Casein glue is made from milk protein. It is known to have a moderately high strength and has a high water resistance. You can buy the glue in a retail setting or produce it at home. Casein glue is better than hide glue, as it has a better moisture resistance.
The downside to casein glue is that it does have a short pot life, but does allow you enough time to set your pieces into place. Also it does tend to stain woods rich in tamic acid, such as oaks. The glue as well has a higher blunting effect on tools and can dull them quickly. Lastly, casein glue can be attacked by mold and fungi.
Below is a recipe to make casein glue at home.
- Skim Milk powder
- White vinegar
- Baking Soda
- Dilute the skim milk powder, as per the packets directions, to make a 100ml of skim milk.
- Put milk into a pot and add 15ml of vinegar
- Gently heat the mixture till the skim milk curdles. Do not heat for too long as it can ruin the glue.
- Filter the liquid through a paper filter and wash the curds to remove as much of the vinegar as possible.
- Add a 1/2 teaspoon of baking soda to the curds and carefully stir with a small flat stick.
- Add water one drop at a time till a glue like texture is achieved.
If you would like to create casein powder stop following the directions after you wash the curds. Instead of adding the baking soda, press the curds to remove all the moisture you can. Set out the casein to dry. Once it is dry reduce it to a powder and store it in a dry area. When you are ready to use the glue add water to the powder till a glue like texture is created.
*Skim milk is the best choice to make casein glue, as fattier milks will produce a weaker glue.