The Secret to Strong Poly Mailers: A Quality Check Guide

WH Global Pack blog


Have you ever wondered how those plastic envelopes that carry your mail from one place to another are made so strong? They’re called poly mailers, and they’re super essential for keeping things safe while they travel. Today, we will be detectives and learn how to check if these poly mailers are top-notch!

Size Matters: Measuring Up

Start with size. Poly mailers, like shoes, must be the right size. Poly mailer manufacturer makers use a special ruler to ensure accurate dimensions. Some deviation is acceptable, but no more than a lead pencil thickness!

Feeling Thick: The Thickness Test

Next, we check how thick the poly mailer is. Thickness is like the difference between a thin t-shirt and a thick sweater. We want our mailer to be just right. To do this, we use a unique tool that can tell us if it’s the perfect kind of thick.

Stick Around: Ink That Stays Put

Now, let’s look at the ink. When there’s writing or a picture on the mailer, it needs to stay there, right? So, we do two tests. First, we stick tape on it and peel it off to see if the ink comes off. Then, we rub it a lot to ensure the ink doesn’t say goodbye.

Stretchy Yet Strong: The Stretch Test

Poly mailers need to stretch a little without breaking. Imagine pulling a rubber band; if it’s a good one, it stretches and doesn’t snap. That’s what we want for our mailers, too. We check this by pulling it in different directions to ensure it can hold your stuff without tearing.

Sealed Tight: The Edge Test

The edges of the mailer are super important. They’re like the edges of a swimming pool that keep the water in. We do a “violence test” (don’t worry, it’s not as scary as it sounds!) where we try to break it on purpose to see how tough it is. We want to make sure that no matter what, the edges don’t give up.

Stick With Me: The Adhesive Test

Lastly, we check the sticky part of the mailer. It’s like the clasp on a treasure chest. It has to be strong so nothing falls out. We ensure it’s so sticky that once it’s closed, it doesn’t open unless you want it to.

Keeping It Cool: The Temperature Test

Did you know that poly mailers also need to be good at handling hot and cold? Like ice cream melts on a sunny day and water freezes when it’s cold, poly mailers can act differently in different temperatures. We do a particular test to make sure they’re just as strong in the hot sun as they are in the chilly snow. This way, whether traveling through the desert or the mountains, your mail stays safe and sound.


So, there you have it! Now you know how to check if a poly mailer is solid and safe. Remember, whether you’re sending a letter or a big package, the poly mailer has to pass all these tests to make sure your stuff gets to where it’s going without any trouble.

Maxwell Hua

Maxwell Hua | WHpack

Rapid Manufacturing Expert

I’m Maxwell Hua from WHpack, who has been focusing on the Courier Bags business for more than 10 years. I will always be committed to writing articles about the logistics industry, hope this will help you!

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