• Skip to primary navigation
  • Skip to main content
  • Skip to footer
Zippy Facts Logo

Zippy Facts

Interesting Random Facts

  • Animals
  • Culture
  • Firsts
  • Food
  • Geography
  • Health
  • History
  • Inventions
  • Language
  • Mythology
  • Odds
  • People
  • Religion
  • Science
  • Space
  • Universe
  • World
You are here: Home / Science / Why are Fresh Hard Boiled Eggs harder to peel and How do you make them easier to peel?

Why are Fresh Hard Boiled Eggs harder to peel and How do you make them easier to peel?

July 4, 2020 by Karen Hill

When the eggs are done, cool them down quickly in cold running water. That shrinks the albumen away from the shell somewhat and makes an egg easier to peel.

It also keeps the yolks from turning green. Very fresh eggs are harder to peel because the albumen tends to stick to the membrane on the inside of the shell. But after several days the membrane retreats and the sticking tendency diminishes, so don’t hard-cook your freshest ones.

By the way, after you hard-cook eggs, keep them refrigerated. It’s easiest if you put them right back in the carton containing your uncooked eggs. But how do you tell the cooked ones from the raw? Easy. Put an egg on the counter and give it a spin. If it resists spinning, it’s uncooked, but if it spins like a top, it’s hard. The effect is most noticeable if you spin the eggs on their larger ends.

Or you could just pencil an H on the shell of each hard one, but where’s the fun in that?

The yolk and white in an uncooked egg are liquid and free to slosh around slightly inside the shell. When you twist the egg fast in an attempt to spin it, the contents resist moving. That is, the contents have inertia, a desire to stay motionless until pushed by some force or other. That’s Newton’s First Law of Motion: an egg yolk at rest will remain at rest until shoved by something harder than raw egg white. Those weren’t his exact words.

When you apply a twisting force to the outside of the egg, the force isn’t transmitted effectively through the egg white; it’s like trying to play pool with a liquid cue. The egg’s contents try to stay motionless and lag behind. In effect, some of your twisting force is wasted and the egg won’t spin as much as you might expect from how hard you twisted it. In a hard egg, on the other hand, the solid contents transmit your force to the whole egg mass, and the egg spins with the full amount of momentum you expect.

Want some more fun with egg physics? If you spin the egg on its wide end rather than on its side, it will spin faster. The reason is the same as for an ice skater who spins faster as soon as she pulls her arms and legs in closer to her body (closer to her spin axis). Her body’s spin momentum (or angular momentum) is proportional to both her spin speed (her angular velocity) and the average distance of her body parts from the spin axis (her average spin radius).

Her total momentum must remain constant (that is, angular momentum is conserved), so if she decreases her spin radius by pulling in her limbs, her spin velocity must go up. In the case of the egg, the spin radius is smaller when you spin it on its end rather than on its side, so it spins faster.

Related Facts

  • Does It Ever Really Get Hot Enough To Fry an Egg On the Sidewalk?
  • Why Are You Supposed To Store Eggs Small End Down and How Does It Keep Eggs Fresh Longer?
  • Why Do Guns Fire Spinning Bullets and What Is Angular Momentum?
  • How are Eggs Graded and How many Different Types of Eggs are there according to the USDA?
  • Where does Salmonella come from and How does Salmonella Bacteria spread?
  • How Long Does It Take For Eggs To Go Bad and How Do Eggs Turn Rotten?

Filed Under: Science

About Karen Hill

Karen Hill is a freelance writer, editor, and columnist. Born in New York, her work has appeared in the Examiner, Yahoo News, Buzzfeed, among others.

Previous Post: « How does adding salt to the water before boiling eggs prevent the eggshells from cracking?
Next Post: What causes the greenish black, grey color of hard boiled egg yolks and Are they safe to eat? »

Footer

Follow

  • Facebook
  • Flickr
  • GitHub
  • Google+
  • Instagram
  • LinkedIn
  • Medium
  • Pinterest
  • StumbleUpon
  • Tumblr
  • Twitter
  • YouTube

Categories

Accomplishments Animals Culture Firsts Food Geography Health History Inventions Language Mythology Odds People Religion Science Space Universe World Your Body

About

Zippy Facts empowers the world by serving educational content that is accessible to everyone.

A tribute to growing up, zippyfacts.com showcases interesting and unusual facts about the world.

Our mission is to use technology to facilitate knowledge transfer and sharing.

Copyright © 2020 Zippy Facts

  • About Us
  • Contact
  • Privacy Policy