Quicklime is made by putting limestone in a furnace while wearing gloves. If the player isn't wearing gloves, the limestone will just explode and damage them. Quicklime is used in the Regicide quest for making the barrel bomb.
With an empty pot in inventory, the quicklime is used with a pestle and mortar to make a Pot of quicklime.
Limestone can be mined east of Varrock (near the house of the Odd Old Man) and in north-east Tirannwn.
Trivia
- Historically, quicklime was used at military by Ottoman Empire in the late 17th century, later in by the other nations throughout the 18th century. It was mixed with water and smeared on 8 feet tall bandages made of linen. Then, the bandages were wrapped up and become a quicklimy ball. The projectile later set to fire and fired from a mortar. The shot would cause a fire where it fell which could not be extinguished by water and caused burns on the skin, as well as permanent blindness if it hit the eyes. It also made breathing impossible.