Why Is Glue Sticky?

Chloe Effron
Chloe Effron

WHY? is our attempt to answer all the questions every little kid asks. Do you have a question? Send it to why@mentalfloss.com.

There are different kinds of glue. Let's talk about the glue you probably use in school—white glue. Glue is adhesive, or sticky. It is also cohesive. That means it sticks to itself. So how does glue do that? Glue is made of polymers (POLL-uh-murrs), which are big molecules (MOLL-uh-kyools) made up of smaller molecules all joined together. The polymers that make up glue are strong, flexible, and spreadable. These qualities help it to stick to paper, plastic, glass, wood, and other surfaces.

Glue also has another important ingredient: water. When you squeeze a glue bottle and the glue comes out, air touches it. That causes the water in the glue to evaporate, or change from a liquid to a gas. When the water evaporates, only the sticky polymers remain in the glue. Without water, the glue dries, gets hard, and keeps your artwork in one piece. That’s called mechanical adhesion (muh-CAN-ick-all add-HEE-zhun). Guess what? Glue doesn’t dry out inside the bottle.

If you close a glue container up tight when you’re finished with it, there will be very little air inside. Since the water in the glue is not exposed to much air, it doesn’t have a chance to evaporate. That keeps the glue from drying out. There are many kinds of glue, and different glues work in different ways. Scientists are always looking for new and better types of glue. They have discovered that some natural glues even work under water!

Some amazing marine animals like mussels make their own glue. That’s why mussels can stick to rocks even underwater. This natural glue is different from regular white glue that comes in a bottle. It is made of proteins. Scientists have learned how to copy mussel glue and mix it with something called biofilm (a kind of slime made by bacteria) to make an even stronger glue. This glue is so powerful that it can help fix ships under water and help heal wounds without using stitches. Pretty cool, huh?

Want to make your own glue? Check out this recipe. And for more sticky facts about how mussels make their own glue, watch the video below.  


Take Advantage of Amazon's Early Black Friday Deals on Tech, Kitchen Appliances, and More

Amazon
Amazon

This article contains affiliate links to products selected by our editors. Mental Floss may receive a commission for purchases made through these links.

Even though Black Friday is still a few days away, Amazon is offering early deals on kitchen appliances, tech, video games, and plenty more. We will keep updating this page as sales come in, but for now, here are the best Amazon Black Friday sales to check out.

Kitchen

Instant Pot/Amazon

- Instant Pot Duo Plus 9-in-115 Quart Electric Pressure Cooker; $90 (save $40) 

- Le Creuset Enameled Cast Iron Signature Sauteuse 3.5 Quarts; $180 (save $120)

- KitchenAid KSMSFTA Sifter with Scale Attachment; $95 (save $75) 

- Keurig K-Mini Coffee Maker; $60 (save $20)

- Cuisinart Bread Maker; $88 (save $97)

- Anova Culinary Sous Vide Precision Cooker; $139 (save $60)

- Aicook Juicer Machine; $35 (save $15)

- JoyJolt Double Wall Insulated Espresso Mugs - Set of Two; $14 (save $10) 

- Longzon Silicone Stretch Lids - Set of 14; $13 (save $14)

HadinEEon Milk Frother; $37 (save $33)

Home Appliances

Roomba/Amazon

- iRobot Roomba 675 Robot Vacuum with Wi-Fi Connectivity; $179 (save $101)

- Fairywill Electric Toothbrush with Four Brush Heads; $19 (save $9)

- ASAKUKI 500ml Premium Essential Oil Diffuser; $22 (save $4)

- Facebook Portal Smart Video Calling 10 inch Touch Screen Display with Alexa; $129 (save $50)

- Bissell air320 Smart Air Purifier with HEPA and Carbon Filters; $280 (save $50)

Oscillating Quiet Cooling Fan Tower; $59 (save $31) 

TaoTronics PTC 1500W Fast Quiet Heating Ceramic Tower; $55 (save $10)

Vitamix 068051 FoodCycler 2 Liter Capacity; $300 (save $100)

AmazonBasics 8-Sheet Home Office Shredder; $33 (save $7)

Ring Video Doorbell; $70 (save $30) 

Video games

Sony

- Marvel's Spider-Man: Game of The Year Edition for PlayStation 4; $20 (save $20)

- Marvel's Avengers; $27 (save $33)

