Plastic Milk

You can consider this experiment as making plastic from milk, or making cheese, depending on how you treat it.

What you need:

• milk, heated to almost boiling
• vinegar
• sieve or strainer
• cloth

What to do:

1. Heat 1 cup of milk up so it is simmering. Take it off the heat and pour it into a bowl.
2. Add 4 tablespoons of vinegar to the milk.
3. Stir the mixture. It will become lumpy as the liquids separate from the solids.
4. Strain your mixture through a cloth over a sieve. The liquids will go through and you will collect the solids in the cloth.
5. Rinse the solids with water, the squeeze it to remove the water.
6. You can eat it now – it’s cheese – or make it into a shape, such as a ball, and leave it to dry for a few days.

What happens:

When you add the vinegar to the milk, a protein in the milk (called casein) won’t mix with the vinegar, so it separates out, becoming a solid. When the casein dries, it feels a little like plastic. If you roll the casein into a ball and let it dry, it will be like a plastic ball.