Why does flint make a spark

Would you get larger or more sparks with more oxygen such as a forced stream or using pure oxygen? Can you use just iron instead of steel? Keep in mind that it is the surface and the hardness of the flint and the reactivity and the hardness of the iron that are undoubtedly the main factors involved. You probably already know there are metals that react violently with oxygen. However, iron is not that reactive. And it is somewhat soft. Steel is harder, and logically more brittle. Little bits of steel can, and are, broken off by the super-fine sandpaper-like surface of the flint.

The logical mind might conceive of substituting the flint with a man-made surface. On contact with air, it oxidizes to form a layer of rust on the surface of objects.

And this layer of rust is an excellent insulator so that the iron present in the heart of the object is protected from air. But when using pyrite, a natural stone rich in iron FeS 2 , or steel, an alloy of iron and carbon, the percussion of flint causes the removal of small particles of iron which in contact with air ignite.

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If you are using charred cloth, place a piece into the depression of the tinder bundle before you begin. Hold the steel in one hand between your thumb and index finger. If you are using a pocketknife, hold the closed knife in the same fashion with the back of the knife blade facing the rock see figure 3. To generate sparks, strike the steel against the sharp edge of the rock with a quick downward motion.

Use deliberate, powerful strokes, directing the sparks toward the tinder bundle. Besides having the charred cloth in the tinder bundle, try holding a small piece under your thumb against the flint near the striking edge. Many times sparks will deflect upward away from the steel as it strikes the flint, and the cloth may catch them. Incorporating this technique can greatly increase your chances of catching a viable spark. When you see a spark fall into the tinder, immediately give a light puff of air onto the tinder bundle.

Alternatively, if you catch a good spark on the charred cloth under your thumb, quickly transfer it to the tinder bundle and blow it into flame. If the spark has begun to ignite the tinder, a small wisp of smoke will be present, and you should see a tiny glow in the bundle.

Continue to blow the tinder into flame. If the tinder does not catch, continue striking sparks. In bright and sunny conditions, place the tinder bundle in the shade or position yourself so that you cast a shadow over the tinder. That way you can see where the sparks are falling and whether the tinder is beginning to burn.

This is an excerpt from Outdoor Survival Guide. If you can create a small enough particle of fresh iron, upon contact with oxygen in the air the iron particles increased surface area will oxidize faster than it can dissipate the heat formed during the reaction. The result: the particle of iron spontaneously becomes so hot that it glows as it oxidizes — and can be used to catch tinder on fire.

Iron by itself is relatively soft and tends to bend rather than chip under the stress of a hard blow on a piece of flint. To make iron harder for use in industry, it is made into what we call steel by adding some carbon. However by making it harder, the steel is also becomes more brittle. The harder a piece of steel the smaller the pieces of iron broken from it will be when struck against a hard sharp object.

As discussed earlier, smaller pieces of iron will spontaneously burn hotter due to their increased surface area. Another way to get hotter sparks is to break off smaller pieces from the steel by striking it against a harder, sharper object.

This is why you need to keep the edges of your flint very sharp for optimum creation of hot sparks when striking the steel. Any hard stone with a sharp fracture can be utilized as long as it can break off very small pieces of steel. Flint and steel has been used in starting fires for centuries. In the days before matches were invented, flint and steel offered the ability to start a fire without having to carry a hot coal wherever one traveled, and worrying about losing it or having it go cold.

Starting a fire using flint and steel takes a more expertise and preparation than simply striking a match, however many survival experts feel this disadvantage is overcome by the fact that a wet or damp flint and steel can still be used to start a fire, and that a flint and steel can start many thousands of fires without wearing out; both very important attributes when surviving in the wilderness.