One area of significant confusion is how to make the correct artwork adjustments for Perfect or PUR bound jobs when there are images or text that cross over from the left hand page, across the spine, to the right hand page. Once you appreciate that the book cannot be opened flat (without irreparably breaking the spine and pages becoming loose) it is a short step to understand that part of the page is lost within the valley the spine creates. To create the illusion of an image or text that is continuous across the spine, some adjustment is necessary.
The binding and folding illustrations below are not exhaustive but give a good starting point (click on an image to enlarge) to gaining an understanding of the different types of available binding methods and folding schemes.
There is a single illustration for Perfect Binding but included within this category is PUR Binding and Thread Sewing. An earlier blog post considers the merits of PUR vs Perfect Binding because they are similar in method and operation. A Thread Sewn book has one major advantage over the other two; it can be opened and it will lie flat. It is also a significantly more expensive method of binding.
Our customers regularly ask us to consider and explain the merits of PUR binding over Perfect binding. These considerations are often made against a backdrop of performance and ever increasingly, price constraints. With this in mind, let’s consider the differences between PUR and perfect binding and try to contextualise when it is appropriate to PUR bind or perfect bind.
The fundamental difference between the two types of binding is the adhesive used in the process. Perfect binding uses ethylene vinyl acetate (EVA) adhesives whereas PUR uses polyurethane reactive (PUR) adhesives. Put simply, the binding really only differs by way of the type of glue used. It is the properties of each type of adhesive, however, which is important in determining which is suitable.