Setting of plaster of paris involves

The setting of plaster of Paris takes place by hydration due to the formation of a solid crystalline hydrate and hardening of Plaster of Paris is hydration reaction, which is reverse of the dehydration of gypsum. Plaster of Paris quickly sets to a hard mass when made into a thin paste with water. A slight expansion takes place in the process and heat is evolved. This process is exothermic.