Visco fuse

[1] It is most commonly colored green, red, or pink and is found as a twisted, coated strand.

It is also used to create delays in the firing of multiple firework displays for safety.

Visco is a 3/32 - 1/8 inch (2–3 mm)-diameter cord with a black powder core.

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.