1. Burning of impure limestone / kankar containing clay containing less than 30 %. With coal or charcoal as fuel. 2. If soft limestone is used, it is powdered, mixed with clay in right proportion & burnt in kiln. 3. If hard limestone is used, It is burnt &slaked first, mixed with clay and then reburnt. 4. The product on canclination is slaked with water or ground into powder for use in construction. 5. Hydraulic lime slaked with difficulty, therefor lumps of hydraulic lime should be ground before slaking. (time required @ 12 – 48 hrs.) 6. Hydraulic lime is kept in sacks without injury as long as it is protected from air & moisture. After slaking it should be used within a week.