The mineral was used in Egyptian mummification because it absorbs water and was a drying agent. Also, when exposed to moisture the carbonate in natron increases pH, which makes a good environment for bacteria. In some cultures, natron was thought to keep both the living and the dead spiritually safe. Natron was added to castor oil to make a smokeless fuel, which allowed Egyptian artisans to paint artworks inside ancient tombs without staining them with soot.