Things You'll Need
10 tbsp. skim milk
Medium sized cooking pot
2 tbsp. white vinegar
1 tbsp. baking soda
Casein is a protein found in milk and has been used for centuries as the main binding ingredient in glue. Due to the popularity of synthetic glues, casein glue is not used as commonly today as it once was. Its ability to resist moisture makes it popular for woodworking and it is also is used to help paints and coatings adhere more strongly to surfaces. You can make homemade casein glue from skim milk, which is heated and combined with other ingredients to separate the curds, which are then made into the glue.
Pour 10 tbsp. skim milk into a medium sized cooking pot. Do not use any other type of milk besides skim cow's milk.
Heat the skim milk on a medium or low setting for three to five minutes. Do not allow the milk to reach a boil.
Add 2 tbsp. white vinegar to the milk. Stirring constantly, allow the vinegar and milk solution to remain on the heat until the milk separates into curds, which are the solid pieces, and whey, the liquid. As soon as the milk curdles, remove the pot from the heat.
Allow the mixture to cool and pour it into a piece of cheesecloth.
Squeeze the cheesecloth over a bowl until all of the liquids are removed. Keep the curds inside the cheesecloth and discard the whey.
Rinse the curds well to remove any traces of vinegar. Pour the curds into a bowl and add 1 tbsp. baking soda. Stir the baking soda and curds together until they are well incorporated and reach a glue-like consistency.
Apply the casein glue to any woodworking or paper projects.