MEST · Projects

That’s One “MEST” Up Egg!

A STEM experiment just in time for Easter!  Ed and my son were watching a show on one of the history channels about spies a couple of years ago.  The story is about a prisoner who was being given hard boiled eggs by an outside source.  These eggs were special because they looked like normal everyday hard boiled eggs that the prisoner was eating.  However, once the prisoner peeled the eggs, there were secret messages written on the whites of the eggs.   How did they do this without the messages shown on the shell?  What kind of disappearing ink could permeate a shell?   When Ed started thinking back about this show, of course we checked the internet for sources so we could get right to setting up another cool stem experiment!

We are going to recreate this chemistry for our STEM project and turn it into an experiment!


  •  An AMC talk website gives a little historical background on stenography and concealing messages in eggs.
  • The Secret Behind the Secret Message Egg by the website ‘Instructables’.   This site did not have much luck with getting any messages to form.  They think it is a myth!  Hmm…they tried many ways, so we will have to see if we can even get it to work.  
  • The Secret Message Egg by the website ‘Egg Farmers of Alberta’.  This site gives the instructions how to write a hidden message on the egg.  This is what we followed to form an experiment.
  • How Does Calcium Carbonate React to Vinegar by

Supplies needed:

  • hard boiled eggs
  • alum (a spice found in the grocery store- we used McCormick’s)
  • white vinegar
  • paintbrush, toothpick, q-tip….or dipped calligraphy pen
  • spoon
  • drying stand for the eggs ( I realized we needed this halfway through the experiment;))

Our Procedure:

We hard boiled all the eggs the day before.  I let them sit out a half hour before the experiment so they weren’t super cold when we tried to do this.  The directions by the above source (Egg Farmers of Alberta) say to dissolve alum in vinegar (about 1 tbsp. to 2 cups of vinegar) and stir with a spoon.  With our experiment, we want to see what is the best ratio of alum to vinegar that yields the strongest and darkest message!  That is, if we can get a message at all!!  We tried all of these ratios and named them very special names.  My kids loved coming up with names from spy movies.  NOTE: As you can see we only changed the amount of alum and kept the liquid amount the same.

  1. BOB – 1/4tsp. alum to 1/4 cup vinegar
  2. ZODIAK- 1/2 tsp. alum to 1/4 cup vinegar
  3. JACK –  1 tsp. alum to 1/4 cup vinegar
  4. BOND- 1(1/4)tsp. alum to 1/4 cup vinegar
  5. INDI- 1/2 tbsp. alum to 1/4 cup vinegar
  6. BORNE- 1 tbsp. alum to 1/4 cup vinegar
6 cups with 6 different solution ratios


We labeled 6 cups with different names for each solution ratio.  On each egg we labeled the name with a sharpie first on the top and bottom.  If the name does not come through the shell with the solution or if it partially comes through, we will still know which solution was used because we labeled it with an actual sharpie pen.


We then dipped the calligraphy pen in the BOB solution and wrote BOB on the front of the egg.  We then dipped a paintbrush in the BOB solution and wrote BOB on the back of the egg.  This way we used both writing tools in case one was better to get that secret message to come through the shell.  We held the BOB egg as long as we could with our fingers on the top and bottom of the egg until the solution was dried.  Drying time for the egg was the part that I didn’t think about or prepare well for.  I should have had a drying stand for the eggs.  In either way, everyone got to hold an egg until it was pretty dry. ha!  We did this procedure on 7 eggs for each name that represented a different solution.  Once we were done with all of the eggs we put them in the refrigerator to wait over night.

NOTE: With younger kids I would use numbers instead of names.  Names were actually a lot harder for them to write with a paintbrush.  My daughter had more fun with the calligraphy pen but because the solution is hard to see and she had never used a dipping pen before it was a little tricky.  Although the spy names were fun, it would have been a little easier for them to have numbers to write with the solution.

The Science: 

The vinegar will dissolve the calcium carbonate in the shell of the egg.  This is similar to what happens when you leave an egg in vinegar.  The vinegar attacks the calcium carbonate and it completely dissolves the shell.    The alum will permeate the shell and leave the egg white discolored in those specific areas.

The Result:

Wow… not one egg had any markings the next day when we peeled them.    As we sat down together at the dinner table, we were asking ourselves….Is this a myth?…and hmm, maybe we shouldn’t be eating these? 😉   Ed and I decided to go with the nuclear option.  We got to thinking… if this egg stenography idea started in the 1500’s maybe vinegar wasn’t distilled back then.  Perhaps the POTENT raw apple cider vinegar (like BRAGGS with the mother) would be more acidic and have a better result in the experiment.  Perhaps that may be closer to the vinegar that they would have used?  That’s when we brought out the big guns…..of course we have that stuff stocked.


