Definition: Cannon fuse is typically a 2-3mm diameter cord with a black powder core. There are three external layers to visco fuse. First, a layer of string is wound around the core, then a second, less tight layer of string is wound in the opposite direction to prevent unraveling. The last layer is a low-nitrate nitrocellulose lacquer that keeps the fuse from falling apart. The last layer helps to make the visco fuse water resistant and to prevent moisture from degrading the black powder core. Unlike dynamite safety fuse, visco fuse burns with a visible external flame.