Perfect Binding vs PUR Binding: What is the Difference?

Man in denim shirt pondering differences between traditional perfect binding and PUR binding

estimated reading time: 5 minutes

A Quick Overview of Traditional Perfect Binding

Traditional Perfect Binding uses Ethylene Vinyl Acetate (EVA) adhesive to fasten a book's pages within a wraparound cover. This binding method produces softcover books with a flat, printable spine.

Two study guides for a college nursing program lying on a light wood tabletop — *The Perfect Binding method yields a flat, printable spine*

EVA is a hot-melt adhesive that has been used to bind softcover books since the 1960s. Due to EVA's long association with bookbinding, it is considered to be the traditional adhesive for perfect bound books.

Regarding its chemical makeup, EVA adhesive is a co-polymer of Ethylene and Vinyl Acetate. The Ethylene provides flexibility and impact resistance, whereas the Vinyl Acetate improves the glue's adhesion and toughness.

EVA is able to bond well to uncoated paper stocks. As a result, it has a good track record for bonding the uncoated stocks used for a wide variety of books. However, EVA can experience issues when trying to bond coated paper stocks, especially slicker surfaces like gloss UV or laminates. EVA adhesive can also have some difficulty bonding to heavy cardstocks, recycled paper, and synthetic substrates.

EVA adhesive works via a thermoplastic bonding process, where it melts with heat and re-solidifies as it cools, joining the adhesive and substrates together. There is no chemical reaction during the bonding process like there is with epoxies or polyurethanes. This enables EVA to set up faster, allowing perfect bound books to progress to the trimming operation soon after gluing.

Because EVA becomes molten when heated and hardens again when it cools to room temperature, book manufacturers are able to reheat batches of glue that may have hardened, thus minimizing waste. However, the fact that EVA glue can be made soft again by reheating also means that the pages and cover could become loose if subject to higher than normal temperatures.

Another concern of using EVA glue for bookbinding is the potential for a book's spine to crack during cold temperatures. Also, compared to other adhesives like PUR, EVA has a lower bonding strength. So there is the potential for pages to come loose during heavy use or rough handling.

A stack of six softcover books — *Perfect Bound Books are neatly trimmed to produce straight edges and crisp corners*

Many book printing companies still use EVA glue because it is offers a moderately good mix of strength, flexibility, and economy, particularly for books expected to have a short-to-medium lifespan. Though EVA is not as strong or long-lasting as PUR, it does offer book manufacturers a lower cost point.

A Quick Overview of PUR Binding

PUR stands for Polyurethane Reactive, a hot-melt adhesive that starting seeing commercial use for bookbinding in the 1990s.

PUR Binding is a variant of the Perfect Binding method, with the book manufacturing process being largely the same except for using Polyurethane Reactive adhesive instead of Ethylene Vinyl Acetate (EVA).

Breaking down the name Polyurethane Reactive, the term Polyurethane refers to a string of polymers linked together by urethane bonds and Reactive means the adhesive acquires its strength from undergoing a chemical reaction.

This chemical reaction is initiated by moisture drawn from the natural humidity in the surrounding air as well as the moisture within the materials being glued. The moisture triggers small molecules within the PUR adhesive to form larger chains of molecules called polymers.

This polymerization process is what gives PUR glue its superior strength and adhesion. Whereas EVA glue might set up within minutes, PUR requires hours to gain full strength because the cross-linking of molecules continues until the glue is fully cured.

Unlike EVA adhesive, PUR cannot be reheated. However, this is a positive feature for consumers because it means the pages will not loosen should a completed book encounter a hot environment.

A book bound with PUR adhesive showing the flexibility of the spine — *One of the advantages of PUR adhesive is its superior flexibility, which enables softcover book spines to withstand stress without cracking*

In addition to being able to withstand temperature extremes better than EVA adhesive, PUR outperforms EVA in many other ways.

For example, PUR's molecular bonding with a book's paper fibers provides a stronger and longer-lasting bond than EVA. The intense gripping power of PUR ensures a book's cover and pages will remain intact even when subject to extensive use or rough handling.

The flexibility of PUR adhesive is also superior to EVA. Whereas EVA can become brittle over time, PUR will maintain its flexibility. This allows PUR books to be opened wide or pressed down flat without any concern that the spine might crack.

PUR adhesive is also compatible with a wider range of substrates. Unlike EVA adhesive, PUR can create a strong bond with virtually any substrate, including coated stocks, synthetic paper, laminates, thicker cardstocks and recycled paper.

Over the past few decades, PUR has transformed softcover bookbinding by providing a much stronger and more flexible bond than EVA. PUR binding has become the ideal choice for books that will endure frequent use, such as manuals, textbooks, catalogs, or children's books.

Key Takeaways

Traditional Perfect Binding with EVA adhesive and PUR Binding both create professional-looking softcover books. But as explained, their performance levels differ significantly.

A close up of the spine of a perfect bound book — *Because EVA adhesive forms a relatively stiff bond, it limits the flexibility of the book's spine*

EVA adhesive is a solid choice for books that use uncoated paper stocks and are intended for short to medium term use. On the other hand, the use of PUR adhesive is not limited to uncoated stocks. PUR is also the better choice for books expected to last for many years.

Are you looking for affordable Book Printing Services?

Color Vision has been producing affordable books for over four decades!

So whether you are looking to print novels, manuals, catalogs, workbooks, magazines, or any other type of book, be sure to get in touch.

In addition to low prices, we offer a wide range of printing, binding, and finishing services to help your books stand out.

Even though PUR is a superior binding adhesive, Color Vision does not charge extra for it. You will get all the benefits of PUR without paying a penny more.

If you have an upcoming project, just fill out our simple Quote Request form and we will be happy to email a quote to you. Or, if you prefer to discuss your project by phone, we can be reached at 800-543-6299.

As always, we hope to hear from you soon and look forward to assisting with your custom printing needs!