Santeria's standard practice is to use crushed eggshells to draw crucifixes on objects, including one's own body, that require shielding from negative energy. Usually, these symbols are drawn around any house's entry portals like doors, windows, and even vents. This action will guard against antagonistic forces and blockade immaterial creatures, harmless ones included, that could otherwise gain access.
In powdered form, egg shells or cascarilla are used to safeguard the home, and the powder is sprinkled on the floor or blended with water or floor cleaner then applied to the floors. Crushed eggshells are used for dusting the entire body for protection. It is used to dust hands in case of contact with anything evil.
It can also be put into a bath to drive out antagonistic forces built up over time from unfriendly encounters. When bathing, douse the entire body with the water three times. This rids the body of negativity and purifies so other rituals have a chance of success.