Types of Glue Used in Printing
Here's a selection of adhesive terms and concepts that will help you communicate with your printer.
Spot Glue or Pattern Glue: When you take apart an envelope at the seams, you will notice a strip of glue sealing together two sides of the envelope blank (the flat, diecut envelope form prior to folding and gluing). Once this glue has been applied and the paper has been folded and attached, the bond is permanent. You have to destroy the bond to detach the two sides of the envelope.
You may also see pattern gluing attaching a cardboard easel to a stand-up "point of purchase display"or any two other printed elements meant to stay together permanently. In addition, you may see pattern gluing in a die-cut, folded, and glued pocket folder (notice how the pockets are folded up and glued in place).
Fugitive Glue: This is the glue that looks like "rubber cement."Often when you peel a cover wrap off the front of a magazine, you will see that a bead of this glue has been holding the two paper stocks together. Unlike pattern glue (or spot glue), fugitive glue can be removed without destroying the paper. (You just peel it off.)
You may also see fugitive glue used to attach membership cards to direct mail letters (although a new removable double-sided tape seems to be replacing this method in many cases).
Remoistenable Glue: This is the glue on the flap of an envelope. You lick the flap, and this activates the adhesive, allowing you to seal the envelope. Once the glue has been activated, the bond is permanent.
Stamps used to work this way, although now they use a pressure-sensitive adhesive that does not require moistening to be activated. You just peel them off the backing sheet and affix them to your envelope. The glue in these pre-gummed stamps is also permanent.
PUR Glue: This is a specific brand name for the hot-melt, flexible glue used in perfect binding. This glue is heated, and then caused to flow into the roughed-up spine of a perfect-bound book before the cover is attached. As the glue cools, it develops a permanent, strong bond, holding all the pages of the book in place. Due to the flexibility of the glue, the book can be opened and closed repeatedly without the glue's crumbling and the pages' falling out.
Peel and Seal: This is closely related to the glue used on stamps. On some envelopes, the "glue-strip"on the envelope flap is covered by a glossy sheet of paper. When you remove the paper strip, you can permanently seal the envelope without using the remoistenable glue that comes on standard envelopes.
Latex Glue: This is closely related to fugitive glue. This is the sealant used on the small "open-end"envelopes you receive at the bank when the teller gives you cash (for the sake of argument, let's say the ATM is broken). You can open the seal, remove some cash, and seal the envelope (once or many times). A strip of this adhesive is affixed to both the flap and the body of the envelope. When the two come together, a temporary but respectable bond is made.
This survey is a starting point only, and I'm sure there are many more adhesives I haven't mentioned. In all of these cases such qualities as permanence (or lack thereof), flexibility of the bond, and ease of use are primary concerns. Think along these lines when communicating with your printer, and ask for the qualities you need in a glue for the intended use of the final printed piece. In some cases, certain adhesives can even be applied during the press run. For instance, a large heatset web press can often do the pattern gluing in-line while the equipment is in operation. Most other glues applied to your printing jobs require a separate step.
Envelope Specs: Open Side Vs. Open End
When you are specifying envelopes--particularly large-format envelopes for booklets, catalogs, etc.--your printer may ask whether you want "open side"or "open end"envelopes. So you will be ready with an answer, here's the difference: Open-side envelopes have their flaps on the longer dimension, and open-end envelopes have their flaps on the shorter dimension. (I had mentioned this distinction in a prior issue of Quick Tips.) However, another way to distinguish these two envelope styles is by use. Specifically, open-side envelopes are often used for mailing booklets, so they are commonly referred to as "booklet envelopes,"while open-end envelopes are often used for mailing catalogs, so many printers refer to these envelopes as "catalog envelopes.”
[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.]