Book Binding Adhesive: the ins and outs of side gluing
Side gluing is an important, yet often overlooked, book binding glue application. Simply speaking, it refers to the application of a thin bead of hot melt adhesive to bind the cover insides to the first and last pages, or end sheets of a book. Although side gluing is a much smaller volume application than spine gluing, it is important for two main reasons — it forms a hinge on the cover that takes pressure off the spine when the book is flexed or opened, and it makes a finished publication more aesthetically pleasing.
There are three primary ways to apply a hot melt glue for side gluing — using a wheel-pot system, intermittent extrusion nozzles, or the use of side wires. A wheel-pot system functions by picking up molten adhesive from an open pot using two horizontal wheels. The wheels then apply the hot melt adhesive in a thin bead to both sides of the book. It is imprecise, not very adjustable, and can sometimes create book binding adhesive stringing since there is no reverse spinner roll attached.
Extrusion nozzle systems, which have a small footprint, help minimize hot melt adhesive stringing issues due to a more precise, intermittent functioning. This type of smaller, closed system has become very popular in recent years as it minimizes char build-up and can also lower overall adhesive consumption during book binding glue application.
Although somewhat primitive and imprecise, side-wire systems can also be an effective and economical choice for lower quality publications with a short life-cycle. This system uses a metal wire positioned in the spine glue applicator pot to bring up a “wave” of book binding adhesive off the roller and onto the side of the publication. Since spine glues are normally higher in viscosity than most side glues, laydown and compression can be adversely affected by using the same adhesive for both applications.
Side glues are typically either ethylene-vinyl acetate (EVA) or pressure sensitive adhesive (PSA) hot melts, with each type of adhesive offering key benefits. EVA hot melt glue, with their slow set-times and zero residual tack, offer robust adhesion, great machinability, and easier clean up. PSA hot melt adhesive for bookbinding offers infinite open-time and aggressive adhesion, while minimizing the pesky stringing that can lead to machine downtime and product defects.
H.B. Fuller offers a broad range of both EVA and PSA side-glue book binding adhesives to satisfy customer needs. Long open-time EVA adhesives, HL7216 and HL3173, have been industry-leading products for years, and our popular PSA products like HL8130XZP, HL3363, and HL3396, offer a wide range of viscosity and performance characteristics. In late 2016, we also introduced a new PSA side glue — HL8244ZP, which has already garnered favorable feedback.
Visit us online for more information about our broad range of both EVA and PSA side-glue adhesives.
Technical Manager II