Non-flexible collodion originally was used to create artifical "scabs" to seal wounds on the battlefield. It later became an invaluable makeup tool for stage actors and film artists such as Lon Chaney, who frequently used collodion to alter his features. As the name suggests, however, non-flexible collodion is not very flexible. Due to the massive injuries around the Joker's mouth, performers who use collodion to approximate the scar effects will find their movements somewhat restricted. (Try one of those insane, gape-mouthed Joker laughs, and it'll likely hurt for a hot minute.) Still, Collodion is great for hi-res/hi-def photography work, on account of its realism. It never looks fake. It's also a lot quicker, cheaper, and easier to apply than most other techniques. If you're looking for extreme realism on a tight budget, collodion is hard to beat. Collodion scars may be gently peeled off (take care not to tear the skin), or more easily removed with acetone-based nail polish remover.