How to Open an Envelope & Reseal It

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How long is the average letter opener?

The envelope opener is 22.7 cm/ 8.9 inches in length and 1.5 cm/ 0.6 inch in width, enough long for opening the envelopes and proper width for handling.

How do you open a sealed envelope in the microwave?

Because the heat from the microwave can cause the paper to catch fire, be extremely careful and only microwave the envelope for 10 seconds to start and then run it again for five seconds at a time, checking each time to see if the seal has loosened by gently trying to run a knife under the flap.

Steaming Open an Envelope

This is the method most people have heard of because it has been featured on tons of sitcoms where teens need to check something the school sent to their parents before their parents read it. In reality, this method should ideally only be tried if freezing fails because it’s possible the steam may warp the envelope paper and the contents inside. If the paper is too wet, be sure to lay it on a flat surface to dry.

The source of steam can be just about anything, but most people find the steam from a kettle or a mug filled with freshly boiled water to be the easiest to work with. Some people claim that using an iron on low heat with the steam on is actually more effective as there’s less moisture, reducing the chance of water damage. Once things start to loosen up a bit, use a knife to gently pry the flap up, using more steam if you notice any resistance.

To reseal the envelope, use a glue stick or liquid glue applied to a cotton swab, as the steam method does make the glue on the envelope no longer usable.


Opening an Envelope with Steam

  1. Place a tea kettle on the stove. Boil water in a tea kettle until steam begins to shoot through the spout. The steam is what you’ll use to loosen the glue in the envelope you want to open. Keep in mind that the steam method can get a little messy and potentially warp the paper, so if it’s imperative that the envelope looks fresh and new, you might want to just use a new envelope instead.
    • If the steam is coming out in a strong, steady stream, stick a spoon in the spout to diffuse it. That way it won’t be as likely to warp the paper with a thick stream of moist heat.
    • If you don’t have a tea kettle, simply boil a small pot of water until it produces steam.
  2. Place the envelope seal in the steam. Steam is hot, so you’ll probably want to use a pair of tongs or an oven mitt to hold the seal of the envelope under the steam so your hand doesn’t get burned. Hold the envelope there for about 20 seconds to give the steam time to loosen the glue.[1]
    • If your envelope is a long business-sized envelope, run the entire thing over the stream of steam to make sure each portion of the glue gets loosened.
    • Don’t hold the envelope in the steam for more than 20 seconds, or the paper will begin to warp.
  3. Use an envelope opener to lift the flap. Lay the envelope on a table and carefully run an envelope opener under the flap to loosen it. Open the flap so that you can remove the contents of the envelope. You want to open the envelope slowly enough that you don’t accidentally rip it, but quickly enough that the glue doesn’t begin to reseal.
    • If the flap doesn’t seem to be giving, and it tears slightly instead of easily lifting, place it back under the steam so you don’t end up ripping it.
  4. Let the envelope dry. After you’ve finished removing and replacing the contents of the envelope, let the envelope get completely dry before you seal it back up. In order to prevent wrinkling, lay a sheet of waxed paper over the envelope and put a heavy book on top. Pressing the envelope flat while it dries will keep it looking fresh.
    • You could also iron the envelope flat to prevent it from wrinkling. If you choose to do this, be sure not to leave the iron on the paper for more than a few seconds, since the concentrated heat can cause the paper to turn yellow or burn if you’re not careful.
  5. Reseal the envelope. The glue will have lost its tackiness after coming into contact with the steam, so you’ll have to use a different method to reseal the envelope. To reseal the envelope so that it looks as though it was never opened in the first place, try one of the following techniques:
    • Use a gluestick. Since the glue in a gluestick is relatively dry, you can use it to reseal the envelope quite discreetly. Apply glue to the edge of the flap and close the envelope. Good as new.
    • Use a wet glue. White school glue, superglue, or another type of wet glue is fine to use if you don’t have a gluestick. Just make sure you use as little as possible, so the envelope doesn’t get wrinkled with moisture.

Freezing an Envelope Open

  1. Place the envelope in a plastic freezer bag. Protecting the envelope from ice and moisture is essential, since these elements can cause it to warp. When an envelope gets wrinkled, it’s a dead giveaway that it was tampered with.
  2. Place the envelope in the freezer for several hours. The very cold temperature in the freezer will cause the glue to lose its stick. You can keep it in the freezer for as long as you need to. Make sure it’s in there for at least a few hours, or the glue might hold fast when you try to open the envelope.[2]
    • In order for this method to work, you must use the freezer, not the refrigerator. The refrigerator’s temperature isn’t cold enough to make the glue unstick.
    • If you don’t have a freezer available, try placing the envelope in a plastic bag, then submerging it in a bowl full of ice water. This is quite risky, since a leak in the bag could cause water to flow inside and ruin the envelope and its contents.
  3. Open the envelope. After a few hours in the freezer, you might be able to simply open the envelop with your fingers. If it doesn’t easily pop open, use an envelope opener or a knife to gently open the flap. If the flap still won’t budge, put the envelope back in the freezer overnight and try again.[3]
  4. Reseal the envelope. When you use the freezer method, the frozen glue loses its stick, but it gets tacky again when it thaws. To reseal the envelope, simply wait a few minutes for the envelope to warm up to room temperature, then press the flap shut. The envelope should now be sealed with no sign that it was ever opened.
    • If the flap won’t stick when you try to reseal it, use a gluestick to keep it shut.
    • If you don’t have a gluestick, use a very light application of white school glue or superglue to close it.

Opening a letter with scissors

If you are shipwrecked on a desert island and you left you left your golden letter opener in the stateroom but managed to grab a pair of scissors and you’re still having your mail delivered to you somehow, you can use your scissors to open a letter in two ways.


The first is to use a blade of the scissors as if it was a letter opener. But don’t use the sharp part—keep the scissors closed. Remember: tearing, not cutting. A butter-knife would do in a pinch. Get creative!

The second is to snip off the very edge of the envelope, but this will leave a little strip of envelope to clean up and you could cut your letter, so it is not recommended.


Photo: Stephen Johnson

Ultimately, you can open your mail however you want. There’s no mail police. Oh, wait, there is a mail police.


Reader Success Stories

  • T- Max

Jun 7, 2020

    T- Max Jun 7, 2020

    “Thanks! Was able to open a sealed bubble envelope that held a CD-R so I could mail a different CD-R to somebody else. The best part was that it readily resealed afterward!” …” more

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