Photo purchased from … www.depositphotos.com
I was having a discussion recently with my fiancee about a commercial printing job I’ve been designing. She suggested that I use fugitive glue to attach the relatively few pages to a hard cover. The problem is, I told her, that fugitive glue is made specifically to come off, which doesn’t work well with a print book cover.
Under the circumstances, I thought it prudent to review with you what gluing options you have when producing a number of different types of printed materials. I’m going to separate them by their function, since that seems to be a more useful approach than just describing the various glues.
Envelopes and Stamps
Envelopes actually include two different kinds of glue in their make-up. The portions of the envelope blank that must stay bonded are glued during manufacture with a hot melt glue made to stay in place permanently. It is applied after the stack of press sheets has been die cut into flat envelope blanks (but before folding; i.e., with all sides open). Then in the finishing process, the envelope blanks are folded, and glue is applied to the flaps (all but the ones that you lick).
However, glue on the flaps themselves is a bit different. These flaps must be folded and attached by the end-user, so the spot glue that is applied must be “remoistenable.” That is, when you either lick the glue on the flap or run a wet sponge across it, this reactivates the glue, allowing it to adhere to the closed envelope before the adhesive dries again.
Not that long ago stamps worked the same way. You licked them and then stuck them on the envelope. There was no “liner sheet” to keep the glue from sticking to other stamps. Stamps were not “peel-and-stick.”
But this does raise another issue. Now stamps are like labels. They have a permanent adhesive on the back and a slick sheet of paper from which the stamp can be peeled without disturbing the glue. If you were to affix a stamp on an envelope and then try to remove it, you’d be out of luck. The glue is rather insistent, and it would tear the stamp and/or the envelope during its removal.
Labels
Here’s some more information on labels. When I was in my teens, I worked in a Red Cross blood bank for a summer. All of the bags of blood had stick-on labels with metal foil backing and exceptionally durable glue. The labels came on liners. (Interestingly enough, they did occasionally peel off the liners and stick together in clumps when you didn’t want them to.)
The issue here was that the labels absolutely had to adhere in all ambient conditions. The Red Cross blood bags were stored in walk-in refrigerators, so the labels had to endure unusual cold and still stick to the bags. If anything got wet, the labels still had to adhere. After all, without the coding numbers, a bag of Red Cross blood was either useless or a danger to one’s health.
The same idea applies to labels on wine bottles. They need to stay on the bottles when they are cold or wet (from condensation). This requires an aggressive adhesive.
Print Books
Perfect bound books are a good place to look for glue as well. In the binding process, a hot-melt glue is liquefied and then slathered into the bind edge of the press signatures after they have been either notched or ground off. The glue determines whether these pages will stay in place, year after year, decade after decade, through heavy use. (I even have some perfectly good books from the late 1800s.)
To determine the make up of book binding glue, I just did some research online. (You may want to check Google, Wikipedia, https://www.theprintinghouseltd.co.uk/blog/pur-binding-vs-perfect-binding-what-should-i-use, and https://www.ibookbinding.com/blog/bookbinding-gluing-tips-techniques-types-info/.)
“Traditional perfect (binding) relies on ethylene vinyl acetate (EVA) adhesives.
“…this makes it the weaker of the two methods and unstable in extreme hot and cold conditions.
“Polyurethane reactive adhesives (PUR adhesives; also called reactive hot melts, reactive polyurethanes or RPU adhesives) are one-part formulations that combine the initial speed of a hot melt adhesive with the strength of a structural adhesive, while PUR makes use of polyurethane reactive (PUR) adhesive.”
PUR glue is more expensive. However, I always specify it for print books for my print brokering clients. Why? Because I know it will hold the text sheets firmly in any environment. When dry (or cured), the glue will still retain its flexibility and strength. One further note, it will hold fast to a very wide selection of text paper substrates, including coated and uncoated paper and even aqueous and UV coatings, with a firm grip on the pages to resist page “pull out.”
Standees in Movie Theaters
For ten years my fiancee and I installed (or assembled) standees in movie theaters. These are the 3D cardboard marketing pieces that promote films. They include everything from the small, flat fold-ups to monstrosities that reach the ceiling.
One of the things I noticed as I sometimes spent up to eight hours at a stretch assembling these point-of-purchase displays was that hot-melt spot glue was used extensively, both to affix one cardboard piece to another (again, permanently) and to affix chop sticks (real ones) to the back of cardboard pieces. These chopsticks strengthened thin, brittle, die-cut pieces that might otherwise bend or break. This glue allowed the chop sticks to work as a “splint,” for want of a better word.
Removable Glue
I’m using this specific glue as a separate category because it can be used for a number of things. I have even seen plastic, see-through envelopes for high-end marketing booklets sealed with removable (apparently not to be confused with “fugitive”) glue.
I have seen plastic cards like ATM cards and credit cards affixed to marketing letters using this glue. I’ve even seen it used to attach the ends of self-mailers (such as marketing fold-over mailers printed on heavy stock that would need to go through the automation machinery in the Post Office without the mailer’s flapping open).
What is removable glue? It looks like rubber cement. In fact, printers call it “booger glue.” It’s exactly the opposite of the permanent glue on the sides and flaps of envelopes, as noted above.
You can even peel it off a marketing booklet cover or off the back of a mounted credit card easily with your fingers without damaging the paper stock or the card (unlike a wafer seal used to keep a self-mailer closed). It will come off the marketing piece you received in the mail without delaminating the paper, removing any of the ink, or tearing the paper. So it is very useful. It’s just not permanent. In fact, it also leaves no residue.
You may have seen this glue in the craft stores packaged as small or large dots on a rolled liner sheet. It has lots of uses, only one of which is commercial printing.
Here’s what Wikipedia says:
“Removable glue (sometimes incorrectly called fugitive glue[1]) also called credit card glue, E-z-release glue, or (colloquially) booger glue, snot glue, or gooey glue, is a low-tack adhesive that produces a removable, non-permanent joint.[2]
“Removable glues are usually available in hot melt or latex form, with low VOC emissions.[3] They can be also applied in liquid form.”
One Point of Information
Over the recent past few years I have also seen strips of glue on the marketing letter paper stock to which some of my credit cards have been affixed. This is not removable glue. It is a bit like double sided tape, although it does release the card.
The Takeaway
I’m sure there are a lot more glues I haven’t mentioned. You may want to do some online research. However, you can see that there are numerous uses for glues and numerous chemical compositions. Here’s what I would suggest that you determine before specifying the glue for a print project:
-
- Is it temporary?
-
- Or is it permanent?
- If it is temporary, will it damage the paper substrate when it is removed?
If you’re producing a print book, ask your commercial printing vendor about the durability of the binding glue. After all, a print book binding must tolerate different temperatures and a lot of hard use, particularly if you want it to last a long time. Also, since some people fold and crease the binding of a perfect-bound book, the glue must be both flexible and durable. So look into PUR glue.
If the glue is for labels used in extreme conditions, ask the printer about its weather worthiness (tolerance for high or low temperature and moisture).
Your commercial printing supplier is your best ally in determining your gluing needs.
This entry was posted
on Monday, June 13th, 2022 at 3:18 am and is filed under Adhesives.
You can follow any responses to this entry through the RSS 2.0 feed.
Both comments and pings are currently closed.