Making a fuse with black powder is a simple process and you only need a few things to get it right. You should have Water, Cotton string, and black powder. A slow burning good quality meal powder works best. To start, cut the cotton string to your desired length and dip it into the water. Take the now wet string and coat it thoroughly with the black powder. Then you simply have to let the fuse dry, an oven on a very low setting works well. Optionally, you can dissolve a small amount of potassium nitrate in your dipping water to slow down the burning of the fuse. Other popular methods are mixing flour or sugar with the black powder to make it burn even more slowly. That's all there is to it, and remember to be safe when handling flammable materials.