The commitment to the development of new solutions is closely linked to research work. Concentrol, through its four major production areas —Performance Materials, Food Processing Aids, Additives and Adhesives—, is in search of new chemical products that meet the needs of various markets. The bookbinding sector is one of the strategic sectors for the company, especially with regard to PUR Hotmelt.

In addition to PUR hotmelt for gluing the spine, conventional hotmelt is also used. Also water-based adhesive for endsheets and PSA hotmelt for the flyleaf are used.


Three phases are involved in the manufacture of a book: pre-printing, composition, and post-printing and manipulation.

  • Pre-printing

Pre-printing refers to the set of operations necessary to obtain printing forms. Among these operations there is the treatment, integration and filming of texts and images.

  • Composition

This second phase of manufacturing involves designing, printing —a set of operations necessary to obtain printing forms, such as the treatment, integration and filming of texts and images—, offset, vacuum engraving, screen printing, sealed reliefs, wrapping paper printing, continuous paper printing, digital printing, flexography printing and 3D printing.

  • Post-printing and manipulation

It is the last phase of the process and includes the operations that consist of finishing the product: cutting, folding, gluing, among other operations. It is precisely in this phase that Concentrol intervenes with its products.


Types of books

Hardcover book



It is also called “cartoné binding” in Spanish. In this system, the sheets that make up the book block are covered with a rigid cardboard cover 2 or 3 mm thick. This board is lined with paper or cloth, on which the title and cover design are printed. It is the type of binding that provides the book with the greatest appearance, strength and resistance.

It is the most expensive system, because it uses a greater number of materials, and the handling process involves more stages and greater complexity. Hardcover books are made up of a board cover, the endpapers (folded paper sheets that join the cover to the content) and the book block (sewn or glued inner pages).

In the case of luxury editions, books can be covered in fabric or leather (natural or synthetic) and are decorated with engravings, gilding, reinforcements, etc. The cheaper editions often use colour printed papers to line the cover board.


Section-sewn paperback book 


It is also known as Smyth sewn.

It is the most widely used type of binding. It consists of a thick cardboard that covers the front, spine and back cover, and that is glued to the pages of the book on the spine side. The pages of the book are grouped into booklets (usually 16 pages) that are sewn together with vegetable thread and that are subsequently glued to the cover.

This system is cheaper than the hard cover and began to be used massively at the beginning of the 20th century, when technical advances made it possible to increase the runs of books and, in this way, considerably lower production costs. In this period the first pocket editions also emerged, democratizing access to books and culture.


Perfect-bound Paperback


This type of binding is very similar to the previous one, but with a difference: the pages of the book are cut and glued directly to the cover.

It is a type of binding that is commonly used for digitally printed books, magazines, low cost editions, etc. As it is an economical system, it is the one that our online clients use the most.

In Spain it is also often referred to as the American-style glued, because it is used on a massive scale to bind pocket editions, comics, graphic novels, etc., in the United States.

The glues that were used in the past tended to lose flexibility over the years and the sheets came loose from the cover. Nowadays the glues and adhesives used stand the test of time better. Some very resistant ones have even appeared, such as PUR (polyurethane) glue that guarantee high durability, currently there are no problems of breakage with glued bindings.


Steps in hardcover book binding

The steps to make a binding vary depending on the type chosen: if it is sewn or glued or if it is a soft cover or hard cover. But, broadly speaking, we can establish the following:


  • For prefect-bound books.


  1.  Printing
  2.  Cut to separate them individually
  3.  Glue and put the cover on
  4.  Cut on all three sides to make it even
  • Per a llibres cosits


  1. Printing
  2. Folding
  3. Sorting
  4. Sewing
  5. Glue and put the cover on
  6. Cut on all three sides to make it even



Several technologies are used during the binding process: offset, vacuum etching, screen printing, embossing, wrapping paper printing, continuous paper printing, digital printing, flexographic printing and 3D printing.



Several adhesives and their following applications are involved in the manufacture of a book:


  • Water-based adhesive for endsheets (white glue) applied by roller


When we have a hardcover book in our hands and we open it, the first element we will find will be the endsheets. They are the link between the cover and the body of the book, a paper fold of which the first sheet is glued to the board and the other sheet is glued 5 mm to the book block.

The spine, contrary to what may appear at first glance, is not attached to the board and the entire weight of the book block is attached to the cover through the end sheets, if they break, the cover falls off.

In paperback bindings there are no end sheets, because they are not necessary. The book block is then glued directly to the cover.

The end sheets can be white or printed with colours, motifs or images. Normally, a different paper than that used for the pages is used, thicker and more absorbent to withstand the humidity of the glue with which it is glued to the board.


  • Hotmelt for gluing the spine, application by lip or open roller


The Spine refers to the side where the sheets of the book are attached. It contains the title, the author and the logo of the publisher.


  • Hotmelt PSA for the flyleaves, application by disc


The flyleaves are blank sheets that are placed at the beginning and at the end of the book, and depending on the category of the book, one or more are placed. Many people think that this is a waste of paper, but these sheets, apart from their aesthetic function, have a practical function. In a hardcover, the flyleaves are very important, since it is on these sheets that the end sheets will be glued and thus protect the interior from friction or glue residue.

In paperback editions they also serve as a support for the cover and are glued 3 or 4 mm. Often these sheets are used by libraries to put their stamp on, the authors their dedication, etc.

Image source: La Imprenta


  •  PUR hotmelt for gluing perfect binding


PUR perfect binding combines the advantages of both types, and more. Firstly, the cost is lower than that of the section-sewn. In addition, the strength and flexibility of this glue allow the books to be fully opened without the interior sheets detaching, unlike the standard perfect bound. All this with a shorter production time than section-sewn books.


Concentrol range


Used for gluing all kinds of substrates for bookbinding. It offers the possibility of high work rates and excellent performance.


It offers a wide versatility of gluing all types of substrates, since they can be modified according to speeds and types of materials to be joined. It does not curl and offers great bond strength on non-porous materials.


Due to their reactivity with humidity once applied, they present a high resistance, both chemical and thermal. It is sold in cylindrical containers in different weights (2Kg, 20Kg, 200Kg) in an inert atmosphere.

If we review our range of products, we see that all of them are Hot Melt products, EVA based, rubber based (Pressure sensitive adhesives self-adhesive HMPSA) and reactive Polyurethane based (HMPUR), with the exception of the Tacktrol product for covers, which is a dispersion in water.

At Concentrol we work on the development of products focused on post-printing and book handling. In our laboratories we test the effectiveness and profitability of our NETMELT, TACKTROL and NETMELT PUR solutions. In addition, we are in a constant renewing process and developing new products to meet the needs of an essential sector in the book industry.


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