Can You Write on a Hard-Boiled Egg Before You Peel It?

Maybe it’s my eggs.

A dozen boiled eggs with lion marks visible in...

A dozen boiled eggs with lion marks visible in a saucepan. (Photo credit: Wikipedia)

Maybe it’s because they are brown.

Maybe it’s because they are fresh from the farmer.

I’ve found eggs take a lot longer to boil when they are really fresh, something I learned when we kept chickens in our front yard for about eight years.

So, the shells of very fresh eggs might be too strong for this experiment.

Whatever it is, I could not get today’s experiment to work.

Do You Test All Your Experiments?

I test about three-quarters of the experiments I write about.

I look for activities that will be fun with and for grandchildren that meet several criteria:

  • They are fun
  • They take 5-10 minutes to complete
  • You can do them with materials you are likely to have around the house
  • They have some educational underpinning
  • Instructions are clear and precise.

If it is something simple, like lining up buttons in a pattern or stacking sugar cubes, I do not do it myself. I just write about it.

If, however, I’m not sure if it will work as described, I try it out myself.

If it doesn’t work, I look up the concept on the Internet to see if anyone else has a different way that might work.

If not, I abandon the activity and look for something else.

Freezing water instantly turned out to take a special chemical that only a few sites mentioned. It was not a chemical you would likely have around your house.

Getting an oatmeal box to roll with weights suspended inside just never worked.

Back To The Eggs and Invisible Writing

This time, I’m writing about it because I think the idea is really cool.

I challenge my readers to tell me if they’ve ever tried it, if it worked and what kind of eggs they used.

Here are the three ways I tried, the first from 

Equal Parts Alum and White Vinegar/Boil Egg First


  • Small bowl
  • Measuring cup
  • Alum
  • White vinegar
  • Q-tips cotton swabs
  • Hard-boiled egg


  • Dissolve one part alum in one part vinegar. I used 1 tablespoon of each.
  • Mix alum and vinegar well.
  • Dip one of the Q-tips in the alum-vinegar solution.
  • Write something on the eggshell with the wet Q-tip.
  • Let the alum-vinegar solution dry on the eggshell.
  • Peel the egg.

What Should Happen?

The vinegar should dissolve some of the eggshell, allowing the alum through to mark the egg white inside with your message.

I got nothing, no secret message, but the egg was delicious.

Bizarrelabs described the experiment and said sometimes it didn’t work. 

Next: Diluted Alum and White Vinegar/Boil Egg First gave a different ratio for the alum and vinegar.


  • Hard-cooked egg
  • 1 Tablespoon alum
  • 2 cups white vinegar
  • Fine-tipped paintbrush, toothpick or Q-tip.


  • Hard boil egg; allow to cool
  • Stir alum into vinegar.
  • Dip brush, toothpick or Q-tip into the solution and write on the egg
  • When the egg is later peeled, the message will appear.

This site had the same explanation of what is supposed to be happening.

The vinegar dissolves the calcium carbonate in the eggshell, allowing the alum to go through (permeate) the shell and discolor the egg white.

It also did not work.

This site also said you should not eat the egg because alum is no longer considered safe for pickling.

It used to be a common ingredient for pickling and that is why you will find  it in the baking section of the grocery store, with other spices.

The site says alum is still approved as a food additive by FDA.

But, it can be dangerous in amounts over an ounce and should not be inhaled. It is slowly being withdrawn from use.

Write Before Boiling

Two sites said to write the secret message before hard boiling the eggs.

The Milwaukee-Wisconsin Journal Sentinel reprinted a suggestion one of their readers sent in.

Using the same diluted alum and vinegar solution to paint on the egg, they suggest waiting several hours after painting the message before boiling the egg.

I waited about two hours. No luck.

The Little Giant Encyclopedia of Card & Magic Tricks, excerpted in Google books, says to write the name of a card on the egg with the diluted alum-vinegar solution, then boil the egg.

Then, arrange to have someone pick that card out of a deck through a magic trick explained elsewhere in the book, crack open the egg and reveal the name of the card they are holding.

Now, that would be an impressive trick.

Have you ever heard of this secret message inside an egg trick?

Have you ever tried it?

What kind of eggs did you use?

 To you and sharing magic with your grandchildren.


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Carol Covin, Granny-Guru

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