Twenty-two, Winter 1999
the Facts About Adhesive
By Brandon Rasch, Vice President © 2001
Bookbinding...Literally the term may be defined, from a historical viewpoint,
as "a process of joining together a number of leaves or folios within covers
to form a codex or book," (as opposed to a roll or scroll). Many well-known
works have been gathered in sections to form a bookThe Bible and the Koran
to name a couple.
Over thousands of years, this process has evolvedfrom etching in stone
tablets to high speed 6 color offset printingto meet ever-changing needs
of writers, publishers, printers, bookbinders and, most of all, the public.
From early times, bookbinding was a highly respected art form. Ancient editions
of The Bible represent some extremely ornate decorations and have become valuable
as collectors' items. The gamut therefore ranges from the very valuable to the
ten cent novel.
Actually the ten cent novel is the bookbinding industry's answer to the proliferation
of books at an economical price. In fairly large quantities, some book products
can be gathered, bound (glued together) and trimmed for approximately ten cents.
This form of bookbinding is generically known as perfect binding. In reality,
perfect binding is one of many forms of adhesive binding.
According to Webster, adhesion is "the act or state of being united" It is "molecular
force exerted across the surface of contact between unlike liquids and solids
which resist their separation." Simply put, it means clinging, sticking fast,
tenacious. In adhesive binding, the signatures (a group of pages printed on
one sheet) are gathered in proper sequence; the spine or "backbone" of the book
receives a "grind" so the adhesive can penetrate into the paper; a coating of
adhesive material is applied to the prepared spine; and then the cover is applied
to permanently bond the leaves together within the cover.
The first mention of adhesive binding, as the term is used, appeared in a patent
issued in 1887 in the United States to Horace L. Arnold. After 100 years we
are now confronted with terms such as Otabind, PUR, EVA, Perfect Binding, Lay
Flat, Burst Binding, RepKover, Falberg and terms so numerous it would be impossible
to name them all.
As a purchaser or seller of these products, how do you know what to buy or sell,
when to buy or sell it, and how much should it cost? In the following paragraphs
I will attempt to concisely explain the answers to these questions.
As mentioned earlier, adhesive binding is a generic term that can be used to
describe only in general terms the form of a final finished product. Within
the term "adhesive binding" one would find several major categories. They are
PUR binding, perfect binding, cold emulsion binding, double shot hot melt binding,
otabinding and sewn book block soft cover 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.
Perfect Binding is a hot melt adhesive binding. The term itself was developed
by the Sheridan Bookbinding machinery company in 1911 when 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
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.
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
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 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
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.
Additional information is available from RGS on any of these processes. Just
call us at 713 or 800-785-5750 or Email
us your questions.
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