Rigid Collodion – How To Scar, also called “Scarring Liquid”, is a viscous, yellowish substance widely used in theatrical makeup special effects to simulate shapes of wounds and scars.
It’s particularly popular for rendering The Joker cheek scars.
It works by wrinkling the skin as it dries, leaving a puked area very similar to healed scars. Colors can also be used to simulate a fresh wound. It’s usually applied with a brush in multiple coatings, each subsequent layer reinforcing the effect by deepening the scar.