Marttiini Fire steel - Fire steel set. Lighting a fire with a fire steel is a great party trick and can be highly practical in outdoor situations, as well. Tip: Gently feel the striker of the new fire-starting set: you'll notice it has a kind of "thread," meaning the metal doesn't just have a 90º edge, but a small "lip" has been created with a sharpener. Use this side for striking. As you practice, this thread will wear down, and you'll notice that striking sparks becomes slightly more difficult. Fortunately, the thread is easy to renew: press the edge of the striker against something like a diamond sharpener. Conceptually, you can think of it as "pushing the metal over the edge" with the sharpener.