What Should I Do If The Pages Of A Perfect-Bound Book Fall Out?

As a commonly used binding method, perfect-bound publications are not uncommon. However, in daily life, we often encounter problems such as loose or missing pages after perfect binding, which greatly affect the reading experience. So how exactly can printing companies operate during the perfect binding process to avoid these issues? Let's take a look!

01

Hollow Spine

A hollow spine greatly affects the appearance of a book and, in severe cases, can cause pages to come loose or detach. The reasons for a hollow spine may include serious issues with the hot-melt adhesive itself, such as impurities in the glue that create bubbles when melted. It could also be due to insufficient or uneven application of glue, inadequate contact between the glue roller surface and the book block, or poor parallelism in the operation of the glue roller. Additionally, if the glue-scraping rubber contacts the book block too tightly or is too hard, it can scrape off the applied glue, resulting in a hollow spine.

Here's how to fix it:

(2) Adjust the machine to make the surface of the glue wheel in good contact with the book core, first loosen the connecting rod nut, raise the height of the glue plate, and then loosen the fixing nut of the glue plate, so that the book core and the surface of the glue wheel are parallel and in good contact;

(3) Adjust the distance between the eraser and the book core, so that the eraser and the book core are not in close contact, or soften the eraser.

02

Glue

The opening of the glue means that the cover and the book core are not firmly bonded, which is manifested as: the front or back side glue is glued, and the front and back sides are glued or partially glued, which in severe cases causes the cover and the book core to be separated, affecting the reader's use.

If a small number of books have side glue opening phenomenon, it may be due to excessive downtime during equipment operation, the cover is not bonded and shaped within the opening time of the glue, or the thickness of the batch book is inconsistent, resulting in poor contact of the thin side adhesive.

Here's how to fix it:
(1) Minimize the number of downtimes during normal operation of the equipment;
(2) The rejected book can be reheated and flattened into qualified products by hot pressing method, without dismantling the cover and throwing it away;
(3) After folding, the air in the booklet should be reduced to ensure that the thickness of the batch book is basically the same.

If there is a side glue opening phenomenon in a batch book, there are several reasons: first, the spacing between the rubber wheels on both sides is improperly adjusted, and the contact with the book core staple is poor; second, the side adhesive model is improperly selected; third, the temperature of the side adhesive is not set according to the requirements of technical parameters; Fourth, the clamping spacing is too large when clamping.

Here's how to fix it:
(1) According to the different paper types, the type and model of adhesive should be selected correctly;
(2) Adjust the spacing of the side rubber wheel correctly according to the actual thickness of the book core to ensure uniform, stable and appropriate amount of gluing;
(3) The temperature of the rubber must be subject to the technical parameters specified by the type and model used, and the use data cannot be changed at will;
(4) Adjust the distance of the clamping block correctly, and the actual thickness of the book shall prevail, and should not be too large or too small.

03

Drop pages and scatter pages

Some offset binding hosts will have individual pages dropping when flipping, mainly for many reasons: first, the book core is not milled in place and glued when milling the back; second, the paper of the insert does not match the original book core, especially the book inserted into the core of ordinary paper with a single page of coated paper is more likely to fall off; third, the paper scraps and paper hair have not been removed, blocking the grooves, and the glue cannot penetrate; Fourth, the adhesive model is improperly selected, and the quality of the adhesive is not up to standard or the use temperature is incorrect.

The solutions are as follows:
(1) Increase the depth of milling and slotting, and change from regular glue to copperplate glue, so that the glue can penetrate to the innermost pages.
(2) Adjust the pressure, parallelism, and vertical alignment of the folding paper feed rollers so that the pages are delivered correctly, achieving tight folds without gaps.

(3) Increase the vibration amount of the vibrator to align the loose booklets neatly;

(4) Clean the used equipment regularly to ensure the cleanliness of the milling device, allowing the production to proceed smoothly.

(5) According to the usage standard requirements for hot melt glue and the type of paper used, select the correct type and model of adhesive.

04

Exposed Glue Root

When opening the first and second pages of a glued book, sometimes the hot melt glue in the spine slot can be seen, commonly called an "exposed glue root," which affects the book's appearance and functionality. This phenomenon mainly occurs for the following reasons: first, the cover paper is too hard and thick while the book core paper is too thin and soft, resulting in a large difference in strength and tension, causing the pages to tear; second, the crease pressure from flipping is too light to create a proper fold; third, the type and model of adhesive chosen are inappropriate or the adhesive quality is poor; fourth, the adhesive has aged or deteriorated, or the glue temperature is improperly adjusted.

The solutions are as follows:

(1) Select adhesives that meet the standards and are of appropriate types and models according to different paper types, and check the technical parameters of the adhesives according to the standards;

(2) Clean the glue pot regularly, and the amount of glue stored should be reasonable; the adhesive should not be repeatedly melted for a long time;

(3) When different types and qualities of paper are used within the same book, the type and model of the adhesive should be based on the best quality paper, and adhesives of different models should not be mixed;

(4) When there is a significant difference in the paper quality, thickness, and weight between the cover and the book block, the design process should include endpapers to transition the tension between the two;

(5) When the cover paper is thicker and harder, make the cover crease (side glue crease from flipping) as deep as possible, ensuring that neither the crease marks nor the paper cracks.

05

Misalignment of the text area

The binding edge refers to the bound edge of the printed product, and the binding edge width refers to the distance from the text and image area to the bound edge of the product. Some people believe that adhesive-bound books have no binding edge, which results in the text area being off-center on the page. In practical work, especially in books with title pages, this problem is particularly noticeable.

This is mainly because adhesive-bound books cannot be opened flat to the spine like sewn books. In perfect binding or glue binding, a certain width must be occupied during binding, and the binding edge width should be slightly wider than the trimming width. The groove depth for perfect-bound adhesive books is generally 1.0–1.2mm. Some printing companies have found in practice that when the binding edge is about 3mm, the text area is exactly centered, which basically also conforms to the size standards for milling the spine and grooving.