Turn Milk Into Plastic

Your Challenge: Turn milk into plastic using everyday household items! Milk splashing into a glass





Microwavable container


Paper Towels



Here’s How:

  1. Heat one cup of milk in the microwavable container. Heat on 50% power for 5 min. The milk should be at hot chocolate temperature. If the milk is not hot enough after 5 min, repeat heating in 2 min intervals until ready.
  1. Add 4 tablespoons of vinegar to the mug. Carefully add the hot milk to mug and begin stirring. Curds will begin to form immediately.
  1. Layer paper towels, 5 to 6 sheets thick, upon a surface that may become damp.
  1. Spoon the curds from the mug, while draining the excess liquid in the sink. Press additional papers towels on the curds to remove liquid. This is Casein Plastic.
  1. Begin kneading and molding the plastic into various shapes and figures. The plastic will need to sit for 48 hours until fully hard and dry.


Take it Further:

Add glitter or food coloring to the wet curds to create different colored shapes. Use cookie cutter or other molds to help mold the shapes.


How It Works:

Plastics are all similar, containing molecules that are repeated over and over again into a chain called polymers. Milk contains molecules of a protein called casein. When milk is added to an acid, such as vinegar, the pH of the milk changes. The pH change causes the casein molecules to unfold and reorganize into long chains, curdling the milk. The curds can then be kneaded and molded as casein plastic.


Fun Facts:

  • Casein plastic is commonly used to make fountain pens!
  • Casein plastic is extremely environmentally friendly, because it will decompose over time, unlike plastics made from petroleum products.
  • The National Plastic’s CenterMuseum, located in Leominster, MA, hosts exhibits about the history, manufacturing, and recycling of plastics!
  •  Companies are beginning to research and develop ways to manufacture plastic from renewable resources, such as plants. Chemists at Pacific Northwest National Laboratory have been studying how to use glucose as fuels, plastics, and other petroleum products.
  • Casein plastic was first manufactured in London in 1900. It was used to make jewelry and buttons. Today, there are thousands of Casein jewelry collectors around the world!


Related Careers:

Chemist,  Conservation Scientist, Geoscientist

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