- Minecraft Dungeons Hero Edition for Nintendo Switch; $20 (save $10)

- The Last of Us Part II for PlayStation 4; $30 (save $30)

- LEGO Harry Potter: Collection; $15 (save $15)

- Ghost of Tsushima; $40 (save $20)

BioShock: The Collection; $20 (save $30)

The Sims 4; $20 (save $20)

God of War for PlayStation 4; $10 (save $10)

Days Gone for PlayStation 4; $20 (save $6)

Luigi's Mansion 3 for Nintendo Switch; $40 (save $20)

Computers and tablets

Microsoft/Amazon

- Apple MacBook Air 13 inches with 256 GB; $899 (save $100)

- New Apple MacBook Pro 16 inches with 512 GB; $2149 (save $250) 

- Samsung Chromebook 4 Chrome OS 11.6 inches with 32 GB; $210 (save $20) 

- Microsoft Surface Laptop 3 with 13.5 inch Touch-Screen; $1200 (save $400)

- Lenovo ThinkPad T490 Laptop; $889 (save $111)

- Amazon Fire HD 10 Tablet (64GB); $120 (save $70)

- Amazon Fire HD 10 Kids Edition Tablet (32 GB); $130 (save $70)

- Samsung Galaxy Tab A 8 inches with 32 GB; $100 (save $50)

Apple iPad Mini (64 GB); $379 (save $20)

- Apple iMac 27 inches with 256 GB; $1649 (save $150)

- Vankyo MatrixPad S2 Tablet; $120 (save $10)

Tech, gadgets, and TVs

Apple/Amazon

- Apple Watch Series 3 with GPS; $179 (save $20) 

- SAMSUNG 75-inch Class Crystal 4K Smart TV; $998 (save $200)

- Apple AirPods Pro; $169 (save $50)

- Nixplay 2K Smart Digital Picture Frame 9.7 Inch Silver; $238 (save $92)

- All-New Amazon Echo Dot with Clock and Alexa (4th Gen); $39 (save $21)

- MACTREM LED Ring Light 6" with Tripod Stand; $16 (save $3)

- Anker Soundcore Upgraded Bluetooth Speaker; $22 (save $8)

- Amazon Fire TV Stick with Alexa Voice Remote; $28 (save $12)

Canon EOS M50 Mirrorless Camera with EF-M 15-45mm Lens; $549 (save $100)

DR. J Professional HI-04 Mini Projector; $93 (save $37)

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The Great Tryptophan Lie: Eating Turkey Does Not Make You Tired

H. Armstrong Roberts/iStock via Getty Images
H. Armstrong Roberts/iStock via Getty Images

While you’re battling your kids for the best napping spot after Thanksgiving dinner, feel free to use this as a diversion tactic: It’s a myth that eating turkey makes you tired.

It’s true that turkey contains L-Tryptophan, an amino acid involved in sleep. Your body uses it to produce a B vitamin called niacin, which generates the neurotransmitter serotonin, which yields the hormone melatonin, which helps regulate your sleeping patterns. However, plenty of other common foods contain comparable levels of tryptophan, including other poultry, meat, cheese, yogurt, fish, and eggs.

Furthermore, in order for tryptophan to produce serotonin in your brain, it first has to make it across the blood-brain barrier, which many other amino acids are also trying to do. To give tryptophan a leg up in the competition, it needs the help of carbohydrates. Registered dietitian Elizabeth Somer told WebMD that the best way to boost serotonin is to eat a small, all-carbohydrate snack a little while after you’ve eaten something that contains tryptophan, and the carbs will help ferry the tryptophan from your bloodstream to your brain.

But Thanksgiving isn’t exactly about eating small, well-timed snacks. It’s more about heaps of mashed potatoes, mountains of stuffing, and generous globs of gravy—and that, along with alcohol, is more likely the reason you collapse into a spectacular food coma after your meal. Overeating (especially of foods high in fat) means your body has to work extra hard to digest everything. To get the job done, it redirects blood to the digestive system, leaving little energy for anything else. And since alcohol is a central nervous system depressant, it also slows down your brain and other organs.

In short, you can still hold turkey responsible for your Thanksgiving exhaustion, but you should make sure it knows it can share the blame with the mac and cheese, spiked apple cider, and that second piece of pumpkin pie.

[h/t WebMD]