PUR Binding vs. EVA Binding - Why It Matters

When it comes to perfect binding, there are really only two options as far as adhesive choices are concerned. That decision has become an easy one here at Trade Bindery Services.

Up until the mid-1990s, the long-standing traditional method for perfect binding used a hot melt adhesive called Ethylene Vinyl Acetate (EVA). EVA glues are applied with a glue pot utilizing a wheel applicator. The properties of the glue itself allow for it to be re-melted many times, thus providing little waste during production. They also have quick set points requiring a small cure time before trimming. While they are acceptable for most offset papers, issues can arise when more difficult stocks are chosen.

Developed for perfect binding in 1989, Polyurethane Reactive (PUR) adhesive has become the overwhelming preference within the binding industry. As with EVA, PUR adhesive requires the backbone of the book to be prepared in much the same way, utilizing milling knives, notching heads, and roughing and/or equalizing heads to create fiber. It is this fiber that the PUR molecularly bonds to during the curing process. While the first generations of this glue required a long set up time (often over 24 hours), the technology has improved greatly in the past decade. Current formulations of PUR attain 80% of their green strength in just a few hours.

PUR glue bonds to the book through a chemical reaction. The properties designed within the adhesive draws moisture out of the air; technically making PUR a moisture-curing product. Therefore, the application method is critical. Trade Bindery utilizes a state-of-the-art extrusion head system that applies the glue directly to the spine of the book with a slot applicator that sprays the adhesive evenly; This computer controlled system allows for precise application of the thickness, and as opposed to a PUR open method, it keeps the glue from curing in the pot. This also limits any waste and virtually eliminates any cleanup.

While PUR is slightly more expensive than EVA adhesives, the glue requires that half the thickness be applied, all while producing a much stronger, more flexible bond. Thus, the pricing between the two options becomes a wash. Unlike the white or amber color of EVA, PUR is clear, and since less is required, it yields a much more aesthetically pleasing final product. Due to PUR using smaller amounts of adhesive over EVA binding it also means that you can achieve a square spine on even the thinnest of books. Trade Bindery can produce a perfect bound book as thin as 1/16th inch (inside text); something unheard of with EVA adhesives.

PUR glue is more durable and flexible than EVA glue, and once the glue has set, it is almost impossible to tear a page out of a PUR-bound book. Page pulls using PUR adhesive can be anywhere from 50% to 70% higher than books produced with EVA. In addition, PUR is not susceptible to re-melting or cold-cracking issues. As stated, EVA is specifically designed to be re-activated when heated. Thus, if a book is placed in extreme heat, it can melt again. And in extremely cold temperatures, it can become brittle and crack. In each case the integrity of the spine becomes compromised, and the binding will fail. In contrast, once PUR is in its final solid state when applied to the book, it can never be re-activated. This is vital to consider when the final destination of a book is unknown. Consider what might happen to books in such extremes as Arizona in the summer or Alaska in the winter, and this distinction becomes clearer.

While having both options available, Trade Bindery exclusively uses PUR adhesive on all of our perfect bound books. While EVA has some positives, with the advances in printing technologies and the more prevalent use of exotic stocks for printing, there is no question the PUR adhesive is the better option.

We had to ask ourselves, why would any bindery ask their customer to choose between two options, when one is so vastly superior to the alternative? We've eliminated that guess work by dedicating our perfect binder line to PUR adhesive. Like Trade Bindery, it's not only the best choice to ensure the quality of your project, it's the right choice!

Trade Bindery Services - Big enough to do the job; small enough to care.

perfectbinder_promopic_fullsize

NEW TO OUR FLOOR!
Kolbus Perfect Binding with PUR Gluing

 

QuickQuote_secondary

PUR Binding vs. EVA Binding - Why It Matters

When it comes to perfect binding, there are really only two options as far as adhesive choices are concerned. That decision has become an easy one here at Trade Bindery Services.

Up until the mid-1990s, the long-standing traditional method for perfect binding used a hot melt adhesive called Ethylene Vinyl Acetate (EVA). EVA glues are applied with a glue pot utilizing a wheel applicator. The properties of the glue itself allow for it to be re-melted many times, thus providing little waste during production. They also have quick set points requiring a small cure time before trimming. While they are acceptable for most offset papers, issues can arise when more difficult stocks are chosen.

Developed for perfect binding in 1989, Polyurethane Reactive (PUR) adhesive has become the overwhelming preference within the binding industry. As with EVA, PUR adhesive requires the backbone of the book to be prepared in much the same way, utilizing milling knives, notching heads, and roughing and/or equalizing heads to create fiber. It is this fiber that the PUR molecularly bonds to during the curing process. While the first generations of this glue required a long set up time (often over 24 hours), the technology has improved greatly in the past decade. Current formulations of PUR attain 80% of their green strength in just a few hours.

PUR glue bonds to the book through a chemical reaction. The properties designed within the adhesive draws moisture out of the air; technically making PUR a moisture-curing product. Therefore, the application method is critical. Trade Bindery utilizes a state-of-the-art extrusion head system that applies the glue directly to the spine of the book with a slot applicator that sprays the adhesive evenly; This computer controlled system allows for precise application of the thickness, and as opposed to a PUR open method, it keeps the glue from curing in the pot. This also limits any waste and virtually eliminates any cleanup.

While PUR is slightly more expensive than EVA adhesives, the glue requires that half the thickness be applied, all while producing a much stronger, more flexible bond. Thus, the pricing between the two options becomes a wash. Unlike the white or amber color of EVA, PUR is clear, and since less is required, it yields a much more aesthetically pleasing final product. Due to PUR using smaller amounts of adhesive over EVA binding it also means that you can achieve a square spine on even the thinnest of books. Trade Bindery can produce a perfect bound book as thin as 1/16th inch (inside text); something unheard of with EVA adhesives.

PUR glue is more durable and flexible than EVA glue, and once the glue has set, it is almost impossible to tear a page out of a PUR-bound book. Page pulls using PUR adhesive can be anywhere from 50% to 70% higher than books produced with EVA. In addition, PUR is not susceptible to re-melting or cold-cracking issues. As stated, EVA is specifically designed to be re-activated when heated. Thus, if a book is placed in extreme heat, it can melt again. And in extremely cold temperatures, it can become brittle and crack. In each case the integrity of the spine becomes compromised, and the binding will fail. In contrast, once PUR is in its final solid state when applied to the book, it can never be re-activated. This is vital to consider when the final destination of a book is unknown. Consider what might happen to books in such extremes as Arizona in the summer or Alaska in the winter, and this distinction becomes clearer.

While having both options available, Trade Bindery exclusively uses PUR adhesive on all of our perfect bound books. While EVA has some positives, with the advances in printing technologies and the more prevalent use of exotic stocks for printing, there is no question the PUR adhesive is the better option.

We had to ask ourselves, why would any bindery ask their customer to choose between two options, when one is so vastly superior to the alternative? We've eliminated that guess work by dedicating our perfect binder line to PUR adhesive. Like Trade Bindery, it's not only the best choice to ensure the quality of your project, it's the right choice!

Trade Bindery Services - Big enough to do the job; small enough to care.

perfectbinder_promopic_fullsize

NEW TO OUR FLOOR!
Kolbus Perfect Binding with PUR Gluing

 
Trade Bindery Service 35400 Plymouth Road Livonia, MI 48150 734-425-7500 www.tradebindery.net