In this method of fire-making, sparks are shaved off a piece of steel by striking it briskly with a piece of flint or other rock. In actual use, the steel is struck against the flint, since it’s usually easier to do it that way. A piece of char-cloth is held against the flint (or other rock) to catch the sparks. Once a spark is caught by the char-cloth, it is easy to blow into flame. Char-cloth is made by placing pieces of woven cotton inside an airtight metal container. That container is then placed in a fire and left there until the cotton becomes charred and black. Due to the lack of air in the container the cotton doesn’t actually burn.