You don't need any special skills to make strong homemade glues. Protein-based glues are durable and water-resistant. One type is casein glue, or milk glue, which can permanently bond porous materials like wood and paper. Casein glue has been used since antiquity; the Ancient Egyptians used it as an adhesive and paint medium. Another protein-based glue you can make at home is gelatin glue, also known as glass glue because of its ability to bond smooth surfaces such as glass and metal.
Pour one pint of skimmed milk into a saucepan and place it on a stove or hotplate at a moderate heat. When the milk is hot -- but not boiling -- slowly add 6 tbsp white vinegar, stirring continuously with the spoon or spatula. The milk will begin to separate. When this happens, remove the pan from the heat.
Stir the milk until all the solid curds separate from the liquid whey. Cool the pan until all the curds settle on the bottom.
Place the filter or towel in the funnel and set the funnel in a container large enough to support the funnel and hold all the fluid from the pan. Carefully pour the curds and whey into the funnel to separate the solids from the liquids. Gently press and squeeze the curds of casein inside the filter to remove the excess liquid.
Mix the baking soda with the water and pour onto the casein. If there is any acid left, the baking soda will neutralise it. The acid is completely neutralised when the mixture stops frothing.
Place the casein glue into the jar. You can now use it for glue. Store it in the refrigerator for a few days.
Pour 2 tbsp of cold water into a bowl. Sprinkle two packets of plain unflavored gelatin onto the surface of the water. Set the bowl aside and wait for the mixture to soften; the powdered gelatin soaks up the water to form a gel.
Heat 3 tbsp of skimmed milk to boiling. Stir into the gelatin using a spoon or spatula, completely mixing the milk and gelatin. Add a few drops of the essential oil to the mixture as a preservative; stir into the gelatin with the spoon or spatula to blend well.
Apply the glue with a brush to the surfaces to be glued and press them together. Use this glue to stick paper, glass, metals, wood and other materials. If you are gluing curved objects such as marbles or glass nuggets, allow the glue to set slightly before you use it.
Make casein glue even stronger by mixing it with a strong alkali such as ammonia, borax or slaked lime.
Although water-resistant, these glues are not completely waterproof. They may deteriorate if left in humid or wet locations.