Chemistry Episode 3 · October 30, 2026
Why Doesn’t Glue Stick to Its Own Bottle?
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The big question
How does glue stick? And why doesn’t it get stuck inside its own bottle?
How does glue actually stick, and why doesn’t it harden inside its own bottle? Pip the puffin explores 200,000-year-old birch tar, school glue, super glue, epoxy, tape, sticky notes and the underwater glue of mussels.
Words to know
adhesion
Say it: ad-HEE-zhun
Glue grabbing onto something else, like paper or wood.
Tape sticking to a box.
cohesion
Say it: koh-HEE-zhun
Glue holding onto itself, so it doesn’t split down the middle.
A blob of dried glue that won’t pull apart.
polymer
Say it: POL-ih-mer
A long chain of thousands of little pieces, linked like beads on a string. School glue is full of them.
When glue dries, its polymer chains tangle up like spaghetti.
curing
Say it: KYOOR-ing
A chemical reaction that links tiny molecules into long chains, right where you put the glue. Super glue cures instead of drying.
Super glue cures when it touches a trace of water.
surface energy
Say it: SUR-fiss EN-er-jee
How easy a surface is for glue (or water) to spread out on and grab. Waxy, slippery surfaces have low surface energy, so glue can’t hold on.
Stickers come on waxy paper so they peel right off.
Bonus words: molecule, epoxy, pressure-sensitive adhesive, DOPA
Quiz time!
Try it at home: Sticky science tests
⏱ 10 minutes
You need
- A sticky note
- A window or mirror
- A fuzzy sweater or blanket
- A drop of water
- A piece of waxed paper
Steps
- Stick the sticky note on a clean window. Does it hold?
- Now stick it on a fuzzy sweater. Which one holds better?
- Put one drop of water on the window, and one on waxed paper. Look closely at their shapes.
- Which surface lets the water spread out? Which one makes it bead up into a ball?
What’s going on? Glue has to get really close to hold on. A smooth window lets it touch a lot; fuzz keeps it away. And water spreads flat on glass but beads up on wax, because wax has low surface energy. Glue can’t spread out on it either!
⚠️ Hot glue guns get really hot, so always ask a grown-up first.