Chip Off the Old BlockFreshly broken flint, while somewhat smooth to the eye, if examined microscopically, has a rough surface. Now flint, would you believe it, is actually harder than steel. So what is the mechanism whereby one get sparks from steel and flint?
Steel and FlintWhen a piece of steel is dragged quickly across a fresh flint surface, very tiny pieces of metal are heated by the friction to a temperature above the ignition point for iron. Iron is the main component of steel. In the presence of oxygen, the steel particle burns at white heat to produce a brilliant spark and a burned out cinder!
PyrophoricDoes this not seem reasonable to you? Then consider this. Still smaller pieces of iron do not even need friction to ignite them in oxygen. Such iron is said to be pyrophoric. The video embedded below, affords visual proof that the above explanation is not only reasonable, but true as well.
- Northern Illinois University: Flint and Steel Firebuilding
- Ragweed Forge: Firemaking with Flint and Steel
- Microscopic Observations, by Robert Hooke (1780)