Perfect Bound Book Printing: 7 Reasons to Bind with PUR Glue

A man holding an open book over two stacks of books

estimated reading time: 4 minutes

Perfect Binding is one of the most widely used methods for creating softcover books. This binding method uses a special glue to affix the book's pages into a wraparound cover. The glue provides a strong bond to ensure the book's pages and cover stay securely bound.

There are two primary types of glue used for Perfect Binding - Polyurethane Reactive (PUR) and Ethylene Vinyl Acetate (EVA). While PUR and EVA are both hot melt glues, the high performance of PUR makes it the superior binding option for Perfect Bound books.

Below are 7 reasons why PUR glue is superior to EVA glue:

An open Perfect Bound book with fanned pages — *PUR glue gives tremendous strength and flexibility to the spine of a Perfect Bound book*

1. Higher Bonding Strength

PUR glue creates a stronger and more durable bond than EVA. PUR is a "reactive" adhesive, formulated to chemically react with moisture. The moisture, which is mostly drawn from the surrounding air but also from the substrates being bound, triggers the small molecules within the adhesive to polymerize into a larger network of molecules. This chemical reaction continues until the glue is fully cured. The molecular bonding that occurs is what gives PUR its superior strength and adhesion properties.

2. Greater Flexibility

PUR glue offers more flexibility and resilience than EVA. Because of the strong bond it creates, PUR binding only needs about half the volume of glue that EVA requires. The thinner spread of glue helps PUR remains flexible. This increased flexibility allows a perfect bound book to open very wide, thus providing for a better reading experience. Also, unlike books bound with EVA glue, books made with PUR can be pressed down flat without the risk of breaking the spine. The added flexibility also allows frequently-used books to endure repeated opening and closing of the pages.

3. More Resistant to Page Pull-Out

The robust bonding strength of PUR glue helps maintain the structural integrity of perfect bound books by ensuring the pages remain intact. Compared to EVA, PUR glue binding offers up to 60% more resistance to pages being pulled out. This feature is especially important for books that might be subject to rough handling, such as children's books or those used in rugged conditions.

A young boy looks through a large book with his mother — *PUR glue offers tremendous resistance against page pull-out. This feature is particularly important for books used by young children.*

4. Adheres to a Wider Variety of Substrates

Substrates that have a slicker surface, such as gloss coated stocks, synthetic paper, or laminated sheets, can often be a challenge for EVA glue. Recycled paper, because its shorter fibers provide less surface area on which to bond, can also be problematic for EVA. PUR, on the other hand, strongly adheres to virtually any substrate, including gloss coated stocks, synthetics, laminates, Mylar, recycled paper, and thicker cardstocks. This versatility makes PUR the ideal binding choice for a wide variety of perfect bound book projects.

5. Cleaner Appearance

As mentioned under Item #2 above, PUR only requires a thin application of glue; about half the amount needed when using EVA glue. The smaller glue line produces a neater appearance because it minimizes the potential for oozing. Also, the lower volume of glue doesn't cause the spine to bulge or distort, thus allowing it to maintain a nice square shape. PUR is also known for having good color stability, making it less likely to discolor over time. In addition, PUR dries clear, making the glue line less visible after binding.

6. Extended Open Time

PUR glue typically has a longer open time compared to EVA glue. Open time refers to the duration of time that elapses between the moment the glue is applied until the bond is made between the book's page block and cover. The extended open time of PUR provides more flexibility during the binding process, allowing more time for the precise positioning of the substrates before the glue's initial set.

A bright sun on the left and a snow covered evergreen tree on the right — *PUR glue allows Perfect Bound books to maintain structural integrity in extreme temperatures*

7. Withstands Extreme Temperatures

The spine of a book bound with EVA glue will crack if the ambient temperature gets too cold. Likewise, the pages of an EVA bound book will loosen if the temperature gets too hot. However, PUR glue maintains its flexibility and adhesion whether the temperature is well below zero or 300 degrees Fahrenheit. PUR is also unaffected by high humidity. Unlike EVA glue, PUR ensures a long-lasting and secure binding even when subject to challenging conditions.

Color Vision uses PUR Glue Exclusively

Even though PUR glue outperforms EVA in every category, there is a fair number of printing companies that still use EVA glue on Perfect Bound projects. However, Color Vision does not use EVA glue. When producing Perfect Bound books, Color Vision uses PUR exclusively.

Also, despite PUR being the superior adhesive, Color Vision does not charge extra for it. So you get all the benefits of PUR without paying more.

If you have an upcoming Perfect Bound book project and want to use PUR glue, give us a call at 800-543-6299 and we'll be happy to assist. Or, use our Quote Request form to forward your specs to us and we will send you a quote via email.

As always, we look forward to assisting with your printing and binding needs!