Milk paint has been around for centuries and was used in cave paintings. It is made of simple, non-toxic ingredients which makes it a popular choice for people who want to live "green." The popularity has waxed and waned throughout the years due to certain features of the paint, like its composition and transportability.
There is no known date for when milk paint was invented, but we know that ancient people used it. Analysis of cave paintings has shown that the paint is very similar to the milk paint people now use in their homes. Also, the paint on King Tutankhamen's coffin was made with milk.
Milk paint is made of lime, skim milk (or just casein, a protein found in milk that adheres to lime) and pigment. Milk paint is available at hardware stores from various companies, or you can make it yourself. When making it yourself, continue adding pigment until you get the desired color. When you buy milk paint it normally comes in powder form and requires you adding water.
Milk paint was used to paint structures all throughout colonial America. However, during the Renaissance period Jan van Eyck developed a type of oil paint that because widely used, but milk paint still remained popular. Then in 1868 the paint can was invented so paint could be transported. This made milk paint lessen in popularity because thanks to its milk base, it could go bad before it reached the user. As people began to be more environmentally conscious in recent years, milk paint regained popularity for its natural aspects.
The obvious advantage of milk paint is that it is not harmful to the environment. All the materials used are natural so there are no harmful fumes emitted into the air. Making your own milk paint gives you control over the shade of color that you get.
One disadvantage to using milk paint is that the materials are not water resistant. In order to make something painted with milk paint waterproof, it needs to have a final varnish on it. The final color that appears on the painted object may slightly vary, because milk paint adheres to different materials in different ways.