Sugar glass (also called candy glass, edible glass, and breakaway glass) is a brittle transparent form of sugar used to simulate glass in movies, photographs and plays. It is much less likely to cause injuries than real glass, and it easily breaks convincingly, making it an excellent choice for stunts. Sugar glass is also used to make sugar sculptures. Because sugar glass is hygroscopic, it must be used soon after preparation, or it will soften and lose its brittle quality.
Sugar glass is made by dissolving sugar in water and heating it to at least the "hard crack" stage (approx. 150 °C / 300 °F) in the candy making process. Glucose or corn syrup is used to prevent the sugar from recrystallizing, by getting in the way of the sugar molecules forming crystals. Cream of tartar also helps by turning the sugar into glucose and fructose.
Sugar glass is rarely used for stunt work in current times, as it is extremely fragile, and has been replaced with certain synthetic resins such as Piccotex.