Earth-friendly and kid-friendly science, make milk plastic!  This is the perfect simple science experiment  for any time of the year including Earth Day!  Kids will be amazed by the transformation of a couple of household ingredients into a moldable, durable piece of a plastic-like substance. This milk and vinegar plastic experiment is a terrific example of kitchen science, a chemical reaction between two substances to form a new substance.

Make milk plastic with this milk and vinegar plastic experiment for kids. Earth day science and simple STEM activity that uses everyday supplies.Pin

Plastic Milk Demonstration

Add this quick and easy milk and vinegar experiment with just a few ingredients to your science lesson plans this season. If you want to learn what happens when you add vinegar to milk, let’s dig in and explore the chemistry of curds!  While you’re at it, make sure to check out these other fun chemistry activities.

Our science activities and experiments are designed with you, the parent or teacher, in mind!  Easy to set up, quick to do, most activities will take only 15 to 30 minutes to complete and are heaps of fun!  Plus, our supplies lists usually contain only free or cheap materials you can source from home!

Milk and Vinegar Experiment

Let’s get right to learning how to turn milk into a plastic like substance… Head to the kitchen, open the fridge and grab the milk.

This milk and vinegar experiment asks the question:  What happens when you add vinegar to milk?

Chemistry Science Fair Projects

Find tips for changing the variables with this plastic milk science demonstration to create an experiment after the activity below.

Science projects are an excellent tool for older kids to show what they know about science! Plus, they can be used in various environments, including classrooms, homeschool, and groups.

Kids can take everything they have learned about using the scientific method, stating a hypothesis, choosing variables, and analyzing and presenting data.

Want to turn one of these fun chemistry experiments into a science project? Then you will want to check out these helpful resources.

FREE Chemistry Activity Guide

Grab this free chemistry guide to our favorite science activities for kids to try!

Watch the Video!

You Will Need:

  • 1 cup milk
  • 4 tablespoons white vinegar
  • Sharpies
  • Cookie cutters
  • Strainer
  • spoons
  • Paper towels

How to Make Plastic Milk:

STEP 1: Add 1 cup of milk to a microwave safe bowl and heat for 90 seconds.


STEP 2: Mix in 4 tablespoons of vinegar and stir for 60 seconds.


Stirring slowly, you’ll notice that solid chunks called curds start to form and separate from the liquid called whey.


STEP 3: Pour the mixture into a strainer and press out all the liquid leaving just the solid clumps or curds behind. This will resemble the consistency of ricotta cheese!

STEP 4: Press the paper towel into the strainer to soak up any of the leftover liquid or whey and remove it.


STEP 5: Lay out a piece of paper towel, place a cookie cutter onto the paper towel, and press your vinegar-milk mixture or plastic dough into the cookie cutter and let set for 48 hours.


STEP 6: Wait the 48 hours and color with a Sharpie if desired!


Making Plastic Milk in the Classroom

You will want to set aside a couple of days for this science experiment since it will need to dry before it can be colored!

If you want to turn this into more of an experiment rather than an activity consider testing different fat percentages of milk such as fat-free and low-fat varieties. Additionally, you could test different ratios of vinegar to milk. Would another acid like lemon juice turn the milk into plastic?

What Happens When You Mix Milk and Vinegar

This milk and vinegar experiment does not produce real plastic.  The new substance is called casein plastic. Plastics are actually a group of different materials that may look and feel different but can be easily molded into different shapes. If you want to explore real plastic polymers, try some homemade slime!  Click here to read all about making homemade slime for easy science.

This plastic-like substance forms from a chemical reaction between the milk and vinegar mixture. When the molecules of a protein in the milk, called casein, comes in contact with the vinegar, the casein and vinegar do not mix. When the milk is heated, the casein molecules, each a monomer, unfold themselves, move around, join forces, and create a long chain of polymers, creating the casein plastic!

The casein molecules become these plastic-like blobs you can strain and mold into shapes. This is one way of making simple cheese from milk.

TIP: Remember that the milk might smell strong while experimenting with it!

More Fun Science Activities to Try

Naked Egg Experiment

Egg Drop Challenge

How To Make Oobleck

Skittles Experiment

Baking Soda Balloon Experiment

More Helpful Science Resources

Here are a few resources to help you introduce science more effectively to your kiddos or students and feel confident when presenting materials. You’ll find helpful free printables throughout.

Printable Science Projects For Kids

If you’re looking to grab all of the printable science projects in one convenient place plus exclusive worksheets, our Science Project Pack is what you need!

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