Tuesday, December 18, 2012

The Plastic Milk Experiment

It's science experiment time!  A week or so ago we had some free time on the weekend to complete 3 science experiments.  The first one I'm sharing is titled "The Plastic Milk Experiment".  Of the 3, this was the one I thought was the coolest!  I learned about this experiment from Science Bob's list of experiments.  As the name suggests, the goal is to turn liquid milk into a "plastic".  It's a very simple experiment that requires the following:

1 cup of milk
4 teaspoons of white vinegar.

That's it!

Supplies for the Plastic Milk Experiment.

Take a cup of milk and pour it into a small bowl.  Heat the milk in a microwave until just before it boils.  Using cold milk will NOT work.  Then pour in the 4 teaspoons of white vinegar.  Gently stir the mixture and you should notice something weird happening.  The "white" part of the milk will start to clump together.


When the clump starts to form, dump the mixture into a strainer.  The solid clump will be left.  Go ahead and touch it and shape it into any shape you wish.  We stuck with a ball shape.

What is this?

After shaping the clump, put it on a plate to harden for a day.

A ball of milk!

Don't worry, it won't stink up the room.  After a day, the clump will harden and you now have "plastic" milk!  It's not really plastic, but resembles plastic.  So what's going on here?  Well, here's what Science Bob has to say about this:

"Plastic? In milk? Well, sort of. You made a substance called CASEIN. It's from the latin word meaning "cheese." CasEin occurs when the protien in the milk meets the acid in the vinegar. The casein in milk does not mix with the acid and so it forms blobs. True plastics, called poymers, are a little different."

This is an awesome experiment that's quick, requires few supplies, is easy to do, and is sure to get a positive reaction from your child.  


  1. Thanks for the easy father & daughter experiment, but don't forget to remind everyone to use warm milk. After a couple of failed tries with refrigerated milk and one very impatient daughter, I noted that Science Bob specified microwaving the milk. As a former lab rat myself, I should have been quick to realize that the reaction would be better served at higher temperatures.

  2. Thanks so much for this reminder. I did not realize I left out the part about heating the milk until just the other day. I was repeating this experiment for my niece and nephew and couldn't figure out why it didn't work. I was using cold milk, not warm/hot milk! Your comment reminded me to update this blog entry. It's now updated!