Gum vs. Self-Seal Envelopes

Meet the writer: Karen Pieper

Hi, I'm Karen! I've been in the industry for 18 years and can't wait to share my perspective on all things direct mail. I'm currently the Digital Marketing Manager at Letter Jacket Envelopes and deal with tasks from managing the website, facilitating conversations with customers, and much more!

The advent of affordable,  self-seal envelopes have contested the ever-unpopular practice of licking or moistening envelope glue manually. Envelope glue’s taste and general unpleasantness has created a time-honored legacy of derision, colorful urban legends and one of the more note-worthy episodes of the TV show Seinfeld.

However, the typical “lickable” gum seal has many underappreciated advantages to other methods of self-sealing. Despite many people’s aversion to the product, it was a remarkable development in industrial technology when released and solved far more problems than it created.

Myths and Misconceptions of Gum-Seal Envelopes


The normal glue seal on an envelope is commonly called a gum seal because it is created almost entirely from a product called gum arabic. Gum arabic is made from sap extracted from two particular species of acacia trees, and it is one of the most ubiquitous industrial ingredients available because of its low cost and favorable properties.

One of the most advantageous properties of gum arabic is its even mixture of polysaccharides (starchy molecules) and glycoproteins, which are naturally adhesive molecules used in many cellular processes. The combination of long starch chains and natural “glue” proteins makes gum arabic an excellent glue or binder that is edible to humans. Millions of products use gum arabic, from marshmallows to M&Ms to an ingredient in printing ink designed to prevent running.

Gum seals are known as a “remoistenable” glue because it dries non-sticky but can be reactivated after the introduction of water. The glue is an almost permanent way to fix two non-rigid components like paper. Unlike other industrial adhesives, gum seals are incredibly stable during transport and are safe for exposure to humans.

This characteristic should put to rest all notions that licking envelopes can be hazardous to your health. A memorable episode of Seinfeld written by the deviously subversive Larry David sees main character George Costanza purchase the cheapest wedding invitations possible. In true-to-form fashion, George not only disregards notions of safety but also forces his poor fiancée to seal all of the envelopes herself by use of her own tongue. A tongue-in-cheek series of events follows where George’s fiancée then suffers fatal poisoning as a result of licking hundreds of envelopes herself.

While this sequence exhibits Seinfeld’s dark comedy to a tee, it pushes aside the facts for the sake of sardonic humor. The truth is that envelope glue is perfectly safe for human contact and always has been by design. America’s Food and Drug Administration even oversees production of envelopes in places like China, just to ensure safety. We can all safely put to rest fears of envelope gum containing harmful chemicals or insect eggs, as well as anyone sharing the tragic fate of George’s fiancée — although, admittedly, she may have been spared the even worse fate of marrying George.

Pros and Cons of Gum Envelopes


As mentioned before, gum seals are stable and have a precise level of control regarding when and where the glue is used. Licking is entirely optional, too. Moistening sponges are cheap and aptly-suited to the task of sealing envelopes, and there are many other machine-type products that rapidly print labels then moisten and seal envelopes for mass mailing campaigns.

Other products like latex seals or Peel ‘n’ Seal (PNS) envelopes are excellent for occasional personal use or individual staff situations. However, as anyone who has contended with a money deposit bag knows, the sealing flaps can have a mind of their own once the paper backing has been removed. Powerful adhesives can have a habit of sticking when and where they are not wanted.

Furthermore, the waste generated, and added actions of removing the backing, make PNS envelopes impractical for large-scale or industrialized settings. Any operation that wants to use a specialized employee or machinery for mass mailing envelopes should look to the more affordable and less involved properties of traditional gum envelopes.

Hopefully, we have eased your fears and aversion to purchasing gum seal envelopes. They are an affordable option that opens up many opportunities for large scale storage and distribution of envelopes. Take a look at our extensive product line to learn more about how versatile gum envelopes can be.

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