Applications
Perfect binding inspires with its sophisticated, clean look and great visual appeal often seen in glossy magazines and all kinds of books. Durable and economic, perfect binding is ideal for products with a high page count, such as magazines, manuals, catalogues and paperbacks. Books with a lower page count are not suitable for perfect binding which usually works best with 40 and more pages. However, products with fewer pages may still be perfect bound if the pages are made from heavy weight paper. Perfect binding is capable of holding together 300 pages and more. Both hard covers and soft covers can be implemented with this binding method.
In terms of quality, perfect binding is somewhere between saddle stitching and the ultra-durable but more expensive thread sewn binding. Companies, organisations and authors all appreciate perfect binding as a long-lasting, low to medium cost solution for a variety of printing projects with a higher page count, such as brochures, product catalogues, paperbacks, holiday catalogues and more. Perfect binding is also suitable for publications that are not used permanently, such as project papers, yearbooks, bachelor or master's theses or dissertations.
The details of perfect binding
Production technique
With industrial scale perfect binding, the sections are milled in the back and then glued which is a fast and low-priced technique.
In a first step, the interior pages or sheets of a book are gathered together (collated) one on top of the other to form a crisp block. This is different from saddle stitching, for example, where the folded sheets are nested one inside the other. For this reason, perfect binding allows processing single pages in addition to spreads and the page count does not have to be divisible by four. Moreover, different paper types and weights can be mixed and matched for the book block. We use offset paper, art paper, recycled paper and book paper in different weights ranging from thin 80 gsm quality to sturdy 250 gsm card stock.
After collating the pages, the sections are milled and roughened in the back to allow the glue to penetrate more easily and assure durable and permanent adhesion between the pages. Next, the paper dust is removed and the glue is applied using rollers or nozzles. After applying glue to the spine, a cover (hard cover or soft cover) or spine tape is pressed onto the still wet adhesive. The other three sides are then trimmed to create a brochure, catalogue or book with clean or "perfect" edges.
The entire binding process happens very quickly: State-of-the-art book and binding lines are capable of processing several thousand copies per hour.
Additional options during production
Umschlag
The cover can be made of a different paper stock or card stock, usually a thicker material. This makes the printed product more stable and adds to its visual appeal. Moreover, you can design an eye-catching layout for your cover. This must be accounted for when creating the artwork files: Cover art needs to be set up as a spread including the spine width.
You can optionally incorporate spot colours or opt for other finishing techniques to design your cover, such as matt or glossy film lamination, spot relief varnish or matt soft touch film lamination. Choosing cover flaps is another option to add extra information and give your book a high-end finish. This cover style is designed with a section that folds in on itself. It makes the cover stronger and is a great way to display large graphics or images.
Some print shops apply a strip of self-adhesive tape in different colours to cover the glue on the spine instead of using a wrap-around cover. A great effect can also be achieved by using coloured glue. We optionally apply punched holes to the perfect bound product.
Different types of glue: EVA and PUR thermal glue
Industrial scale perfect binding uses either Ethylene Vinyl Acetate (EVA) hot melt or Polyurethane Reactive (PUR) adhesive. Both thermal adhesives have their pros and cons and are suitable for different purposes. The choice of glue should thus be based on the intended application of the product.
Hot melt adhesive
Traditional hot melt adhesive is a low-priced, solvent-free thermoplastic adhesive that sets quickly. A heating element melts the glue which solidifies as it cools down. The lie-flat quality of hot-melt bound books isn't as good as that of their PUR-glued relatives. Moisture, hot and cold temperatures can affect the durability. Moreover, EVA thermal glue is more susceptible to failure, especially when using high-weight paper. This makes EVA hot melt adhesives ideal for products with a shorter life cycle and simple prints, such as (travel and product) catalogues or brochures which are updated and re-published regularly at short intervals.
PUR adhesive
Polyurethane adhesives are more expensive but also more durable and flexible than EVA hot melt. Also applied hot, PUR adhesive solidifies in a moisture-curing reaction which takes 72 hours to reach final structural integrity which is unaffected by extreme cold or hot environments. Once the glue has set, it is so strong and pliable that the spine won't crack when the book is opened and pressed down flat and offers better resistance to page pull-out. The method is much more durable and superior and yields a better open-flat behaviour than EVA hot melt binding. When processed correctly, printed products bound with PUR adhesive are as long-lasting as products with a thread sewn binding.
PUR adhesives are the glue of choice for publications with a high page count destined for a long live or heavy usage and will take your book binding projects to the next level.
What to observe with perfect binding
The relationship between paper weight and page count
The lower the paper weight of the interior pages is, the more pages can be included. The spine must be at least several millimetres thick. When using 80 gsm paper, for example, perfect binding is possible from 56 interior pages. With 250 gsm paper, only 24 pages are needed to perfect bind the product. These values refer to offset printing. Perfect binding is available from eight interior pages when producing short print runs from one copy in digital technology.
Opening behaviour
Once the glue has set, the pages of the printed product are pressed together at the spine which impairs the opening behaviour: Perfect bound brochures, catalogues and books do not open flat as is possible with saddle stitched products, for example. PUR adhesives take 72 hours before they are completely cured. Therefore, PUR bound books should not be used before this time or else their durability might suffer. This can also be a disadvantage when designing the layout: Since perfect bound books or catalogues do not open completely, parts of copy or graphics near the spine can get lost in the gutter.
Design tips
Spine strength for the cover
You have to pay attention to the spine width when setting up the artwork files for the cover. It can be calculated using the following rule of thumb: spine width in millimetres = interior pages : 2 x paper weight: 1000.
Example: A catalogue comprising 64 interior pages of 250 gsm paper weight has a spine width of 64 : 2 x 250 : 1000 = 8.00 mm
Excluding the back of the cover inside page
The glue does not adhere well to printed areas. Therefore the back of the cover inside pages should be left unprinted. Otherwise, the pages may detach from the spine already after a short time.
Imposition
We impose the inside pages of your printed product. Imposing consists of the arrangement of the pages of the catalogues, brochures and other printed products on the sheet. Therefore, please set up single pages in the artwork file instead of spreads or export consecutive singles pages to a PDF file if you have worked with spreads.
Alternatives to perfect binding
Perfect binding is a great choice for many printed publications. It is especially popular to create superior catalogues, magazines and brochures. Depending on the application and page count of the publication, other binding options may also be eligible. Here are some examples:
- Binding techniques that allow the printed product to open flat, such as wire-o binding, are recommended for training documents as well as bachelor's theses, master's thesis or other graduation papers.
- Saddle stitch binding is a good solution for printed advertising material, brochures or newspapers with low page counts. It is optionally available with loops instead of plain staples to allow the finished pieces to be inserted in a binder or lever arch file.
- Thread sewn binding is a superior and very long-lasting method of joining pages. What is more, this binding techniques allows processing products with high page counts, such as books, elegant magazines or brochures.
- Glued pad binding is the best solution for printed products that let you easily remove pages (such as pads of carbonless copy paper or notepads).
