Why People Put an Envelope in the Freezer

Ever seal an envelope and immediately regret it? Maybe you left a check out or slipped the wrong card in. Or your reasons were good when you sealed it, but now are a little hazy, and you find yourself staring at that envelope like it did you wrong. That’s where the good old envelope-in-the-freezer trick comes in.
I learned about this from my grandmother, who swore by it. It sounded crazy, like one of those unjustifiably clever life hacks, so I gave it a whirl, and strangely enough, it works sometimes. It doesn’t work every time, or with every envelope, but sometimes it really does allow you to open that envelope without ripping it to smithereens. Here’s how it works, when it doesn’t, and how to go about it without making a gruesome mess.

What Is the Freezer Trick?

The envelope freezer trick is just what it sounds like. You take a sealed envelope, pop it in the freezer for a little while, and see if you can’t open the envelope without ruining it. The theory is that the freezing releases the adhesive enough you can just peel the envelope clean open. But here’s the catch: it won’t work especially well with most types of modern adhesives. Those typically found on old-school letter envelopes are those water-activated glues like the kind you lick to seal.

The Real Science Behind the Trick

So what’s the deal with this glue? Most envelopes are made with a water-based adhesive made from dextrin, a type of starch. When you lick the dash of adhesive when closing the envelope, the water activates the glue in some way. It’s used to stick the sides of the envelope together, and as the moisture evaporates, the bond is made tighter. Freezing does not melt the adhesive, or even soften it for that matter. What it does is change the texture of it. Cold tends to make the glue more brittle and thus weaker (less pliable), so you may be able to detach it from the paper and break the seal.

It’s probably not microscopic exposure to enclosed air that makes the star pop out, per se. Rather, it’s the cold changing the glue subtly; as I said, it’s not shockingly frozen you’re performing surgery on.
Quickly then: It depends on what type of glue the envelope uses, how wet you got it, and how thick the envelope is.

When the Freezer Trick Works Best

When you go to open your envelope and “pop” is the only thing to come off it, then you want the odds in your favor: the freezer method is most effective when:

• It’s a lick and seal (not the creepy peel-and-stick),
• You just sealed it,
• You only “sogged” it slightly.
• The paper is somewhat thick, not flimsy/almost foily.

When It Doesn’t Work (And Why)

I’ve had plenty of fails, also modern envelopes a la Mr. Postman. Again, peel-and-stick types; those glues are by-scrappy, pressure sensitive, chemically different glues and, alas, freezers don’t slow them down one bit. And if you pressed on super-hard while you sealed or the glue has really seeped into the fibers, just a cold treatment won’t work. You’ll likely shred the paper trying to own him.

How to Experiment With the Freezer Method (Step by Step)

If you’re still intrigued (and if your envelope type looks sufficiently optimistic), I recommend:
Seal that envelope in a reseal-able bag (to keep water from condensing on the ink inside). Put it in the freezer 1-2 hours. That should do well enough. Don’t leave it overnight (it might get damp, or start warping). Take it out and let it sit for a minute or so (so it gets cold, but hasn’t “sweated”). Then give the flap a gentle try (your fingers are fine, and a butter knife might work too). Starting at the corner, and work SLOWLY. Go slowly. If that flap fights at all, you’ll cause more damage trying to pry it open. Sorry, there are no magic tricks. Go slow, Sport.

This last bit is key: some inks (mostly jeweler’s inks) lick up a little when you slap condensation in their faces. If you really love the stuff showing thru, skip the freezer, or at least be careful. That being said, good ways to experiment (and better than freezers), include steaming: hold the envelope over a steaming kettle. Be careful not to soak it. Better ways still include carefully removing the top edge with a hot knife, buttered letter opener, and/or your much-dreaded, sharp thumb, but be careful! and leave a little to re-sealing, or pay the cost for a new envelope and start again from scratch.