Separating Milk to make a Polymer


Milk is made of many different molecules.  When the protein casein is separated out it can be molded to form a plastic-like polymer.


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  • Glass beaker

  • Paper towel

  • Erlenmeyer flask

  • Alcohol burner + stand + lighter

  • Thermometer in rubber stopper


1. In Erlenmeyer flask, heat milk until 60 degrees Celsius (~7 min). Remove from heat.

2. In Erlenmeyer flask, pour in vinegar and swirl   contents together and leave for 5 minutes.

3. In glass beaker, place paper towel flat on top of beaker opening and pour milk into beaker using the paper towel as a strainer.

4. Let milk drip into glass.  This may take about 20 minutes.

5. Use the Nuffield spatula to scoop up milk polymer into your hand.

6. Shape and let dry.

The Science Behind the Reaction

By adding vinegar to milk, it made it acidic. Casein, the main protein in milk, is not soluble in acidic conditions and thus separates out. Casein is made of long polymer strings just like plastic.

Keep Experimenting!

To make a glue with your milk polymer

1. Place the ball into a clean beaker and add 10mL of water and 15mL of baking soda.


2. Heat the beaker on your alcohol lamp and tripod until it starts to bubble.


3. Add more water and baking soda o get a thick cream consistency.


4. Wait till glue has reached room temperature before use.