how to make bioplastic (from milk)

how to make bioplastic (from milk)

What’s a bioplastic?

A bioplastic is a "plastic" made from renewable and organic sources like biopolymers derived from plants.

Types of bioplastics:

starch based

cellulose plastics

PLA plastics (not as biodegradable)

What is milk plastic?


Milk plastic, also known as casein plastic, is a type of plastic that was invented in the early 20th century. It is made by mixing casein, a protein found in milk, with an alkaline substance such as lime or ammonia. The mixture is then heated and pressed into a mold to form a solid shape.

Casein plastic was particularly attractive as a substitute because it could be molded and shaped in much the same way as natural materials. It was also relatively inexpensive to produce, especially compared to rare and exotic materials like ivory.  It  was becoming scarce and expensive. It was used to make a variety of items, such as buttons, buckles, and combs In addition, it was more durable and resistant to moisture than many other synthetic materials of the time, making it suitable for a variety of applications.

During World War II, casein plastic became even more important as a material, as traditional sources of raw materials became scarce due to the demands of the war effort. Milk plastic was used to make a wide range of items, including buttons, buckles, and other small parts for military equipment.

While milk plastic was once a popular material, it has largely been replaced by other types of plastics that are cheaper and easier to produce. However, it is still sometimes used in niche applications, such as in the production of high-end buttons or in the restoration of historic items made from milk plastic.

Here's a general recipe for making milk plastic:

Watch a tutorial here


1 cup of milk

4 teaspoons of white vinegar or lemon juice

1 tablespoon of baking soda



  • Heat the milk in a saucepan until it is almost boiling.
  • Remove the milk from the heat and add the vinegar or lemon juice. Stir until the milk curdles and separates into solids (the casein) and liquid (the whey).
  • Strain the solids through a cheesecloth or a fine mesh sieve to remove as much of the liquid as possible.
  • Add the baking soda to the solids and knead them together with your hands until they form a pliable dough-like substance. If the mixture is too dry, you can add small amounts of water until it reaches the desired consistency.
  • Roll the mixture into a ball and press it into a mold or shape it into the desired form.
  • Let the milk plastic dry completely, which may take a few days, depending on the size and thickness of the object.
  • Sand and polish the milk plastic to smooth out any rough edges or imperfections.
  • Note: This recipe is just a basic guideline and the proportions can be adjusted based on the desired result. Additionally, other additives such as glycerin or oils can be added to improve the pliability and durability of the milk plastic.