Tips for Perfect Binding
 
 
Perfect Binding
Perfect Binding is a hot melt adhesive binding. The term itself was developed by the Sheridan Bookbinding machinery company in 1911when it attempted to overcome the disadvantages of cold emulsion while retaining the desirable characteristics of pull strength and flexibility. The results achieved over the past 80 years have permanently elevated perfect binding to its place of prominence. Advances in plastic hot melts have driven the marketplace to refer to all adhesive binding as perfect binding, rather than ranking it simply as part of the adhesive binding family.

Perfect binding with higher end EVA (hot melt) glues provide page pulls and flex characteristics equal to cold emulsion. The few disadvantages can all be overcome through proper planning at the design stage. The most important advantage of perfect binding is its high speed and relative low cost.

Tips for Best Perfect Binding Results:
• Allow a minimum 1/8" head, tail and face trim on inside text pages.
• Allow 1/16" to 1/8" for "grind" on spine edge of inside text pages.
• On the cover, leave an extra 1/8" at the head and an extra 1/4" at the tail of the untrimmed folded signatures. Very important!
• Make certain grain direction of cover is parallel to the spine for a more durable bind.
 
 
PUR Binding
PUR is relatively a new term as it refers to bookbinding. Actually, PUR is a hot melt adhesive similar to EVA hot melts, but the adhesive is manufactured with polyurethene reactive material (PUR). As the adhesive product dries a natural chemical reaction occurs after the glue is exposed to moisture in the air. The results of the chemical reaction creates a superior bond within the fibers of the paper giving the book a greater pull and flex strength. In most but not all product situations the books are more durable and lay flatter when opened than a typical EVA adhesive product. The disadvantages of this adhesive are that the cure time requires that the books not be used for almost 24 hours after application and the cost is slightly higher. Care should be taken when selecting this type of binding because in many instances the finished product does not require the additional cost associated with the application process.

Tips for Best PUR Binding Results:
• Allow a minimum 1/8" head, tail and face trim on inside text pages.
• Allow 1/16" to 1/8" for "grind" on spine edge of inside text pages.
• On the cover, leave an extra 1/8" at the head and an extra 1/4" at the tail of the untrimmed folded signatures. Very important!

 
 
Cold Emulsion Binding
Make certain grain direction of cover is parallel to the spine for a more durable Cold Emulsion Binding. This type of adhesive binding uses a polyvinyl acetate commonly dispersed in the form of solid resins and water. The water in the glue itself makes it near impossible to bind and trim in-line at high speed, even with high frequency dryers. However, as a result of the water base of both the glue and the paper, superior flex and pull strength characteristics make cold emulsion the most durable method of adhesive binding with the exception of sewn book blocks with soft covers.
 
 
Double Shot Hot Melt Binding
Binders continually strive to produce a better book. Some authorities claim that improved construction of the book block can be accomplished by applying a double coat of glue to the spine of the book after spine preparation. The first coat is a primer coat of glue then the block passes over a second application roller and the final adhesive coat is applied over the primer coat. This process is known in the industry as double shot hot melt. At RGSC we feel that with proper planning of your book project any necessity of this process is eliminated by using either PUR adhesive or high end EVA products. Both styles will result in a significantly reduced purchase price.
 
 
Otabind
Otabind is a process of binding patented originally by Otavia Publishing in 1981 and now licensed by Gerard Hexpoor. Basically, the books are gathered; glue is applied to the spine; then, the book block is capped covering only the glue. Next, the capping is side-glued and a cover is applied, adhering only to the side glue, detached from the spine. This process has been very successfully marketed as a "lay flat binding." By having the cover detached from the spine, the books have somewhat of a tendency to lay flatter, due to the lack of resistance of the cover glued to the spine of the book. The disadvantages of Otabind are that the binding equipment is very expensive, that the process requires the producer to purchase a license from the patent holder, and that generally it is compared to the pull and flex test of perfect binding. The greatest disadvantage is cost.
 
 
Sewn Book Block with Soft Cover
With the advent of very high-speed signature sewing machines a very popular and very durable product has been developed in the binding industry. The product is generally a simulation of case binding but with a reduced selling price due to the use of a soft cover very similar to PUR and perfect binding. The process requires all of the same steps as perfect binding but prior to the actual cover being applied to the books the signatures are sewn together creating a book that will withstand the most abusive reader. This product may be expected to perform functionally for the life of the reader but has a great disadvantage in competitive cost. Although the cost to produce this type of book is much lower than a library bound book, it remains significantly higher than any other method discussed in this paper bind.

• Consult with RGS when designing your layout.
• Remember, PUR has a 24 hour curing time requirement.
 
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