Adhesive/Perfect Binding was first developed in the late 1920's with the development of cold glue basically an automatic process of applying cold glue to sewn or stitched book blocks.  It was used initially for the mass production of magazines and directories.  As a result, paper back books evolved based on new adhesive binding technology.
     These early attempts at "Perfect" binding used traditional flexibilised animal jelly glue, but the concept really only became viable with the development of "Synthetic resin dispersion" technology.  However, as this consisted of 40-50% water, in-line finishing machines had to be large, and therefore expensive, in order to incorporate drying facilities such as hot air carousels or high frequency drying.
    It was not until the late 1940's when hot-melt glues suitable for book binding were developed by the plastics industry that the adhesive binding process become more cost-effective and therefore more widely used.  The use of hot-melt as opposed to polyvinyl acetate (PVA) allowed much faster setting of glue as the adhesive sets a few seconds after leaving the glue tank.  The advent of hot-melt gluing permitted high-speed in-line finishing and trimming on large binding systems and also the development of more modest adhesive binding machines in terms of output and cost.
     Today, over 100 crores hot-melt adhesive bound books are produced in India alone, and this figure excludes magazines and periodicals.  This is indicative of the worldwide growth and importance of the adhesive binding process, which is further emphasized by the fact that today, in addition to paperback books and magazines, more than one third of all case bound books produced in the UK and the USA are also perfect bound as opposed to conventional thread sewing.
     During the 1980's perfect binding systems have continued to improve and become more specialized in materials handling aspects from one operation to another, in order to satisfy definite markets.
     Medium speed bookbinding with quick change over
     facilities to minimize downtime between varied short-
     run work. Like magazines, text Books, Periodicals,
     Telephone directories,   Note books.  Short run-
     bookbinding for comparatively low qualities  of technical
     reports, internal reports, etc- as commonly produced
     in in-plant printing units.

The success of perfect binding in recent years has been due to the availability of a wide range of adhesives suitable for binding most types of paper, the development of machinery to make this method a quick, reliable and profitable activity for printers and trade finishers, and of course its continued cost advantage over traditional sewn books.  Furthermore, the use of hot-melt adhesives means that books can be trimmed almost immediately, rather than waiting for a day as was necessary with cold adhesives.
    Compared with saddle stitching or side stabbing, a perfect bound book has a better appearance. A perfect bound book has a square back on which a title can be printed and each page is equally strong-there is no weak central page in each section.  perfect binding is a "prestige" product, chosen by publishers of quality magazines, financial reports and house manuals.  Compared with comb or spiral binding, widely used for internal documents, each individual sheet is more strongly bound and there is no unsightly bulging at the spine.
     Perfect binding is also far cheaper than mechanical bindings basically due to the fact that Binding is Labour oriented and maintaining large work Area and work force is expensive.  Perfect bound books are easier to handle and package.     
     At a glance, the advantages of perfect binding are as follows :
         An attractive, prestige product with a flat, square back and tight, sharp corners
         Each page is equally strong
         Cheaper than mechanical binding
         Modest capital out lay on equipment
         Savings on labour 
         The books are easier to handle and package
         A far greater range of sizes and formats can be handled by one machine with
         minimal set-up requirements,
         No special skills are required by machine operators
         High output due to rapid set-up times       

Many of the restrictions inherent in saddle stitching are avoided in perfect binding.  Up to 70mm thick books can be produced, using any combination of folded signatures, single sheets or smaller sized inserts.  The very quick set-up on perfect binding machines means that it is economical to bind as few as 20 or 30 copies.  The same machine can be used for covering sewn or wire stitched book blocks, for making pads at a much faster rate than traditional hand methods, and for making glued book blocks prior to punching and 4-side trimming.  The smaller machines are ideal for use as back up equipment to larger, high-speed lines or for preparing samples, where setting up of larger equipment would be uneconomical.

In addition to the benefits mentioned above, there are numerous advantages in having the binding facility in-house, including control over quality and delivery, ability to do samples, no unnecessary transportation of work between factories, and no arguments over short deliveries or excessive waste.  Moreover, it avoids the common problem of high prices for binding short runs.

The benefits of perfect binding having in plant is maintaining of Trade Secret jobs, no time loss between printing and binding no transportation cost, Binding Quality, Speed and Saving of Labour. 

Follow these tips to get the best results from your perfect binder and to produce books of the highest quality.

For the best appearance and easy opening of the book, ensure the paper fibers of the sections are parallel to the spine (long grain).  A long grained cover will give sharp corners at the spine, where-as a cross grained cover may give a rounded cover and reduced strength, unless the covers are scored.

To give the maximum surface area of fibers for glue adhesion, the spine preparation unit should incorporate these four stages :
1.   A multi-toothed cutter to remove folds from the signatures and roughen the fibers.
2.   An adjustable height notching unit to give V-shaped notches 6-8 mm apart 
        and 0.5 - o.75 mm deep to increase surface area on coated papers.         
3.   Dust removed by brushing and vacuum extraction.

The adhesive must be applied at the right temperature so that it flows into the notches and remains liquid until the cover is applied.  A separate pre-melt compartment ensures an even temperature through out the tank.  The optimum glue  thickness on most books is about 0.5mm by setting the glue applicator roller at 1 mm from the spine, and the reverse spinner at about 0.75 mm away.

The nipping unit applies the cover to the back of the book and forms sharp, square corners to the spine.  Cover scoring may give better results when using heavy or cross grained covers, and is necessary when a hinged cover is required.

The importance and correct use of adhesives in perfect binding can never be over emphasized.  We strongly recommend that you deal with a reputable manufacturer, preferably one with its own research laboratories, which has the knowledge and experience to recommend the grade of glue most suited to your specific type of work and equipment.
     Once you have selected the most appropriate glue, and your equipment is set up in accordance with the manufacturer's instructions, care should be taken to ensure that the adhesive is heated to the right temperature.  Failure to do this can result in a number of problems (see- Fault Finding and Solving).  If the glue roller and spinner are set correctly and the glue temperature is right, an even layer of glue will be applied to the prepared spine allowing the best possible adhesion of the cover to the book block.

Coated papers and art stock, especially heavier weights, are the most difficult to bind.  Excellent spine preparation is essential as there are fewer fibers available for glue adhesion, therefore notching is absolutely vital to maximize fiber presence and enable the maximum possible bond of the adhesive.  Testing should be carried out to determine the notching pattern which is most effective the page pull and flex tester is ideal for this purpose.  The dust produced when roughing the spine must be removed by means of brushes and efficient waste extraction, as any particles left on the spine will produce a barrier between the block and the adhesive.

Some heavy coated materials are not suitable for one-shot adhesive binding, and in these cases the best alternative is to sew the sections and then to draw the cover, on which is effectively perfect binding without the spine preparation.
     Side stitching and drawn on covering is a cheaper alternative if a flat opening book is not essential.  In this instance, the cutter unit is not used but it must be ensured that the cutting blades do not touch the wire stitches.

When setting up the machine, always test the samples prepared for strength and quality of glue application.  When the glue is cold, the cover should be torn off and the spine examined to ensure the glue is even and cover adhesion is regular.  When pages are pulled out from the center of the book, notching should be even.  The strength of adhesive binding should be tested regularly.