Glue thumb|upright=3|Preparing casein glue Casein-based glues are formulated from casein, water, and alkalis (usually a mix of hydrated lime and sodium hydroxide). Milk is skimmed to remove the fat, then the milk is soured so that the casein is precipitated as milk curd. The curd is washed (removing the whey), and then the curd is pressed to squeeze out the water (it may even be dried to a powder). The casein is mixed with alkali (usually both sodium and calcium hydroxide) to make glue. Glues made with different mixes of alkalis have different properties. Preservatives may also be added.
Glue thumb|upright=3|Preparing casein glue Casein-based glues are formulated from casein water and alkalis (usually a mix of hydrated lime and sodium hydroxide) Milk is skimmed to remove the fat then the milk is soured so that the casein is precipitated as milk curd The curd is washed (removing the whey) and then the curd is pressed to squeeze out the water (it may even be dried to a powder) The casein is mixed with alkali (usually both sodium and calcium hydroxide) to make glue Glues made with different mixes of alkalis have different properties Preservatives may also be added