Black powder slurry is a paste made from black powder that is used to help light various pyrotechnic devices. It is the most common way to prime pyrotechnics. There are two commonly used forms of black powder slurry.
The first is water soluble and is usually made by adding 1 to 5% dextrin by weight to fine black powder and adding just enough water to make the mixture the consistency of thin pancake batter.
The water based mixture is commonly used for priming bulk items such as stars whereas the nitrocellulose mixture is more often used for dipping fuses. This allows the fuses to then be dipped in dry black powder, enhancing ignition greatly.