If you are anything like me, you truly admire the look and feel of a perfect bound book. However, there are some things that you may want to think about before you send your files out, for a perfect bound book…
Cross-overs: Cross-overs are any images that are split between two pages. This can be as simple as a single tone, or as complex as a circular face! Remember with any cross-over that the two pages won’t be side by side on the form AND that we have to account for the image being pulled into the gutter (a.k.a: into the spine). This is because when a reader opens up to a page with a cross-over, they don’t mash open the book so far that you can see the spine.
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Ultimately, a good pre-press team will account for this, and create slivers of mirror images in the form-layout that are only intended to act as assurances in case a cross-over opens a little further than expected.
It’s also good to know that some cross-over images are more susceptible to error, so that you can minimize their use. Cross-overs that are diagonal or circular images may open up a bit differently depending upon where they are located in a book. Additionally, any slight misfolding will miscue the cross-over.
Cross-overs have a huge significance in the press-room as well. A quality-focused production team will make accurate notation of cross-overs on page-layouts so that press-operators accurately match color. As managing cross-overs is not an exact science, there can be some slight shifting during folding as well. This can make the cross-over image on one page slightly higher than the image on the other.
Managing Spine Strength: The most common means of measuring spine-glue strength is by utilizing a page-pull test. A page-pull test is performed by a machine that essentially locks the front half of a book with one anchor and the back of the book with another anchor, and then grips onto a center page (similar to opening the book like a banana). The machine pulls on the page until it releases or tears from the spine. The industry standard is a 2.5 result, or 2.5 pounds per linear inch. Because upright and oblong books have different glue-areas/spine-lengths, oblong books tend to open flatter and sometimes, can be weaker.
The glue-type is normally dependant upon the use of the book. For casual reading, the most standard glue type, EVA, or ethylene vinyl acetate, will work fine. For very rigorous use, PUR, or polyurethane reactive glue is the best option. However, PUR glue is typically a higher material and manufacturing cost and requires a minimum 24-hour dry time.
There are numerous other concerns that printers must take into considerations to improve spine strength, like better notching standards; but for most projects, you can determine between the two most commonly utilized glue types. Additionally, as a best-practice, we knock-out ink and varnishes in the glue area to encourage better gripping of the paper fibers.
Grain Direction and Fiber Growth: There are a couple of unique considerations to remember about the paper in your book if you have printed the text on a web-press. First, you will very likely experience web-growth, which is an uneven, but approximately 1/32 to 1/16 of an inch, growth of the text beyond the face of the cover. This is naturally caused by moisture that returns to fibers after web-dryers remove it during a press-run.
If the grain direction runs parallel to the spine, this will cause waffling, which are slightly wavy pages and spine. As the fibers re-gain moisture and try to grow, the fibers put an immense strain on the fibers that are bound to the spine, causing a slight waving.
What Can Be Perfect Bound?:1.) Two-Page Signatures: Different than saddle-stitching (where the minimum signature page count is four-pages), we can bind in two-page signatures. This allows you to produce the most optimal page count for your needs. This also allows…
2.) Inserts: One of the many benefits of perfect binding is that you can bind-in nearly anything! This opens the door to be able to bind-in 2-page inserts of a variety of substrates. Sticker-pages, posters and other fold-outs, varying stocks, two-page BRCs, tear-away envelopes, magna-strip tip-ons; the options are nearly limitless. Of course, we consult with our bindery manager and production team well in advance to discuss the feasibility of an insert. But the options are significantly greater with perfect binding.
3.) Fold-Outs: Fold-outs are text or cover pages that fold-out beyond the trim of the book. When a fold-out is folded in, I would advise to plan the fold-out to be slightly smaller (1/8”) than the final trim. This allows for the perfect binder to accomplish binding in a single pass, without three-knife trimming off the fold.
4.) Tip-Ons: We accommodate tip-ons the same for perfect binding as for saddle stitching. Essentially, tip-ons are tipped on to flat-sheets prior to folding.