We named the solution AUSTIN= 1 tbsp. alum to 1/4 cup BRAGGS apple Cider Vinegar.  We dipped the calligraphy pen in the solution and on one side of the egg we wrote AUSTIN once.  On the other side of the egg we used the paintbrush and wrote AUSTIN more than one time.  We started thinking that if the experiment when you leave an egg in vinegar over night works to dissolve the shell, then maybe writing the name once is not enough.  The paintbrush was dipped in the solution and painted over and over 12 times in the same spot each time writing the name AUSTIN.  I held the egg all evening watching T.V. with the kids to dry each time.  haha…it was like high school again where you have to take the egg with you everywhere like a baby.  A very strange thing occurred.  The first time it was written it took forever to dry.  The more coats that were put on the shell, the faster it started drying like it was eating away at the shell quicker.  I stopped after 12 coats and it definitely looked a lot different than the previous procedure with the white vinegar.

We also noticed that you could see the name AUSTIN on the eggshell because of the tint of the apple cider vinegar.  So how would that have been a concealed message if you could see it on the outside of the shell.  Well, we put it to bed and refrigerated over night.  The next morning, we wiped the surface of the shell with a damp paper towel.  Now the eggshell cleaned up very nicely and there was no indication that we painted the word AUSTIN on the eggshell.  DRUMROLL please……time to peel!!!


BOOO……once again no markings!!!!!  WOW…I guess the alum has no purpose.  It didn’t seem to permeate the shell and discolor the egg whites.  The vinegar was definitely eating away at the shell, but why didn’t it work?  AUSTIN was a saturated solution with 1 tbsp. of alum to 1/4 cup vinegar.  We knew it was saturated because all of the alum was dissolved but at the very bottom of the cup there were still some particles.  HMMM…….We will still be thinking of this all through Easter!!!  Maybe we should have used natural farm eggs.  Our neighbors gave us some.  Perhaps the problem is the grocery store bought eggs?  If I can get this to work at all I will be sure to update this post.  But as for right now….I may have to agree with the author from INSTRUCTABLES.  DEBUNKED???? I hope you all have a better experiment with better results!  Please let me know, I would love to hear!!  One thing is for sure we now have 7 ways to NOT make a secret message egg! AND……..rather than one ‘MEST’ up egg, we got one ‘MEST’ up experiment!!!!!



Check out my other ‘MEST’ up project:

Some ‘Mest’ Up Weather!!



5 thoughts on “That’s One “MEST” Up Egg!

  1. This cracked me up…pun intended! I have never done this experiment so I don’t have a clue. But I wanted to commend you on your dedication to keep trying different ways to do it! Let me know if you end up figuring it out 🙂


  2. Now I know why you put vinegar in the dye solution for Easter eggs! I just wanted to say, I don’t know if Bragg ‘s vinegar is stronger because I thought most vinegar sold in grocery stores is diluted to the same % acidity. Not sure where you could get stronger acetic acid unless you know someone who works in a lab! Maybe the alum is not as potent as it was in medieval times. I am curious how it would react with the egg white without being visible through the eggshell. Maybe it would be different with brown eggs! I think this is a really neat experiment, and great that you do MEST/ STEM projects with your kids! Even though this didn’t work, they learned that science experiments don’t always produce the results you expect! : ) I just started poking around your blog and after reading just a few posts I am really impressed with your projects and ingenuity! Great job with all of it!


    1. Hi Linda, how are you? Thank you so much!! Yes poke around any time!!!! I know, isn’t this a fun project….it would have been really awesome if we could get it to work! That is true maybe the alum is what was stronger back then. How could I get my hands on some potent alum? ha. I am glad you liked the experiment….and yes I love incorporating ‘stem’ into their little worlds. As they get older maybe they won’t fear science and math. Thanks so much for checking my site out and commenting!! Let me know when you stop in again:) Talk soon!


  3. Hi Kathleen! I’m doing well, how are you? I work in the biology department of a community college, so I agree, the more STEM early on, the better! This egg thing intrigued me so much that I just spent an hour or two online trying to find out more. I learned: 1. There is a way to put a tiny note in a raw egg after soaking it in vinegar. 2. Alum is a good invisible ink on paper or cotton. 3. This formula was first published in a book about magic from the Middle Ages, and the modern-day guy who tried it out couldn’t get it to work and decided the author either deliberately left out some steps or didn’t really test it out before including it in his book. So maybe it is a hoax! : )


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