fold (or page break). In fact, the match may be off by plus or minus 1/32” (or a total of 1/16”). In addition, the more folds your job has, the more this tolerance will add up (1/32” plus 1/32” plus 1/32”). If the fold is misaligned initially, it will get worse with each successive fold.
It is therefore prudent to discuss your job’s folding requirements with your printer and ask for suggestions about designing your job to minimize this inevitable problem. Designing signatures of a publication with this limitation in mind (for example, placing an image that crosses from page to page in the center spread of one signature rather than with half of the image on the last page of one signature and half on the first page of the following signature) can maximize alignment accuracy.
What printing/finishing processes are more challenging?
The more folds there are in a press sheet, the more problematic alignment can be. Therefore, a tri-fold brochure might be less of a challenge than a 16-page signature of a book. This is true for a fold, a perforation, or a trim. For instance, printing a rule line around the front cover of a book and expecting it to be perfectly centered on all trimmed copies of the press run is asking for trouble. If you omit the rule line, your eye will be more forgiving of any misalignment, but if the rule line is even a fraction of an inch out of alignment, it will bother you.
Basically, in my experience finishing equipment (folding, stitching, perfect binding, and trimming equipment) seems to have more fluctuation than printing equipment, and offset printing equipment seems to have a tighter tolerance (less movement of the paper) than digital printing equipment. That said, there are major improvements being made to all printing and finishing equipment (even as we speak), so the overall precision of print jobs has been improving in leaps and bounds in recent years.
The safest thing to do is ask your book printer or commercial printing supplier for advice and printed samples. If you have a good working relationship, believe what he says to you, particularly when he suggests ways to provide a superior printed product.
This entry was posted
on Wednesday, September 7th, 2016 at 10:21 pm and is filed under Book Printing.
You can follow any responses to this entry through the RSS 2.0 feed.
Both comments and pings are currently closed.