Thursday, February 14, 2013

The Rubber Egg: Science for Kids in the Kitchen

The three women who raised me all had their own special recipes for the children in their home. These were not recipes for eating but ones for playing. As I think about it now I am surprised and very grateful for the effort put into making playtime supplies instead of just going out and buying similar toys or commercialized substitutes.

Now that I am a father with four children of my own I find myself recalling the fun and imagination these recipes brought me and I want to pass the experience on to my little ones. So I have decided to revisit the recipes (or experiments) shared with me as a child while researching some new kitchen science to pass on to you. This is not in the normal scope of this blog, but it has been so much fun!

The Rubber Egg 

Soaking a hard boiled in distilled kitchen vinegar will dissolve its shell leaving the boiled egg rubbery enough to be bounced on the floor like a ball. This recipe also works for making rubber chicken bones as well.

Day 2: Shell appears to
be corroding away.
1 hard boiled egg.
1 glass jar, large enough to hold the egg with enough vinegar to cover your egg(s).
Vinegar, distilled white or cider work best.

Method for turning an egg into a bouncy ball:
1. Place your egg(s) into your glass jar.
2. Add vinegar until egg(s) are completely covered.

Science Alert: At this time you will be able to take notes on what is happening to your egg(s). Do you notice little bubbles accumulating on your egg(s) and fizzing off? The acetic acid of the vinegar is eating away at the calcium carbonate in the eggshell. In time not only will the shell loose its structure but the color may change too! Keep checking on it.

3. After 3 days it is time to remove your egg(s). After you remove them from the vinegar rinse them under running water.
4. Gently squeeze your egg(s). Notice the feel. Now give your egg(s) a bounce on a hard surface like the counter or the floor. Does it bounce? How high can it bounce?
Day 3: Rinsed and ready to bounce?

On our rubber egg journey we made made two minor changes to the above recipe; a brown shelled egg and red wine vinegar. So as you view the pictures I have included note that our egg was stained as it was transforming in the red wine vinegar. The rest of the recipe was followed exactly.

Now about the results. I had visions of a high bouncing egg ricocheting off the walls endangering a vase of flowers. This was not the case. The egg has transformed into more than just hard boiled and it is rubbery and toddler durable passing a 15 minute play session with my youngest son. A simple hard boiled egg would have ruptured upon impact and definitely been crumbled in the hands of a 2 year old. Thankfully our two dogs never got a hold of it as I am sure it would have made them sick. Once again I had great expectations for the end result although the whole scientific process and entertainment value was worth the egg, vinegar and time. Anticipation can really stir the imagination.

Initiating Rubber Egg & Elliott Test.
In all of the rubber egg experiments I have researched not one of them has commented on what to do with the egg past testing it's ability to bounce. I myself never questioned if there could be more to this experiment. Well not until later in the day when I picked up the rubber egg which had been abandoned on our kitchen counter. The obvious was happening: dehydration. It was this observation and the appearance of the egg which began to fill my imagination with the curiosity of what would be the next phase to this scientific exercise.

Right now. Later in the evening of day 3 it is too soon to say. Time, once again will make us wait to see what will become of the rubber egg. I may not ever reveal to you what ultimately happens as the transformation continues. The question is will you and your children find out for yourselves?

Much later in Day 3: The once smooth exterior
of our egg has developed  a leathery skin.
What will come next?


  1. You've been hit with a Liebster Award! Woohoo for you! The rules are on my blog to pass it along!

  2. Hi Graham, been meaning to pop in for ages - finally here! I've picked this post to comment on because I intend to do this with my kids this week. We homeschool and it should be pretty fun for the younger 2. Don't tell me what happened, let us find out!

    1. Hi LinsFood,

      Glad you will be joining us on this journey!

      I promise not to tell you what has happened to the egg. However I will tell you that we still have it hanging around in the kitchen.

      Is there no end?