Wonder Contributors

Today’s revisited Wonder was inspired by our Wonder Friend, Jose. Jose Wonders, “What stuff can’t get glued?” Keep WONDERing with us, Jose!

It’s one of the mysteries of life that has confounded many students throughout history. That pasty substance we all call glue…it sticks things together, but doesn’t stick to the inside of the bottle! Why not?

Is it magic? Nope! It’s science — and it’s all about water.

The regular white glue most students know so well is made up of a variety of chemicals called polymers. These polymers are long strands that are either sticky or stretchy. Glue manufacturers have to find just the right combination of sticky and stretchy polymers to make the best glue.

White glue also contains water. Water acts as a solvent that keeps the glue liquid until you want it to stick.

When you put glue on a piece of paper, the solvent — water — is exposed to air. The water eventually evaporates (changes from a liquid to a gas). As the water evaporates, the glue dries and hardens. All that’s left are the sticky polymers that hold things together. This process is called mechanical adhesion.

So why doesn’t white glue stick to the inside of the bottle? When white glue is inside a bottle, there’s not enough air inside the bottle to cause the water to evaporate to make the glue sticky. Basically, the bottle protects the glue from the air and keeps the glue runny. If you’ve ever left the top off a glue bottle for a while, you may have noticed that, unfortunately, the glue dried up!

What about super glue? You may have noticed that super glue tends to dry out in its container more quickly than white glue.

Super glue works differently than white glue. Instead of the polymers in white glue, super glue is made of a chemical called cyanoacrylate. This chemical bonds things together when it reacts with water vapor in the air. This process is called chemical adhesion.

No matter how dry the air may seem, there’s always some water vapor in the air. To keep super glue from drying out, its container must be kept tightly-sealed to prevent water vapor from seeping in and reacting with the glue.

So whether you’re talking about white glue or super glue, water is the key. With white glue, you need the bottle to keep the water in the glue from drying up and becoming sticky. Super glue containers, on the other hand, keep water out to prevent the chemical reaction that will make the glue harden.

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    • Thanks for hanging out in Wonderopolis and for letting us know how much you liked today’s Wonder of the Day®, Jo! :-)

    • Well, we have to say we are SO HAPPY to hear that, Amanda! Thank you for visiting Wonderopolis and for leaving us such a nice comment! :-)

    • Thank you for visiting Wonderopolis and for leaving such a nice comment, Sanyukta! We’re so glad that you like hanging out with us and learning new things! :-)

  1. The video was slightly creepy, BUT, it gave me info on how to keep from making a mess, or wrecking it completely.

    I didn’t know it was the water that kept if from sticking to the inside.

    • Thanks for sharing your thoughts about the video for this Wonder of the Day®, Cameron! It makes us super happy to hear that you learned something new about glue today! Have a WONDERful day! :-)

  2. Hello there,

    We wanted to know what would happen to glue if it was NOT mixed with water? What would it look like?

    Mr. Morrison’s 3rd grade class- Jacksonville, FL.

    • WOW, what another great Wonder from Mr. Morrison’s students!! We know that you’ve learned about the ingredients of glue, but we WONDER if you can do some research of your own to find out what glue without water would look like. We WONDER what the consistency and color would look like. What glue work the same if it didn’t have water in it?
      Thanks for helping us use our imaginations here at Wonderopolis– we can’t wait to hear what the AWESOME students in Mr. Morrison’s 3rd grade class have found! :)

    • Great Wonder, Chop! Thanks for sharing your very own question… we bet you can Wonder even further by taking a look at the ingredients on the bottle of glue. We Wonder what it contains? :)

    • We’re so happy you learned something new with us today, Arden and Hannah! Glue is tricky, but not so sticky inside its bottle! We hope you have a SUPER Valentine’s Day! :)

  3. I think the video needs more information than it did have. The video didn’t tell a lot about the topic but I still like the website.

    • Hi Brya! Thanks for sharing your comment with us today. We are glad you told us how we can improve our Wonder video for the future! You’re a WONDERful Wonder Friend and we’re glad you’re using your imagination with us today! :)

  4. That was one interesting video I had to pause it a lot because it was overly loud and I tried to tell mi amigo about it and I yelled but I didn’t realize until she told me lol congrats to the people who made the video good job I would like to have a wonder about why dogs tongues are so much cleaner if they lick themselves and we brush our teeth :D ;p

    • Great question, Wonder Friend! Perhaps you can do a sticky experiment to find the answer! We are so glad you shared your awesome comment! :)

    • Great Question, Mae-Mae! We think it has something to do with the fact that the less glue in one place, the quicker it will dry. Thanks for WONDERing with us today, Wonder Friend! :-)

    • What a great question, Connor! Perhaps you could ask an adult family member or friend to take a trip with you to your local hardware store to explore lots of different types of glue! We bet there are even more kinds at your local craft store too! Who knew there were so many types!

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Have you ever wondered…

  • Why doesn’t glue stick to the inside of the bottle?
  • What are polymers?
  • How does mechanical adhesion differ from chemical adhesion?

Wonder Gallery

bottle of glue_shutterstock_5363218gVimeo Video

Try It Out

Ready to have some fun with glue? Great! We thought you’d really get stuck on today’s Wonder of the Day! Ask a friend or family member to stick close to your side as you explore one or more of the following activities:

  • If you don’t have any glue on hand, that’s fine. We’re going to start by making our own homemade glue. Just follow the recipe and directions below to make your very own all-natural glue:
  • When you’re finished, pick one or more of the fun crafts below to try. Don’t forget to clean up afterward!
  • Up for a challenge? Go to the store and get a few different types of glues or adhesives. Do your own tests with them at home to see which ones dry fastest and hold the longest. You’ll need to come up with your own ways to test these concepts. Perhaps you could see how much weight each type of adhesive will hold when used to attach an object with a known weight to a board? That’s just one idea. Feel free to come up with your own creative ideas! Use a chart to track your data and, when you’re finished, create a graphic that presents your data and your conclusions. Which adhesive would you recommend? Why? Have fun exploring the scientific side of glue!

Still Wondering

Just like glue sticks to some things and not others, magnets attract some things and not others. Visit Science NetLinks’ Magnets 1: Magnetic Pick-ups lesson to learn more about which materials are attracted to magnets and which are not.

 

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