Files to be printed – avoiding mistakes

Files to be printed – avoiding mistakes

All those involved in the publishing process strive to make the printing of books as seamless and swift as possible. One of the factors that contribute to achieving this is the elimination of any mistakes that could happen while preparing the materials for printing. Below, I will try and examine the most common flaws that appear in the files prepared for printing and advise on how to avoid them.

It is often the case that even reputable publishing houses use the support of external providers to help them prepare their publications for printing or even outsource work to independent graphic designers/DTP operators. On the other hand, printing houses receive orders not only from companies that have been successfully operating on the publishing market for years, but also increasingly often—as an upshot of the greater than ever availability and capabilities of digital printing—from publishers that are new to the book selling market, frequently looking to print their first ever publication. Many of us, involved in the publishing process, are thus just learning how to properly prepare a book for printing.
Remember, the fewer mistakes at the prepress stage, the swifter the production process. Flawed file preparation means mistakes will have to be corrected. The printing house either corrects them itself, or—most often—sends the files back to the client for correction. This obviously adds to the time needed to complete the order, and sometimes leads to unnecessary emotions.

Key rules

There are a few “prime” rules to follow when preparing files for printing. First of all, as far as professional design in terms of your publishing needs is concerned, you cannot go wrong with vector graphics software such e.g. Adobe Indesign and Illustrator. Files created using those programs—irrespective of the technology to be used during printing—should be provided as PDF files:
· with no layers or transparency (flattened)
· in net size corresponding to the size of the job to print, plus any bleeds
· with a properly defined trim box
· with properly set margins
· with all fonts used in the publication enclosed.

Errare humanum est,
but let’s avoid making mistakes where we can

What proves to be the trickiest issue for people when preparing files for printing?
Perhaps it is difficult to believe, but setting an adequate bleed seems to cause the most trouble. The printed area extending beyond the expected net size of the publication is removed during the trimming process. Bleeds are the Achilles heel even for experienced publishers. They often forget to even set the bleed, while it sometimes happens that even when there are bleeds in place, they are not set right and simply too small. This applies to both interior and cover files. The absence of a bleed or the setting of an inadequate one can result in white (unprinted) lines of various width appearing on the trimmed edge of your printed publication—this is because the photos, solid and graphics do not reach the edge of the page. To correct the files simply add/increase the allowance for your bleeds by e.g. stretching the used bitmaps or extending the applied vector graphics beyond the trim edge.

Another common mistake is the absence of the so-called flap allowance or making the allowance to small—this applies to preparation of cover files for hardcover binding. This particular file defect causes white (unprinted) lines of different width to appear on your cover and significantly impair its aesthetics. These unprinted areas may be noticeable on both sides of the cover (not only on its internal pages, i.e. 2 and 3, but also on the external ones).

A different problem is presented by trim lines. These are graphic marks outside the net size showing the trim edge. Sometimes, in a document prepared for printing, the trim lines are inserted at a distance of less than 2 mm from the trim edge. What happens next? In the finished product, there will be visible residues or rather fragments of the trim lines in the form of dots or dashes on the edges of the sheets. However, when creating a PDF file, you only need to disable the insertion of trim lines (in digital printing they are redundant) or move them to a distance of minimum of 3 mm from the edge of the page. Problem solved.

A fairly common mistake is the incorrect setting of the format of the publication’s spine. Sometimes, it is incorrect thickness—inadequate to the width of the book block. In the case of unsuitable dimensions, the spine can “encroach onto” the cover pages, or vice versa: the cover pages can “encroach onto” the spine. You should remember here that smaller (narrower) book spines (less than 6 mm) cannot contain text or graphic marks, and all text and graphic elements on the spine should be placed at a distance of at least 1.5 mm from the crease (spine edge).
These are just a few of the most common mistakes encountered by the staff at a printing house every day. However, you should be aware that they are flaws that can be easily avoided.

Ready-made tools

Printers try to provide suggestions and educate their clients as the proper preparation of files for printing is half the battle when it comes to the book production process. And it lies in the interest of all those involved to prepare the files as best as possible. Therefore, printing house provides its customers with a tool to independently check and calculate the appropriate parameters for covers and dust jackets. Just use the option “Cover calculator” on the website ( to ensure that preparation of correct files for printing becomes simpler.

joanna zielinska

Joanna Zielińska

The manager of marketing at The enthusiast of so many things, that it’s possible to enumerate them in here. She likes reading and she has a sneaking suspicion that running too, if she started  finnaly 😉

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