Options for Gluing Print Jobs
I find that in general there’s a fair amount of overlap in life. In particular, one of the printers I used to work with employed a presswoman (an unusual occurrence, since most press operators are men) who recently became an aide for the autistic. She wound up with her client in one of my fiancee’s and my art therapy classes for the autistic just recently, when we were creating sculptures from seashells. To facilitate the project, we were using glue dots to temporarily hold the shells together before permanently bonding them with hot melt glue.
This particular aide (and former press-person) and I agreed that both kinds of glue had a major place in commercial printing (as well as in our art therapy work).
To a printer, glue dots (at least generically) are called "fugitive glue." Fugitive glue never dries. Two pieces of paper, or a credit card and a marketing letter, can be temporarily adhered to one another. When a client receives the mail package and peels off the card, she/he can easily rub off the glue without damaging the letter or the card. It’s like rubber cement.
I did some research on this substance and found that it’s high in alcohol (presumably the medium that keeps it soft and pliable). I also found that it adheres best to coated press sheets.
At this point I also remembered direct mail packages I had received that were essentially folded, multi-panel brochures on coated card stock. I had noted that (presumably) the exact same glue held these marketing products together in much the same way as wafer seals. (Wafer seals are paper or plastic, usually perforated, circles that hold the flaps of a folded mailer together so they will not come open when traveling through the high-speed automated mailing equipment in the Post Office. These allow marketers to reap a discount in postage costs if their printed products can be processed automatically and quickly. Water seals keep the folded promotional pieces closed, so the machinery doesn’t tear them up. Unfortunately, wafer seals cover or obscure part of the mailer. Moreover, trying to remove them when you receive the printed piece in the mailbox can tear the paper (or at least damage the printed graphics).
With fugitive glue, you don’t have this problem. You just apply a dot of glue to the corners of the mailer, fold over the panels, and the whole package (a self-mailer, of course, not an envelope) is postal ready and "machinable" (therefore postage discount ready). When you receive the self-mailer in the mailbox, you just peel off the fugitive glue, and the printed brochure, flyer, or booklet is perfect and pristine again. Fugitive glue doesn’t tear or delaminate the printing paper. It’s the ideal adhesive in this case.
Other Glues Used in Printing
Ironically, the other glue my fiancee and I were using in our shell sculpture class was a hot-melt glue applied with a heated glue gun. Such glue also has a place in commercial printing.
1. Hot melt glues are often used in perfect binding. Heat melts the glue, which flows between the ground (milled) edges of folded and stacked press signatures which are then attached to the paper cover of the soft-bound book. Some glues are more flexible than others, allowing for more durability of the spine and less likelihood of the pages’ coming out. But it is essentially the same process as using a glue gun to melt and apply glue. (Just an FYI, in some cases liquid glue is used for perfect binding work. There are options.)
2. Hot melt glue can also be applied in the printing and finishing process to adhere the edges of an envelope blank, converting it from a flat press sheet into a usable envelope. This is called spot glue. It is not removable (without destroying the printed product). It is permanent.
3. Hot melt glue is also used for such large format printing projects as the movie theater standees my fiancee and I used to install. In this case the die-cut movie characters were often hot melt glued to cardboard support structures (fold-up cardboard arms to support otherwise flimsy parts of the display). Similar uses are abundant in smaller point-of-purchase displays, such as the ones you see in the grocery store and pharmacy that hold various products for sale.
4. Another type of glue I want to discuss is called "remoistenable glue." You may also know this as a "gummed" seal. When I was growing up, you found this on the back of stamps you had to lick. (Now you just peel and stick. The glue is already on the stamps.) However, you still find remoistenable glue on the flap of the majority of envelopes. The glue is applied at the printer, but you "moisten" it again to reactivate the adhesive. (Moistenable, re-moistenable. It’s a bit counterintuitive, but the important thing is that you activate the adhesive again with water.)
5. Still another type of glue is used for self-stick envelope flaps. There is a paper liner over the adhesive applied to the flaps, and when you’re ready to seal the envelope, you peel off the liner and fold down the flap. The glue then seals the envelope. If you’re doing a large mailing, this will make your life a lot easier.
6. Still another option involves two strips of latex, one on the flap and one on the body of the envelope. (The first option, noted above, just has one strip of glue under the paper liner, and this sticks directly to the body of the envelope. In contrast, on the latex option with two strips of latex, one latex strip sticks to the other and to nothing else. One brand of this product is called Quick Stick latex. Presumably there are others.)
One thing to think about with glue is the shelf life of these products. Have you ever seen an older perfect bound book come apart because the glue had become brittle? I recently found that a number of envelopes I had been storing (for ten years or so) no longer had functional remoistenable glue. It had just dried up and turned yellow. Normally this would not be an issue, since in most cases you’re designing and printing materials for use right now, not in ten years. But it is worth asking your commercial printing representative about the shelf life of any glued product you plan to use over time.
My fiancee and I were in a thrift store recently, and I found an interestingly bound book. I believe it was from South America. It had a fabric cover (front and back) and looked a bit like a photo album (no spine, just a front and back cover with a wood stick in the front tied to the front cover with a fiber that went through holes in the front, through all pages, and then out through the back cover. I looked this up online and learned it was called "stick binding."
The photos I found online reminded me of photo binders and journals, in that they were made with ornate, hand-crafted paper with deckled edges. A stick running the vertical dimension of the book, parallel to where the spine would have been, kept the front and back covers straight. There were two or more holes drilled through the covers and text pages, and hemp twine, or some such fiber, was wrapped around the stick and through the holes and all pages to make the bound book rigid. It looked very rustic, organic, and elegant in all the various photos. It also looked sturdy (once the lengths of hemp twine had been pulled through all pages and then tied snugly to the binding stick, the books seemed to be rather durable).
I couldn’t find anything about the origins of the process, but it seems to be very old. Or, at the very least, it makes the books look very earthy. Ironically, there is also a modern look about them because they are reminiscent of the Velo-binding (a branded term, the generic term is strip binding) I have seen, in which a plastic strip parallel to the bind edge on the front of the book and one on the back of the book are attached to one another with plastic pins that go through all book pages. These two flat plastic sticks (again, there’s no spine) hold all pages together and rigid. What’s old is new again (loosely quoted from Jonathan Swift).
[Steven Waxman is a printing consultant. He teaches corporations how to save money buying printing, brokers printing services, and teaches prepress techniques. Steven has been in the printing industry for thirty-three years working as a writer, editor, print buyer, photographer, graphic designer, art director, and production manager.]