Replace phosphorus trisulfide with sulfur in the head of safety matches. The general heat of friction is not enough to cause a reaction in the medicine head. Only when scratching on the phosphorus layer on the side of the matchbox, the heat of friction first causes the sulfur to react with potassium chlorate, releasing more heat energy, and promoting the chemical substances in the medicine head to react and ignite.

The main components of the friction match tip are potassium chlorate and phosphorus trisulfide. Slightly rubbing on a rough surface generates enough heat to cause a chemical reaction between these two substances and ignite.