Non-hydraulic lime is a slower setting low cost alternative to hydraulic lime. Whereas hydraulic lime sets by hydrolysis (chemical reaction with water), non-hydraulic lime, also known as 'air lime', sets by carbonation. It needs air to carbonate and thus set. Unlike hydraulic lime, which is powder derived from lime stone containing impurities, non-hydraulic lime is drawn from pure calcium lime stone and turned into a putty through a process of high temperature heating, slaking, and maturing.
